MXPA97009524A

MXPA97009524A - A dry product and a sec procedure

Info

Publication number: MXPA97009524A
Application number: MXPA/A/1997/009524A
Authority: MX
Inventors: Thomas Sikora Paul; Ludwik Grocholski Wlodzimierz
Original assignee: Dtl Sa; Ludwik Grocholski Wlodzimierz; Thomas Sikora Paul
Priority date: 1995-06-07
Filing date: 1997-12-04
Publication date: 1999-01-11

Abstract

A dried fruit or vegetable, has a water content in the range of 4% to 7%, and has a water activity of 0.4. Substantially, all cells of the dried product are not damaged. An air drying process is moderate and comprises four phases, during which the temperature of the drying air is maintained at 60 ° C. In the first phase, the relative humidity of the drying air is allowed to increase between 50% and 55%, and is maintained substantially constant at this level during the second phase by maintaining exchange of the drying air with the substantially constant fresh air. In a third stage of the process, the relative humidity of the drying medium is allowed to relatively reduce rapidly until the fourth phase begins, at such a stage, the relative humidity is allowed to approach asymptotically at a predetermined relative humidity value . During the drying process, excessive temperature differences and relative humidity differences between the temperature and the relative humidity, respectively of the drying medium and the product, are avoided in order to minimize the damage to the cellular structure of the produc

Description

A DRY PRODUCT AND A DRYING PROCEDURE FIELD OF THE I NVENTION The present invention relates to a dry product, and in particular, but not limited to, a dry biological product in which the product is dehydrated at a water content of 20% or less. The invention is also directed to a process for dehydrating a product, and in particular, although not limited to, a process for dehydrating a biological product.

BACKGROUND OF THE INVENTION There are many procedures for drying products, such as various foods, fruits, vegetables, and other biological substances. For example, WO89 / 08229 describes a system and method for drying granulated material, wherein the granulated material is subjected to a drying agent, such as nitrogen. Freeze-dried vegetables are also known. Such a method is known and known to cause cell rupture and increase the permeability of plants, to water, see US Patent Specification No. 4,788,072, column 2, lines 15 to 20. It is also known to dry slices of fruit or vegetables by dipping such slices in a sugar solution, see for example, European Patent Specification No. EP-A-0-339.1 75. When a sugar solution with an equivalent value is used with a high Dextrose content (DE), for example, a DE value of 70, the sugars of low molecular weight are able to penetrate the cells, so that there is a higher sugar content. Such dry products may not have a water activity of less than 0.4, and some of the contents of the cell, such as flavor and odor constituents, may no longer be present within the cell. When a sugar solution with a low DE content is used, for example, a DE value of 25, the sugars are extracted from the product. This dry product may also not have a water activity of less than 0.4. In addition, it is considered that due to the extraction of sugars, the flavor and odor characteristics of the product can be altered. The osmotic drying of the sugar is also considered as a pre-treatment, that is, a treatment to reduce the water content of the product, before a final drying treatment, such as frying. The water content of the osmotically dry product in this way can not be low enough to avoid spoilage, without additional measures, such as refrigeration, sterile packing or the addition of preservatives. Due to the treatment of the product in a liquid sugar solution, the sugar can completely fill the gaps or spaces between two adjacent cell membranes. It is also known to dry grapes by spraying them before harvesting them with a composition to facilitate the removal of the water from the grapes, see U.S. Patent Specification No. 5,068,988. The dried grapes retain a sufficiently high content of water in order to produce enough juice to make wine. The wines obtained using such dried grapes have a high alcohol content. It is also known to dry wood using a carefully regulated temperature and humidity regime during the drying process. The temperature and humidity regime in species and specific size is selected to ensure that the drying operation does not cause the product to sag as a result of excessive moisture and temperature gradients within the material. The drying process results in a drying time longer than that which could result from drying without moisture regulation. The details of such drying procedures are presented in a large number of normal jobs, for example, in 1991 ASHRAE Handbook, HVAC Applications. It is generally accepted in the known art that "based on heat and mass transfer analysis, the most efficient dehydration systems will maintain the maximum pressure-vapor gradient and the maximum temperature gradient between the air and the parts. interior of the product, "see I ntroduction to Food Engineering, R. P. Singh and D. R. Heldman, Academic Press (1993), at page 422. It is also generally accepted that in known drying procedures, the outer layer of the The product becomes essentially impermeable to aroma compounds, but still transmits some water vapor to allow drying to continue, see, for example, "Food Dehydration", G.V. Barbosa-Cánovas and M. R. Oaks eds. , A. I. Ch. E., Symposium Vol. 89 (1993), page 32. Finally, the PCT Application Specification No. WO 94/13146 of one of the co-inventors of the present invention describes a method and an apparatus for dehydrating biological products, wherein a closed system is used in order to ensure the retention of the essential flavor and fragrance of the natural product.

Definitions In this specification and in the claims, the following words and terms which are used herein, have the following meanings: Water content of a non-dried substance, in other words, a substance before being dried is given a percentage of the total weight of the substance not dried. Water content of a dry substance is given as a percentage of the total dry matter weight only of the dry substance, excluding all moisture. A hygroscopic substance is one in which the water content tends to balance with its surrounding parts. The water activity of a hygroscopic substance is defined as the equilibrium relative humidity of a closed and thermally insulated system, where the substance has been placed. The measurement of the same can take place with a minimum headspace and generally in accordance with the recognized procedures to measure the activity of the water. So in principle, the water activity is not different from the relative humidity of the equilibrium, except that it is expressed in terms of a scale of 0-1, instead of a scale of 0-1 00%. The activity of water measures the degree of freedom of water, retained in various forms, in a hygroscopic substance. The activity of water directly determines the physical, mechanical, chemical and microbiological properties of a hygroscopic substance, for example, interactions such as cake formation, cohesion, electrostatic charge, etc. In the food industry, water activity is a highly significant factor that must be considered for the conservation of semi-finished and finished products. In particular, the water activity threshold for deterioration mechanisms in a given hygroscopic food substance is defined as a level of water activity above significant oxidation, enzymatic binding, microbiological organic activity and other deterioration procedures that begin to occur in the damage of the organoleptic and nutritional characteristics of that substance. For example, the proliferation of microorganisms is generally considered suppressed at water activity levels below about 0.65. Other deterioration methods become progressively less active as the water activity is reduced to a value between 0.2 and 0.25, ie, at a level that corresponds approximately to the monolayer water content. Cell structure of a substance means the structure of the cells of the substance, and also means the general arrangement of the cells, so that the intracellular spaces, channels or passages, are defined between the cells, and reference is made to the damage to the Cellular structure, in general, refers to the damage caused to the cellular structure during the dehydration process, it being understood that the cells and cell structure adjacent to one side of the product can be damaged before the dehydration process, as a result of, for example , the cut of the substance or product in slices or similar. Cellular integrity of a substance refers to the degree to which the cellular structure of the substance is undisturbed or undamaged, and in particular, to the degree to which the walls of the cell remain intact to retain the organoleptic characteristics of the product. The reference to the maintenance of cellular integrity during a dehydration procedure is defined as maintaining the integrity of the cellular structure, such substance was previously dried through the drying process, so that at the end of the dehydration process, the product dry can be substantially rehydrated to its original form in substantially all aspects. The structural integrity of a substance refers to the degree to which the structure of the substance is undisturbed or damaged, including its cellular structure. The reference for maintaining the structural integrity during the drying process is defined as the maintenance of the integrity of the structure, the substance previously having been completely dried through the dehydration process, so that at the end of the dehydration process, the Dry product can be rehydrated to substantially return to its original form in substantially all aspects. In other words, in a dehydration process, which maintains the structural integrity of the substance being dried, the dehydration process is essentially reversible. For substances that have cells, maintaining structural integrity also means maintaining cell integrity, in other words, keeping cell walls substantially intact and maintaining intercellular spaces and passages. The purpose of maintaining structural integrity during a drying procedure is to help maintain the initial structural characteristics of the substance and facilitate the transfer of mass of moisture from the substances. In food and health products, for example, the initial structural characteristics include organoleptic and nutritional properties, and other typical qualities of each product in its initial form before being dried. It is assumed that only substances having a relatively high degree of structural integrity are subjected to the dehydration process according to the invention, since, otherwise, it could not be rehydrated to its original form. The degradation temperature of a substance is defined as the temperature above which the structural integrity of the substance and / or some chemical or biochemical constituents can suffer irreversible thermal damage. The organoleptic tests serve as a basis for a sensory analysis of the internal and external quality of a material. The external quality of a material is judged according to its optical and physical properties, which are perceived by the senses of vision and touch. These properties have to do with the appearance of the material, for example, color, size, shape, condition (uniformity, absence of defects and spots). Of particular importance for dry products are color (as it was before drying) and lack of soothing, fading and other discolorations. The internal quality of a material is judged according to its taste and aroma, and texture. The taste and aroma are caused by chemical properties and perceived mainly by the senses of taste and smell, which are closely intertwined. The taste is due to the sensations perceived in the tongue, while the aroma is perceived due to the stimulation of the olfactory senses with volatile organic compounds. For dry products, it is very desirable to retain the flavor and aroma characteristics of that material in its initial state. The presence of bad odors and aromas is very undesirable. The chemical compounds that form the aromatic properties of plant products need to be volatile by definition in order to be perceived at the temperature at which the product is to be used. That is to say, they must be present in a gaseous or vapor state, so that the molecules can reach the nasal passages of the people who perceive the aromas. Generally, only a small number of compounds impart the main flavor characteristics of a substance. Such volatile compounds may exist per se in the intact tissue, while others are formed enzymatically after the breakdown of the cells of the substance. It is possible to precisely measure the concentration of compounds that impart the characteristic odor of a substance using gas chromatography equipment. The texture is usually expressed as a total determination of the sensation that feed them give to the mouth. It is a combination of sensations derived from the lips, tongue, walls of the mouth, teeth and even the ears. It is desirable for dry products to maintain their textural integrity, are not too hard, too elastic or too brittle during biting, chewing and swallowing. Since the organoleptic properties of a substance are not generally equally subject to change, and are generally affected to a different degree by different stimuli, it is appropriate to examine the organoleptic properties that are most possible to be practicable in order to evaluate the degradation of the substance mostly through a better way. In food products, the amount of ascorbic acid present in the dried product is a good indicator of the degree of degradation, which the product has suffered from its initial state. This follows from the fact that ascorbic acid is particularly volatile, that is, vulnerable to elimination, especially at higher temperatures and over time (after harvesting, during storage). The losses of ascorbic acid are higher in fruits and vegetables that have a higher pH. The monolayer water content of a hygroscopic substance is defined as that amount of water that can be retained by the substance at a maximum binding energy. This water content is estimated by the fixation of a theoretical expression such as the BET equation for the absorption of moisture to the moisture absorption isotherm measured for the substance. See, for example, BET Monolayer Values in Dehydrated Foods and Food Components, H.A. Churches and J. Chirife, Lebensm-Wiss, U.-Technol, Volume 9, (1976), to pages 107-1 13.

Objects of the Invention It is an object of the invention to provide a dry product, and in particular, a dry biological product, such as, for example, a dried fruit or vegetable product, which upon rehydration possesses substantially all the properties and characteristics of the original product before of being dried, and in particular, possesses substantially all the organoleptic properties and wherein the structural integrity of the product is maintained. It is also an object of the invention to provide a dry product, the water content of which is 20% or less by weight. Furthermore, it is an object of the invention to provide a process for dehydrating a product, and in particular, a biological product such as, for example, a fruit, a vegetable or similar product, wherein the product can be dried to a water content. of 20% or less, and the structural integrity of the product before being dried, including its cellular integrity, is maintained through the dehydration process. BRIEF DESCRIPTION OF THE NONDION According to the invention, a dry product having a water content of less than 20% is provided, wherein at least 50% of the cells not adjacent to one side of the product still have a substantially undamaged membrane, and in where the water present in the product in a water activity that does not exceed 0.7. In one aspect of the invention, the water present in the dried product has a water activity not exceeding 0.65. In another aspect of the invention, the water present in the dried product has a water activity not exceeding 0.6. In general, the water present in the dry product has a water activity between 0.2 and 0.5, preferably the water activity is between 0.25 and 0.45, and ideally the water activity is between 0.3 and 0.4. In one aspect of the invention, the water content of the dried product is less than 10%, and typically, the dried product has a water content in the range of 4% to 7%. Preferably, substantially all of the cells of the dried product, which were not damaged before drying, remain substantially undamaged after drying. In one aspect of the invention, the product is a biological product, for example, a dried fruit or a dried vegetable. Typically, the dried product is in the form of a slice, and in general, the dried product is derived from a slice product, the thickness of the slices of the product before dehydration is in the range of 1 mm to 10 mm. Ideally, the thickness of the slice before dehydration is in the range of 3 mm to 7 mm. In one aspect of the invention the product contains compounds that are capable of being eluted at different temperatures, the ratio by weight of the compounds eluted at a temperature between 1 50 ° C and 200 ° C to the fraction of compounds eluted at a temperature between 40 ° C and 100 ° C is greater than 0.3. Preferably, the fraction by weight ratio of the compounds eluted at a temperature of between 50 ° C and 200 ° C to the fraction of the compounds eluted at a temperature between 40 ° C and 100 ° C is greater than 0.4. Ideally, the fraction by weight ratio of the compounds eluted at a temperature between 1 50 ° C and 200 ° C to the fraction of compounds eluted at a temperature between 40 ° C and 100 ° C is greater than 0.6. In another aspect of the invention, the product contains compounds that are capable of being eluted at different temperatures, the fraction in relation by weight of the compounds eluted at a temperature between 1 50 ° C and 200 ° C to the fraction of eluted compounds up to 200 ° C is greater than 0.25. In one aspect of the invention, the product comprises cells adjacent to one side of the product, such cells define spaces between them, at least 50% of the spaces are not completely or almost completely sugar lobes. Preferably, at least 50% of the spaces contain a gaseous medium. Ideally, at least 50% of the volume of such spaces is filled at a rate of at least 50% with the aqueous medium. In one embodiment of the present invention, the product is a banana, and the dried product has prominent gas chromatographic peaks in retention times of 6.1 and 7.3 minutes. In another embodiment of the invention, the product is a handle, and the dried product has prominent gas chromatographic peaks in retention times of 6.1 and 12.8 minutes. In a further embodiment of the invention, the product is a pineapple and the dried product has a prominent gas chromatographic peak in a retention time of 6.1 minutes. In a further embodiment of the invention, the product is a kiwi, and the dried product has a prominent gas chromatographic peak in a retention time of 6.3 minutes. In another embodiment of the invention, the product is a papaya and the dried product has a prominent gas chromatographic peak at a retention time of 6.2 minutes. In a further embodiment of the invention, the product is ginger, and the dried product has prominent gas chromatographic peaks at retention times of 6.3, 8.4 and 10.0 minutes. In addition, the invention provides an improved food preparation having as an ingredient a dry food product, wherein the dry food product has a water content of less than 20%, the dry food product is a product wherein at least 50% of the cells are not adjacent to one side of the product and still have a closed membrane, and wherein the water present in the dried food product has a water activity of less than 0.7. In one aspect of the invention, the food composition is useful as a sauce composition. In addition, the invention provides a dry product having a water content of less than 10%, wherein at least 50% of the cells not adjacent to one side of the product still have a substantially undamaged membrane, and wherein the water present in the product has a water activity less than 0.4. In one aspect of the invention, the water content of the dried product lies in the range of 4% to 7%. In another aspect of the invention, the water present in the dried product has a water activity of between 0.15 and 0.35. Preferably, the water present in the dried product has a water activity of between 0.25 and 0.3.

In another aspect of the invention, the product contains compounds that are capable of being eluted at different temperatures, the fraction by weight ratio of the compounds eluted at a temperature between 150 ° C and 200 ° C to the fraction of compounds eluted at a temperature between 40 ° C and 100 ° C is greater than 0.3. Preferably, the fraction by weight ratio of the compounds eluted at a temperature between 150 ° C and 200 ° C to the fraction of compounds eluted at a temperature between 40 ° C and 100 ° C is greater than 0.5. Advantageously, the fraction by weight ratio of the compounds eluted at a temperature between 150 ° C and 200 ° C to the fraction of compounds eluted at a temperature between 40 ° C and 100 ° C is greater than 0.6. In a further aspect of the invention, the product contains compounds that are capable of being eluted at different temperatures, the ratio by weight of the compounds eluted at a temperature between 150 ° C and 200 ° C to the fraction of eluted compounds up to 200 ° C is greater than 0.25. In another aspect of the invention, the product comprises cells adjacent to one side of the product, such cells define spaces between them, at least 50% of the spaces are not completely or almost completely filled with sugar. Preferably, at least 50% of such spaces contain a gaseous medium. Ideally, at least 50% of the volume of such spaces is filled at a rate of at least 50% with a gaseous medium. In one aspect of the invention, the product is a dried vegetable or dried fruit. The product can also be any other dry food. In one embodiment of the invention, the product comprises cells adjacent to one side of the product, such cells define between them at least 50% of such spaces containing a gaseous medium. Preferably, substantially all of the cells of the dried product, which have not been damaged prior to drying, remain substantially undamaged after drying. In addition, the invention provides a food composition having the improvement of containing a dry food product having a water content between 4% and 7%, the dried product is a product wherein at least 50% of the cells do not Adjacent to one side of the product still has a closed membrane, and the water present in the dried product has a water activity of less than 0.4. In one aspect of the invention, the food composition is useful as a sauce composition.

The dry product according to the invention has many advantages. It has a sufficiently low water activity, to ensure a long-term resistance to degradation at typical storage temperatures of approximately 20 ° C to 30 ° C. A water activity in the range of 0.3 to 0.4 ensures a long-term resistance to degradation at such storage temperatures during a relatively long storage period. Depending on the product at water activity levels of up to 0.7, certain products are resistant to degradation and deterioration at typical storage temperatures of approximately 20 ° C to 30 ° C during relatively long storage periods. In the case of fruits and vegetables, the product has improved organoleptic properties with respect to dried products by other known methods. This is believed to be due at least in part to the maintenance of structural integrity, and in particular to the cellular integrity of the product. In general, it has been found that when the cellular integrity of at least 50% of the cells of the product is maintained, and in particular, 50% of the inner cells the dried product can be rehydrated, to obtain substantially all the properties and characteristics that the product has before dehydration. Needless to say, when the cellular integrity of substantially all cells is maintained, the properties and characteristics of the rehydrated product are even closer to those properties and characteristics of the product before being dehydrated. When the integrity has been maintained through the dehydration procedure, the properties and characteristics of the rehydrated product still remain very close to those properties and characteristics of the product before being dehydrated. In addition, the invention provides a method for dehydrating a product by pushing a gaseous drying medium to contact the product in a chamber, wherein the relative temperature and humidity of the drying medium are controlled so that the rate of removal of the product from the drying medium is controlled. The water in the product is such that damage to cell integrity of the product during the drying process is minimized. Preferably, the temperature and relative humidity of the drying medium are controlled so that the cellular integrity of at least 50% of the product cells not adjacent to one side of the product is maintained during the drying process, ideally The cell integrity of the entire product is maintained during the drying process.

In one aspect of the invention, the rate of water removal from the product is such that it minimizes damage to the structural integrity of the product during the drying process. Preferably, the structural integrity of at least 50% of the product cells not adjacent to one side of the product is maintained during the drying process. Advantageously, the structural integrity of the product is substantially maintained during the drying process. The dehydration process according to the invention establishes a moderate drying regime, which maintains optimum conditions for the transfer of moisture mass of the product being dried, while substantially maintaining the structural integrity of the entire product during the process of drying. By closely controlling the temperature and relative humidity of the drying medium, the surface of the product being dried remains permeable to water, moisture and water vapor moving from the interior of the product to the drying medium. The improved mass transfer of the product as a result of the moderate drying process of the invention results in a superior product, as well as an efficient drying process, due to the reduction in energy consumption. The drying regime avoids subjecting the product and the material being dried to thermal and pressure stresses, thus maintaining the structural and cellular integrity of the entire product during the drying process, while maintaining optimum conditions for transfer of heat and mass. In one embodiment of the invention, the relative humidity of the drying medium is controlled so that the difference between the relative humidity of the drying medium and the equilibrium relative humidity of the product does not exceed 70% relative humidity. Preferably, the relative humidity of the drying medium is controlled so that the difference between the relative humidity of the drying medium and the relative humidity of the product equilibrium does not exceed 60% relative humidity. Advantageously, the relative humidity of the drying medium is controlled so that the difference between the relative humidity and the drying medium and the equilibrium relative humidity of the product does not exceed 50% relative humidity. In another aspect of the invention, the relative humidity of the drying medium in the chamber is allowed to increase to a maximum value, the lime lies within the range of 30% to 70%. Preferably, the maximum value of the relative humidity of the drying medium in the chamber is in the range 50% to 70%. Advantageously, the maximum value of the relative humidity of the drying medium in the chamber is in the range of 50% to 55%. In another embodiment of the invention, at the relative humidity value of the drying medium reaching the maximum value, the relative humidity of the drying medium in the chamber is kept substantially constant at the maximum value, or allows it to be reduced only gradually maintaining the relative humidity of the drying medium that is being supplied to the chamber, substantially constant, until the relative humidity of the drying medium in the chamber begins to fall or begins to fall in a rate of increase. Preferably, the relative humidity of the drying medium in the chamber is allowed to fall relatively quickly after the drop in the relative humidity of the drying medium that has started or the rate of fall of the relative humidity of the drying medium that has started. to be increased, until the water content of the product approaches the desired water content, and the evaporation rate of the product water becomes substantially independent of the drying medium. In one aspect of the invention, the evaporation rate of the product water becomes substantially independent of the drying medium, the relative humidity of the drying medium is controlled to asymptotically approach a predetermined value of the relative unit that provides the desired product to the desired water content. In another aspect of the invention, the predetermined value of relative humidity is lower than the relative humidity of the equilibrium of the product, which corresponds to the desired water content, and the difference between the predetermined relative humidity of the drying medium and the equilibrium relative humidity of the product corresponding to the content of desired water is in the range of 20% to 40% relative humidity. In general, the difference between the predetermined relative humidity value and the equilibrium relative humidity of the product corresponding to the desired water content is in the range of 25% to 35% relative humidity, and in many cases, the difference between the The default value of relative humidity and the relative humidity of the product equilibrium corresponding to the desired water content is approximately 30% relative humidity. Depending on the product, the relative humidity of the drying medium can be maintained substantially at the predetermined relative humidity value during a period in the range of 30 minutes to 120 minutes. In another embodiment of the invention, the drying medium is calculated through the chamber, so that the speed of the drying medium in relation to the product lies in the range of 1 M per second to 3 M per second. Preferably, the drying medium is circulated through the chamber, so that the speed of the drying medium relative to the product is in the range of 1.5 M per second to 2.5 M per second. Advantageously, the drying medium is circulated through the chamber, so that the speed of the drying medium relative to the product lies on the scale of approximately 2 M per second. In general, it is preferred that during the period while the relative humidity of the drying medium in the chamber is being maintained constantly or only gradually in reduction, the relative humidity of the drying medium in the chamber is not more than 50% humidity relative to the relative humidity of the product, to minimize the damage to the cellular and structural integrity of the product. Preferably, during the period while the relative humidity of the drying medium in the chamber is being maintained substantially constant or only gradually decreases, the relative humidity of the drying medium in the chamber is not more than 40% relative humidity less than the relative humidity of the equilibrium of the product, and preferably is not more than 30% relative humidity less than the relative humidity of the product. In another embodiment of the invention, during the period while the relative humidity of the drying medium in the chamber is falling relatively fast, the relative humidity of the drying medium is controlled, so that the relative humidity of the drying medium in the chamber does not it is greater than 70% relative humidity, lower than the equilibrium relative humidity of the product, to minimize the damage to the cellular and structural integrity of the product. Preferably, during the period while the relative humidity of the drying medium in the chamber drops rapidly and relatively, the relative humidity of the drying medium is controlled so that the relative humidity of the drying medium in the chamber is not more than 60% of relative humidity less than the relative humidity of the product, and advantageously, it is not more than 50% relative humidity less than the relative humidity of the product. Ideally, the drying medium is recirculated and preferably, the relative humidity of the drying medium in the chamber is controlled through the introduction of the fresh drying medium into the recirculation drying medium, and the rate at which the medium fresh drying is introduced does not exceed 21% by weight of the mass flow rate of the drying medium. In one embodiment of the invention, the rate at which the fresh drying medium is introduced does not exceed 15% by weight of the mass flow rate of the drying medium. In another embodiment of the invention, the rate at which the fresh drying medium is introduced does not exceed 10% by weight of the mass flow rate of the drying medium. In a further modality of the invention, the rate at which the fresh drying medium is introduced does not exceed 7% by weight of the mass flow rate of the drying medium. In a further embodiment of the invention, the rate at which the fresh drying medium is introduced does not exceed 4% by weight of the mass flow rate of the drying medium. In another embodiment of the invention, the fresh drying medium is introduced at a substantially constant rate not greater than 7% by weight of the mass flow rate of the drying medium during the period while the relative humidity of the drying medium in the the chamber is being maintained substantially constant at the maximum relative humidity value. In another embodiment of the invention, the fresh drying medium is introduced at a substantially constant rate of no more than 5% by weight of the mass flow rate of the drying medium during the period, while the relative humidity of the drying medium. in the chamber, the maximum relative humidity value is maintained substantially constant. In a further embodiment of the invention, a fresh drying medium is introduced at a substantially constant rate of not more than 4% by weight of the mass flow rate of the drying medium during the period while the relative humidity of the drying medium in the the chamber is being maintained substantially constant at the maximum relative humidity value. In yet another embodiment of the invention, a fresh drying medium is introduced at a substantially constant rate of not more than 3% by weight of the mass flow rate of the drying medium during the period while the relative humidity of the drying medium in the the chamber is being maintained substantially constant at the maximum relative humidity value. In another embodiment of the invention, a fresh drying medium is introduced at a substantially constant rate of no more than 2% by weight of the mass flow rate of the drying medium during the period while the relative humidity of the drying medium in the The chamber is being maintained substantially constant at the maximum value of relative humidity. In a further embodiment of the invention, a fresh drying medium is introduced at a substantially constant rate of not more than 1% by weight of the mass flow rate of the drying medium during the period while the relative humidity of the drying medium in the the chamber is being maintained substantially constant at the maximum value of the relative humidity. In another embodiment of the invention, during the period while the relative humidity of the drying medium in the chamber is relatively rapidly falling, a fresh drying medium is introduced at a rate of no more than 21% by weight of the flow rate in mass of the drying medium. In general, the fresh drying medium is introduced and increases from the beginning of the period until the end of the period during which the relative humidity of the drying medium in the chamber is falling relatively rapidly. In practice, no fresh drying medium is introduced into the recirculation drying medium until the relative humidity of the drying medium has reached its maximum value. In another embodiment of the invention during the period while the relative humidity of the drying medium in the chamber is approaching asymptotically at the predetermined value of the relative humidity, a fresh drying medium is introduced at a rate no greater than 5% by weight of the Mass flow regime of the drying medium. In a further embodiment of the invention, a fresh drying medium is introduced through an inlet opening and an outlet drying means exits through an outlet opening, the size of the inlet and outlet openings have been controlled as a function of the nominal exposed surface area of the product according to the modulation index (Ml) which is defined as: Ml = Kp x NSP (Sen + Se?) / (Sen * Sex) where Sen is the transverse area of the inlet opening to make the drying medium cool, Sex is the cross-sectional area of the outlet opening to expel the drying medium, and NSP is the nominal exposed surface area of the product, and Kp is a constant whose value depends on the product to be dried and the pressure characteristics / flow of the drying medium, and during the period while the relative humidity of the drying medium of the chamber is being maintained substantially constant at the maximum value, the value of the modulation index, lies on the scale of 1, 000 to 10, 000 . Preferably, during the period while the relative humidity of the drying medium in the chamber is being maintained substantially constant at the maximum value, the value of the modulation index lies on the scale of 2,000 to 8,000. Preferably, the temperature of the drying value is controlled, not to increase to, or above a degradation temperature, which could cause irreversible thermal damage to the product. In general, the temperature of the drying medium does not exceed 70 ° C. Typically, the drying medium is maintained at a temperature within the range of 40 ° C to 70 ° C, in general, the drying medium is maintained at a temperature within the range of 55 ° C to 65 ° C. In one embodiment of the invention to reach its maximum value, the temperature of the drying medium remains substantially constant thereafter.

The drying medium can be any suitable medium, however, a typical drying medium is air, or for example, the drying medium can be nitrogen, and in some cases, the drying medium can be air enriched with nitrogen. By recirculating the drying medium, the process according to the invention obtains a relatively high degree of energy efficiency. However, the energy efficiency of the process according to the invention also results from the improved water removal regime of the product, which is made possible by virtue of the fact that the channels and passages adjacent to the faces of the product remain undamaged. during the drying process, in this way, facilitating the elimination of efficient water from inside the product. Accordingly, proper control of the temperature and relative humidity of the drying medium results not only in a superior product quality, but also in a reduced drying time and energy requirements. Controlling the temperature and relative humidity of the drying medium in the chamber to provide a sufficiently high water vapor density in the chamber effectively regulates the rate at which water is released from the product by limiting the numerous gradients in temperature and moisture that occurs in the removal of moisture from a hygroscopic substance. The proper regulation of these ingredients serves to maintain the structural integrity and in the case of biological material with the cellular structure prevents the formation of an impermeable surface layer, which has an adverse effect both on the dry product and also on the elimination of the water from inside the product during the last stages of the drying process. Furthermore, the invention provides a process for preparing a dry product having the following characteristics: a water content of between 2% and 20%, preferably between 2% and 10% and advantageously lower than the level corresponding to the threshold of water activity where deterioration of the dry product begins, but less than the lower limit of the water content for the monolayer, substantially all cells are not adjacent to an exposed face of the product until they have a relatively high degree of structural integrity as it is demonstrated through a substantially undamaged cell membrane, and the product has a water activity of less than 0.7, preferably a water activity of less than 0.4, and ideally of 0.3 and 0.4, more preferably at a value that reduces minimize the effects of deterioration mechanisms. In general, the cells of the product are not divided by the drying process according to the invention. In particular, the cell membranes of the product, in general, are not damaged. As a result of this, many organoleptic compounds and nutritional elements located in, or within the membranes of the cells are retained. It seems that even much of the product of the invention has a membrane, which is in such a state that the organoleptic compounds are more noticeable than in the fresh state, that is, they can be more easily released in the mouth. The dry product of the invention retains many of the organoleptic compounds of the product as they were before drying, including those comprising an aroma and flavor, and advantageously contains a portion of substantially the flavoring compounds in the lower boiling fractions, typically below 40 ° C, contained in the product as they were before drying. According to one embodiment of the product of the invention, the product containing compounds that are capable of being eluted at different temperatures, the weight ratio fraction of the compounds eluted at a temperature between 150 ° C and 200 ° C at fraction of compounds eluted at a temperature of between 40 and 100 ° C is greater than 0.3, preferably greater than 0.5, for example, between 0.6 and 2. The fraction of the weight ratio of the compounds eluted at a temperature of between 150 ° C and 200 ° C to the fraction of the compounds eluted up to 200 ° C is greater than 0.25, preferably greater than 0.3, for example, 0.35-0.4. Advantageously, a substantial proportion of the spaces or channels between the cells adjacent to one side of the product are not filled with sugar and remain open. Preferably, a substantial proportion of the spaces or channels contains a gaseous medium, such as air, N, mixtures of N2 + O2, air enriched with oxygen, water vapor, or others. The moderate nature of the drying process of this invention minimizes the degradation of the cell wall whereby the constituents of both sugars and flavor remain inside the cells, instead of residing in the spaces between the cells. The dry product of the invention can be a fruit, a fruit or vegetable food product, such as pineapple, banana, papaya, mango, other tropical fruits, melon, carrots, cabbages, celery, pepper, spinach, beans, plums, apples , pears, mushrooms, grapes, oranges, lemons, limes and other fruits and vegetables, but can also be herbs, spices, tobacco, blood, sperm, bacteria, meat, marine food, tea leaves, seaweed, algae, grains of coffee, cocoa beans, nuts, eggs and other food and biological products. The invention also relates to a process for dehydrating other products and substances, for example, products that do not contain cells, such as chemical compounds, pharmaceutical compounds or preparations, as well as non-biological products and substances. In an alternative process according to the invention, a gaseous drying medium is heated and pushed to contact the product to be dried, the temperature of the drying medium which is in contact with the product to be dehydrated is lower than the degradation temperature of the product, the temperature of the product to be dehydrated is increased in an uncontrolled manner during the drying process, the process comprises at least one step wherein the temperature of the drying medium is increased from a first temperature to a temperature, which may be adjacent to the maximum dehydration temperature, but lower than the degradation temperature. In one aspect of the invention, the increase in temperature to the drying medium is such that during such a step, there is a temperature difference between the product and the drying medium, such difference being between 0.1 ° C and 5 ° C, but it may be less than 2.5 ° C, it may be less than 1.5 ° C. In another aspect of the invention, the temperature of the drying medium can be increased at a rate of less than 5 ° C / hour. Prior to this step, the product may be subjected to another treatment, such as a treatment that does not damage the cells of a product prepared according to the invention. For example, the drying medium can first be maintained at a temperature of about 40 ° C until the temperature reaches about 40 ° C within the product, while the drying product can then be heated at such a rate that the temperature difference between the product and the drying medium is less than about 5 ° C, preferably less than 2.5 ° C. In general, a stable and continuous increase in the temperature of the drying medium minimizes the damage to the membranes of the cell, so that a high percentage of them remain intact while the humidity inside the cells migrates through the cells. of them and is eliminated by the drying medium. The moderate drying regime, wherein the controlled temperature difference between the drying medium and the product is maintained as mentioned above, results in a process wherein the constituents of color and flavor are not removed, but rather the Water is eliminated from the cells. According to an alternative embodiment of the process according to the invention, when the water content of the product to be dehydrated is less than 10%, the drying medium is heated to such a regime that the temperature difference between the product and the drying medium is less than about 2.5 ° C. In this case, the product is pre-dried at a temperature of 40 ° C to 50 ° C until the product reaches a water content of less than 20%, preferably less than 10%. In an alternative embodiment of the invention, the rate of increase in temperature of the drying medium is such that the temperature of the drying medium reaches the maximum dehydration temperature at about the same time as the desired water content of the product is retained.

In another alternative embodiment of the invention, the rate of increase of the temperature of the drying medium is substantially constant. Ideally, the maximum dehydration temperature is lower than the degradation temperature of the product. In general, the maximum dehydration temperature does not exceed 70 ° C. Typically, the maximum dehydration temperature lies in the range of 40 ° C to 50 ° C. In one aspect of the invention, the product is dried at a water content of less than 20%. In another aspect of the invention, the product is dried at a water content of about 10%. Preferably, the drying medium is recirculated. Preferably, during the end of the dehydration process, less than 4% by volume of the fresh drying medium is added to the drying medium. Advantageously, at the end of the dehydration process, no more than 1% of the moisture of the recirculated drying medium is condensed from the drying medium as it is being recirculated. In another embodiment of the invention, the product is dried at a water content below about %, and the relative humidity of the drying medium during the period while the water content of the product is being reduced below 20%, lies in the range of 10% and 20%. In a further embodiment of the invention, the product is dried at a water content of less than 7%. In addition, the invention provides a dried product according to the process according to the invention.

BRIEF D ESCRI PTION OF THE B UJOS The invention will be more clearly understood from the following descriptions of some non-limiting examples and modalities thereof, which are given by way of example only with reference to the accompanying drawings, in which: Figure 1 is a schematic view of an apparatus suitable for performing a dehydration process according to the invention, Figures 2 to 5 are enlarged views of portions that are close to the shell and parts inside of apple slices before drying and after drying, respectively using the procedure according to the invention and known methods, Figure 6 shows graphs of the relative humidity and temperature of the drying medium, and the equilibrium relative humidity of the product against time during an example of the dehydration process according to the invention, Figure 7 shows graphs of the relative humidity and the temperature of the medium of sec. the time for another example of the dehydration process also according to the invention and Figures 8 to 60 show gas chromatographic fingerprints of products before being dried and after being dried using the dehydration method according to the invention, and also show gas chromatography fingerprints of all, but one of the products after having been rehydrated subsequent to being dried using the dehydration process according to the invention and other dehydration procedures.

DETAILED DESCRIPTION OF THE INVENTION Before describing the examples of the dehydration process according to the invention, a drying apparatus which is suitable for carrying out the dehydration process will first be described with reference to Figure 1. Of course, it will be appreciated that the process of Dehydration is not limited to being performed in the apparatus of Figure 1, and many other different types of apparatus can be used. The drying apparatus of Figure 1 comprises an enclosed insulated drying chamber 1, having an access opening 2, which is closed through a door 3 for adapting trays 4, on which the products will be dehydrated. that will be placed in camera 1. An inlet opening 5 is provided to chamber 1 for introducing the gaseous drying medium into chamber 1, and an exit opening 6 provides the imination of the drying medium from chamber 1. A duct 7 extends from the outlet 6 to the inlet 5 for the recirculation of the drying medium back to chamber 1. A fan 8 in the duct 7 circulates the drying medium through the duct 7 in the direction of the arrow A and in turn through the drying chamber 1 also in the direction of the arrow A. A heater 9 located in the duct 7 between the fan 8 the inlet 5 heats the drying medium as it is being returned to the drying chamber 1. A capacitor 10, which can be operated to condense part of the water outside the drying medium, is located in the duct 7 between the fan 8 and the heater 9. An inlet valve 1 1 to introduce a fresh drying medium to the duct 7 is located upstream of the fan 8. The inlet valve 1 1 can communicate directly with the ambient air to introduce fresh air into the duct 7, or alternatively can introduce a fresh drying medium from a source of drying medium 1 2, e.g., nitrogen contained in a gas bottle or other suitable container. An outlet valve 14 for ejecting part of the recirculated drying medium from the duct 7 is located between the condenser 10 and the heater 9. Control means, mainly, a central programmable logic controller 15, which is a computer that controls the controls of the apparatus in response to signals received from sensors, which are described below and which are located at appropriate places in the apparatus. A control link 16 activates and deactivates the fan 8 under the control of the central controller 1 5. The inlet valve 11 and the outlet valve 14 are controlled through the central controller 15 through control links 1 7 and 18, respectively. The control links 19 and 20 control the heater 9 and the condenser 10, respectively. A temperature sensor 22 located at the inlet 5 towards the drying chamber 1 verifies the temperature of the drying medium that is being introduced into the drying chamber 1. The signals of the temperature sensor 22 are transmitted to the controller 15 through a link 23. A humidity sensor 25 is located in the drying chamber 1, and in this case is provided through a psychometric device to verify the relative humidity of the drying medium in the drying chamber 1. The humidity sensor 25 is located in the drying chamber 1 away from the outlet 6, but towards the outlet 6. A link 26 transmits the signals of the humidity sensor 25 to the controller 1 5. A humidity sensor 27 is located in the duct 7 downstream, but adjacent to the condenser 10 to check the relative humidity of the drying medium as it leaves the condenser 10. The humidity sensor 27 is also provided through a psychometric device. A link 28 transmits the signals from the humidity sensor 27 to the controller 15. A product water loss sensor 30, which is provided by a load cell device, is located in the drying chamber 1 to verify the total weight of the product being dried to determine the actual water content of the product as the dehydration process proceeds. In the examples described below the water loss sensor 30 was not used, rather it will be discussed below, the equilibrium relative humidity of the product was verified, since the water content is a function of the equilibrium relative humidity. The product water loss sensor 30 is located in the drying chamber 1 so that the trays 4 with the product thereon are supported on the water product loss sensor 30. A link 31 transmits signals from the sensor of product water loss 30 towards the controller 15. During the dehydration process, the weight of the product in the trays 4 changes, so that the water loss of the product can be valued. As the dry matter content of the product can be assessed by heating a sample of the product to a temperature of about 1 00 ° C in a laboratory test for a specified time in a recognized test procedure, the water content of the product can be determined from the weight of the product, which is verified through the water loss sensor 30 as the drying procedure proceeds. Accordingly, in response to the signals received from the temperature sensor 22, the humidity sensors 25 and 27 and the product water loss sensor 30, the controller 1 5 controls the operation of the fan 8, the heater 9 in the inlet and outlet valves 11 and 14, respectively. If it is desired to operate the capacitor 10, the capacitor 10 can also be controlled through the controller 15 in response to the signals received from these sensors. To control the inlet and outlet valves 11 and 14, respectively, the cross-sectional area of the opening presented to the fresh drying medium and to the outlet drying medium is controlled. The cross-sectional area of the opening presented to the medium at right angles to the flow of the medium. The cross-sectional area of the opening defined by the inlet valve 11 hereinafter is represented by Se, and the cross-sectional area of the opening defined by the outlet valve 14 is hereinafter represented by Se x. In certain cases, the inlet and outlet valves 11 and 14, respectively, may remain closed during all or part of the process. The combination of the pressure drop across the fan 8 together with tiny holes and cracks, which in general could occur naturally in the duct 7 and in the drying chamber 1 1, can provide a sufficient exchange of the drying medium, mainly the drying air with fresh air for an efficient operation of the dehydration process in the inlet and outlet valves 11 and 14, respectively. The significant ability of air to carry water vapor at elevated temperatures also represents the ability to operate the apparatus to carry out a dehydration process according to the invention with little or no added fresh air, and very little moisture ingress. carried in the drying air of the appliance. Examples of the dehydration process according to the invention for drying fruit and vegetable products will now be described using the apparatus of Figure 1. However, it will be readily apparent to those skilled in the art that the dehydration procedures can be carried out in any other suitable apparatus. In the examples of the dehydration process, unless otherwise specified, the drying medium is air. The dehydration processes can be performed at pressures less than, or greater than atmospheric pressure, however, it is preferred that the dehydration processes be performed at a substantially atmospheric pressure, or at a pressure just above atmospheric pressure, for example , up to 1.2 x 1? 5 Pa. In the examples of the dehydration processes described herein, the pressure of the drying medium in the drying chamber 1 is maintained slightly above atmospheric pressure. In a preferred dehydration process according to the invention, the process proceeds sequentially through four phases, namely, Phase 1 - an increasing temperature phase, Phase 2 - a high humidity phase, Phase 3 - a moisture phase of decline, and Phase 4 - an asymptotic phase. There is no sharp cutoff between the respective phases, rather the phases emerge gradually from one phase to the next. To facilitate the understanding of this dehydration method according to the invention, the four phases will now be described under separate headings, and with reference to Figure 6. Figure 6 illustrates the parameters, mainly, temperature and relative humidity, of the medium dried, which were verified during a dehydration process according to the invention, wherein I DARED apples were dehydrated. Figure 6 also illustrates the equilibrium relative humidity of the apples during the dehydration process. Graph A is a graph of the temperature and the drying medium against time. The Graph B is a representation of the relative humidity of the drying medium against time. Figure D is a representation of the equilibrium relative humidity of apples against time. Graph A was designed from the signals received from the temperature sensor 22 in the drying chamber 1. The relative humidity of the drying medium illustrated in Figure D was obtained from the humidity sensor 25 in the drying chamber. The equilibrium relative humidity of the apples illustrated in Figure D was determined at half-hour intervals during the drying process. In each half hour interval, a sample of the apples was eliminated and its equilibrium relative humidity was determined. The I DARED apples were sliced into slices with a thickness of about 3 mm and were loaded into the drying chamber 1 on the two trays 4 as illustrated in Figure 1.

Phase 1 - Increasing temperature phase In Phase 1, the drying medium is circulated through the fan 8, and the exchange of the drying medium with the surrounding atmosphere is minimized. In other words, the inlet and outlet valves 1 1 and 14 are closed, and only the exchange of the drying medium with the surrounding atmosphere occurs through the cracks, and imperfections in the duct seal and the drying chamber 1 . Heat is applied to the drying medium to increase the temperature of the drying medium to a first fixing point, which, although low, is relatively close to the maximum dehydration temperature at which the dehydration process is carried out. . The maximum dehydration temperature should never be exceeded, and preferably, it should be less than the degradation temperature of the product being dried. Phase 1 essentially begins when the product to be dried has been placed in the drying chamber 1 and the door 3 has been closed. The temperature difference between the drying medium and the product should not result in damage to the structural integrity of the product as a result of excessive thermal stress. Typically, the product is introduced to the drying chamber 1, when the temperature of the drying medium is approximately 40 ° C. Phase 1 continues until the temperature of the drying medium reaches the first fixing point, and the relative humidity of the drying medium reaches a first fixing point, which will be the maximum value of the relative humidity to which it can be allowed the increase of the drying medium. The first points of fixation of the temperature and relative humidity of the drying medium depend on the product that is drying. The temperature of the first fixing point can vary from 50 ° C to 70 ° C, and the first fixing point of the relative humidity of the drying medium can vary from 30% to 70%. In the example illustrated in Figure 6, the first temperature fixing point which is indicated by the letter E, is approximately 60 ° C, and the first relative humidity fixing point which is indicated by the letter F, it is approximately 55%. In this way, in the temperature of the drying humidity and the relative humidity of the drying medium that reaches up to 60 ° C, and 55% respectively, the first phase ends, and the process goes to the second phase, which will be described below. During the first phase, when the temperature of the drying medium reaches the first fixing point, the heater 9 is controlled to maintain the temperature of the drying medium substantially at the first fixing point. In addition, during the first phase, the relative humidity of the drying medium can fluctuate, however, it is not allowed to exceed the first fixing point, and if necessary, this can be achieved by providing a sufficient exchange of the drying medium with the atmosphere through the inlet and outlet valves 11 and 14, respectively. In the temperature and relative humidity of the drying medium in the drying chamber 1 reaching the first respective fixing points, the heater 9 and the inlet and outlet valves 11 and 14 are adjusted to maintain the temperature and relative humidity of the means of drying substantially at the first fixing points as the process goes to the second stage. The value of the equilibrium relative humidity of the product at the end of the first phase is indicated by the letter C in Graph D of Figure 6, which is approximately 93%. As discussed above, the pressure of the drying medium in the drying chamber 1 is maintained at a pressure slightly above atmospheric pressure, and there must be any tendency towards an overpressure development of the drying medium in the drying chamber 1. and a correction is made through the use of a pressure release valve (not shown). The first phase of the drying procedure of the example illustrated in Figure 6 takes approximately 30 minutes.

Phase 2 - High humidity phase During the second phase, in general, the flow rate of the drying medium is kept constant and similar to the flow rate during the first phase, so that the speed of the drying medium on the surface The exposed product is maintained at a speed similar to that during the first phase. The temperature and relative humidity of the drying medium remains substantially constant at the first respective fixing points. This is achieved by maintaining the fixing of the heater 9 and the inlet and outlet valves 11 and 14, respectively, in their respective fixings to which they were fixed at the end of the first phase. The second phase is completed when there is insufficient moisture available in the product to maintain the relative humidity of the drying medium substantially constant without altering the flow rate of the drying medium or the exchange rate of the drying medium with the atmosphere. At the end of the second phase it is determined how the point in the procedure where the relative humidity of the drying medium begins to reduce rapidly, or if the relative humidity of the drying medium has begun to decrease, in order to the second phase is the point at which the speed at which the relative humidity of the drying medium is decreasing begins to increase significantly. In Graph B of Figure 6, the end of the second phase is indicated by point G. In this stage, the second phase is completed. In general, the product that is drying will contain an amount of free water, and at the end of the second phase, in general, it is determined when this free water has run out. In general, it is at that stage that the rate of evaporation of the product water falls below the rate of vapor removal, which has been substantially maintained during the second phase. The value of the equilibrium relative humidity of the product at the end of the second phase is indicated by point K in Graph D of Figure 6. During the second phase, the relative humidity of the drying medium may remain not completely constant. However, as seen in Figure 6, the relative humidity during the second phase remains substantially constant for the initial part of the second phase and gradually begins to decrease during the latter part of the second phase. However, in such cases, as discussed above, the end of the second phase is determined when the rate of reduction of the relative humidity of the drying medium begins to increase significantly. If desired, a number of fixing points, both temperature and relative humidity can be set during the second phase, and when there is insufficient moisture available in the product to maintain the relative humidity of the drying medium at the end of the points of fixation, is determined as being the end point of the second phase. As discussed above, the relative humidity of the drying medium is maintained substantially constant at about the maximum level of relative humidity during the second phase, mainly, the high humidity phase. This is achieved by fixing the inlet and outlet valves 11 and 14 to control the exchange of the drying medium with the atmosphere at the end of the first phase. It has been found that there is a relationship between the area through which the drying medium is exchanged with the atmosphere at the nominal exposed surface area of the product, which is exposed to the drying medium in the drying chamber to maintain humidity relative substantially constant during the second phase. This relationship can be expressed in terms of modulation index Ml. The modulation index is equal to a constant multiplied by the nominal surface area of the product divided by the area S. In this case, assuming there are no spills in the duct 7 and the drying chamber 1, the area S through which the drying medium is exchanged with the atmosphere is equal to (Sen x Sex) / (Sen + Sex). The modulation index can then be expressed by the following formula: Ml = Kp x NSP / S = K x NSP (Sen + Sex) / Sen x Sex where Kp is a constant whose value depends on the particular type of product that is being drying and the pressure / flow characteristics of the drying medium, and of the fan 8, NSP is the nominal surface area of the product exposed to the drying medium. The value of the modulation index during the second phase of the dehydration process preferably remains within the range of 1, 000 <.; M l < 10,000 and more preferably remains within the range of 2,000 < Ml < 8,000 The purpose of establishing control in the evaporation regime is to achieve the elimination as quickly as possible of the water consistent with a structural integrity of maintenance, and to achieve an optimal retention of the initial structural properties of the product that is drying. Instead of, or also to control the relative humidity of the drying medium that is being returned to the drying chamber 1, by controlling the exchange of the drying medium with fresh drying medium, the relative humidity of the drying medium can be controlled by the capacitor 10. In the example of Figure 6, the second phase takes approximately seventy-five minutes.

Phase 3 - declining moisture phase The third phase of the dehydration process begins at the end of the second phase, in other words, when the speed at which the relative humidity of the drying medium within the drying chamber begins to decrease significantly , while both the temperature of the drying medium in the drying chamber and the exchange rate of the drying medium are kept substantially constant. In the third stage, the relative humidity of the drying medium in the drying chamber is allowed to continue reducing. However, the speed at which the relative humidity is allowed to be reduced is controlled so that the rate of evaporation of the water in the product does not exceed a rate of evaporation, which could result in damage to the structural integrity of the product. . The speed at which the relative humidity of the drying medium is allowed to reduce during the third phase is controlled by regulating the exchange of the drying medium with the atmosphere through the inlet and outlet valves 11 and 14, respectively. Concurrently, in some cases, the temperature of the drying medium may be varied during the third phase, provided that it does not exceed the degradation temperature of the product being dried.

During the third phase, the moisture evaporation regime of the product is preferably modulated in order to maintain the gradients in temperature and relative humidity between the drying medium and the product within the limits that will maximize the humidity evaporation rate of the product, while at the same time avoiding damage to the structural integrity of the product. These limits vary from species to species, and also vary depending on the method of preparation of the product to be dried, and the final desired characteristics of the dried product. However, the limits can be identified for each series. In general, the rate of introduction of the fresh drying medium to the recirculation drying medium increases as the third phase progresses. It is important that the temperature of the drying medium should be closely verified during the third phase, since the evaporative cooling effect is reduced as the dehydration process continues. In order to prevent the undesired temperature from increasing during the third phase, the heat provided to the drying medium, in general, is reduced, and the rate of circulation of the drying medium can be reduced.

The third phase continues until the evaporation rate of the product water is virtually reduced without considering the exchange drying rate of the drying medium with the fresh drying medium. In the example of Figure 6, the end of the third phase is identified by the point H in the graph B of relative humidity. Point I in Graph D indicates the equilibrium relative humidity of the product at the end of the third phase. The third phase of the example of Figure 6 takes approximately one and a half hours.

Phase 4 - Asymptotic phase The fourth phase begins at the end of the third phase. During the fourth phase, the relative humidity of the drying medium is allowed to approach asymptotically at a predetermined value, which is below the equilibrium relative humidity of the product, which corresponds to the desired final water content of the product. Typically, the difference between the value of the predetermined relative humidity of the drying medium and the final equilibrium relative humidity of the product at the process temperature is of the order of 30% relative humidity, although this value will vary from product to product, and It will also vary depending on the final water content at which the product will be dried. The equilibrium relative humidity of the product during the fourth phase is dictated enormously by the temperature of the drying medium inside the drying chamber, and the water content of the monolayer of the product, and is largely independent of the exchange regime of the drying medium with the atmosphere. The end of the fourth phase occurs when the equilibrium relative humidity of the product reaches the equilibrium relative humidity that corresponds to the desired final value of the water content of the product, provided that the value of the water content of the product is uniform throughout. the product. The fourth phase of the example of Figure 6, takes approximately one hour and three quarters of an hour. There is a minimum water content, which can be obtained for products during the fourth phase, the level of this depends on factors that include the water content of the monolayer of the product that is drying, the relative humidity of the drying medium that enters the drying chamber 1, and the temperature of the drying medium inside the drying chamber 1. Although the method of the invention may produce a lower moisture removal rate of the product in the initial portion of the dehydration cycle, the total drying time to reach a final moisture content set is in most cases significantly shorter for Conventional forced flow hot air drying procedures. It has been found that the drying process of the invention can be completed in a period that can be as short as tenths of the time it takes to dry the product by freeze drying procedures. The dehydration processes according to the invention, by means of which the process comprises the previous phases, which have been carried out using the apparatus of Figure 1. In all cases, two trays 4 were introduced carrying respective loads of the product in the drying chamber 1 through the access opening 2 and the door 3 was securely closed. The fan 8 was activated to circulate the drying medium through the drying chamber 1 at a sufficient mass flow rate to push the drying medium onto the exposed surface of the product at a rate of about 2 M per second. This speed was maintained during all four stages of the drying process. The inlet valve 1 1 and the outlet valve 14 were closed to confine the drying medium within the duct 7 and the drying chamber 1. The heater 7 was activated to increase the temperature of the drying medium of the first fixing point temperature. The relative humidity of the drying medium in the drying chamber 1 was allowed to increase to the first relative humidity setting point. In this stage, the first phase was completed, and the second phase was started. Immediately after the start of the second phase, the inlet valve 11 and the outlet valve 14 were operated in order to maintain the relative humidity of the drying medium in the drying chamber 1 substantially constant at the first attachment point, and the heater was controlled to maintain the temperature of the drying medium in the drying chamber substantially constant for the duration of the second phase. The fixings of valves 11 and 14 were initially determined using the Modulation index formula. Once the inlet and outlet valves 11 and 14, respectively, were set at the beginning of the second stage, no further adjustment was necessary, and the relative humidity of the drying medium in the drying chamber tended to remain substantially constant. The process moved from the second to the third stage when the relative humidity of the drying medium of the drying chamber 1 began to decrease, or began to decrease more rapidly than the reduction during the latter part of the second phase.

During the third phase, the inlet and outlet valves 1 1 and 14 were controlled to maintain the relative humidity gradient between the drying medium between the drying chamber 1 and that of the product, so that the difference between the humidity relative to the drying medium and the product did not exceed a value, which could result in damage to the structural integrity of the product as already described. This was achieved by continuously varying the settings of the inlet and outlet valves 1 1 and 14 to increase the speed at which the drying medium is added to the recirculation drying medium. During the fourth phase, as the relative humidity of the drying medium in the drying chamber begins to approach asymptotically to the predetermined value of the relative humidity for the drying medium, the inlet and outlet valves 11 and 14, and the heater 9 were controlled and set to maintain the rate at which the fresh drying medium is added to the recirculation drying medium and the heat was added to the drying medium, to maintain the relative humidity of the drying medium substantially at the moisture value relative default. The relative humidity of the drying medium was maintained at the predetermined relative humidity value for a sufficient time until the equilibrium relative humidity of the product being dried was at a value corresponding to the desired final water content of the product. Returning now to Figure 6, which illustrates the parameters of the drying medium during the fourth phase drying process, wherein apple slices were dried to a final water content of about 5.5% by weight. The water activity of the dried apples was 0.272. The apples, which were dried in the procedure in Figure 6, were of the variety I DARED, and were removed from the cold storage, where they were approximately six months. The apples were cut into slices with a thickness of about 3 mm and were loaded into the drying chamber in the two trays 4. The total nominal surface area of the product exposed to the drying medium was 19 M ^. The product loads in the two trays were arranged so that the length of the charges in the direction of air flow through the drying chamber 1, mainly in the direction of the arrow A was as short as possible to reduce at the minimum the relative humidity gradient of the drying medium through the product. The drying medium was circulated through the drying chamber 1 at a sufficient mass flow rate to cause the drying medium to pass over the exposed surface area of the product at a rate of about 2 M per second. A more detailed discussion of the dried apple slices is given below with reference to Table 1. Briefly, the temperature of the drying medium during the first phase of the drying process was allowed to increase to a first temperature setting point of about 60 ° C. The relative humidity of the drying medium was allowed to increase to a first fixing point of about 55%. At the end of the first phase, the equilibrium relative humidity of the product was approximately 93%. During the second phase of the process, the temperature remained substantially constant at the first fixing point, and for most of the second phase, the relative humidity of the drying medium remained substantially constant at around 55%. At the end of the second phase, the relative humidity of the drying medium fell approximately 50%, and the equilibrium relative humidity of the apples was approximately 84%. During the second phase, the drying medium was exchanged with the atmosphere and the speed at which fresh air was added to the drying medium was about 2% and the mass flow rate of the drying medium. During the second phase, the difference between the relative humidity of the drying medium and the relative humidity of the product did not exceed a relative humidity of 35%. During the third stage of the drying process, the relative humidity of the drying medium was dropped at a rate such that the difference between the relative humidity of the drying medium and the equilibrium relative humidity of the apples did not exceed a relative humidity of 47%. In order to achieve this rate of exchange of drying medium with the atmosphere increased gradually during the third phase so that at the end of the third phase, the fresh air added to the drying medium at the rate of approximately 3.5% of the speed of mass flow of the drying medium. During the third phase, the temperature of the drying medium remained substantially constant at about the value of the first fixing point, particularly around 60 ° C, and gradually increased at the end of the third phase at a temperature of about 61 ° C. At the end of the third stage, the relative humidity of the drying medium was approximately 13%, and the equilibrium relative humidity of the apple slices was approximately 60%. During the fourth phase, the relative humidity of the drying medium was dropped, and asymptotically approaching a predetermined value of about 7%. The relative humidity of the drying medium was retained substantially at the predetermined value of 7% over a period of about 40 minutes. These slices of dried apples, finally produced with an equilibrium relative humidity value of about 38%, which corresponds to the desired final water content of about 5.5%, and the water activity about 0.272%. During the fourth phase, the temperature remained substantially constant at about 61 ° C. The fall in temperature in the graph A at the end of the fourth phase is the result of the door 3 of the drying chamber 1 that is opened for the elimination of the dried apples. At the end of the fourth phase, the difference in relative humidity of the drying medium and the equilibrium relative humidity of the product was approximately 30% relative humidity. Figure 7 illustrates two graphs, namely, Graph A of temperature, Graph B of relative humidity of the drying medium of the other example of the four-phase dehydration process according to the invention, wherein apple slices were dried ( Cultivate Jonagold) with a thickness of 3 mm. Although the apple slices were dried in this embodiment of the invention they are of a variety different from the I DARED apples, which were dried in the example of the method according to the invention described with reference to Figure 6, the structure of General cell and other structural characteristics of the two types of apple are substantially similar. As can be seen in Figure 7, the period for the drying process according to this example of the invention was about 2 1/4 hours. This was significantly less than about the 5 hours taken by the procedure described with reference to Figure 6. The reason for the shorter drying time in the procedure of Figure 7 is that it greatly represents the fact that the exchange rate of the drying medium with fresh dry medium was approximately double through the procedure. Another contributing factor to the reduced drying time was the fact that the temperature of the drying medium was allowed to gradually increase from 60 ° C to about 64 ° C during the last half of the third phase, and the fourth phase of the process. Due to the increase in the exchange of drying medium with the fresh drying medium, the relative humidity of the drying medium only reached a maximum value of approximately 49%. although the maximum value of the relative humidity, in 49% is less than the maximum value of approximately 55% of the procedure of Figure 6, the lower value of the maximum relative humidity remained sufficient to avoid damage to the cellular and structural integrity of the product, and also had the effect of accelerating the rate of elimination of water from the product in both the second and the third phases. However, the experiments that were carried out indicate that any significant reduction in the maximum value of the relative humidity much lower than 49% does not reduce the drying time of the process. In reality, the drying time at the lower maximum values of relative humidity can be either similar to that of Figure 7, or it can be increased. Very significantly at maximum relative humidity values much lower than 49%, the damage to the cellular and structural integrity of the product will be enormously evident. This is believed to be caused by excessive differences between the relative humidity of the drying medium and the equilibrium relative humidity of the product. Thus, in general, it has been found advisable to carry out the processes according to the invention with a maximum relative humidity value of the drying medium in the range of 50% to 60%, and preferably in the range of 50% at 55%. In the example of the method described with reference to Figure 7, the equilibrium relative humidity of the apple slices was not verified. However, it is believed that the equilibrium relative humidity curve of the product could substantially follow the equilibrium relative humidity curve of the product of Figure 6, but appropriately modified to represent the shortest drying time. The graphs of the temperature of the drying medium and relative humidity and relative humidity of the product during the drying procedures of fruits and vegetables in different apples, using the four-stage drying process according to the invention, although not shown , are substantially similar to those illustrated in Figures 6 and 7. In general, the only differences are in the drying times, and the maximum values of temperature and relative humidity, which depend on the product being dried and the treatment which products are subjected before drying, as well as the final desired water content of the product. However, in general, the maximum relative humidity value of the drying medium could lie within the range of 50% to 55%, and the initial maximum value of the temperature of the drying medium, in general, could be in the range of 60 ° C to 70 ° C, and in the last part of the drying cycle, typically, towards the end of the third stage, and during the fourth stage, the temperature can be allowed to increase to a maximum of about 65 ° C.

In order to make a comparison between the product of the invention and another dry product, which were dried by other known techniques, the apple slices, which were dried using the four-phase procedure described, referring to the Figure 6, were compared with similar apple slices, which were dried through freeze drying and conventional forced air drying. Table 1 establishes the results of the analysis, which was carried out on dried products through the three dehydration procedures as follows: the water content of the apple product (P% by weight), the dry content of the apple product (including the flavoring compound) (100 -% by weight), water activity (A), ascorbic acid (Vitamin C) content in% by weight, the results of a visual inspection of the cell structure of the product, the fraction (F) of the compounds eluted at a temperature range of 0 to 200 ° C, the ratio (R- |) of the compounds eluted between 0 to 40 ° C in an amount of dry product corresponding to 100 g of dry matter, to compounds eluted between 0 40 ° C for an amount of the initial apple corresponding to 100 g of dry matter, the ratio (R2) of the compounds eluted between 100 and 150 ° C for an amount of dry product corresponding to 100 g of dry matter, to the products eluted between 100 and 150 ° C for an amount of the initial apple corresponding to 100 g of the dry matter. the ratio (R3) of the compounds eluted between 150 and 200 ° C for an amount of dry product corresponding to 100 g of dry matter, to the compounds eluted between 150 and 200 ° C for an amount of the initial apple corresponding to 100 g of the dry matter, the ratio (R) of the compounds other than water eluted between 0 and 200 ° C for an amount of dry product corresponding to 100 g of dry matter, to compounds other than water eluted between 0 to 200 ° C for an amount of the initial apple corresponding to 100 g of dry matter, and the ratio R3 / R1 Table 1 IDARED STORAGE APPLES It can be seen from Table 1 that the dried product according to the invention retains a higher level of ascorbic acid content (vitamin C) and a higher content of the compounds eluted at low temperature. These compounds eluted at low temperature, in general, are aromatic compounds. Furthermore, as discussed below with reference to Figures 2 to 5, very little or no cell damage was detected in the dried product according to the invention, while the cell damage was clearly visible in the products. that were dried by freezing and dried with forced air. The color and texture of the dried product according to the dehydration process of the invention, closely matches the color and texture of the product before being dried, which the color and texture of the dried products did using the others two drying procedures. Figures 2 and 5 are shown in an enlarged range, the results of the microscopic analysis of the cells of the apple slices before drying and after drying using the three drying procedures discussed with reference to Table 1. Figures 2 (a) and 2 (b) illustrate portions of an apple slice before being dried. Figure 2 (a) illustrates the cell structure in an area of the apple slice shell, while Figure 2 (b) illustrates the cell structure of the apple slice pulp area, in other words, an inner portion of the slice of the apple. Figures 3 (a) and 3 (b) illustrate portions of the apple slices in the area of the shell and the pulp area, respectively, after drying through the four-stage drying process according to the invention . Figures 3 (c) and 3 (d) illustrate portions of the area of the shell and the area of the pul, respectively, of apple slices, which were dried using the four-phase procedure according to the invention and subsequently rehydrated. Figures 4 (a) and 4 (b) illustrate portions of the shell area and pulp area, respectively, of the apple slices, which were freeze-dried. Figures 4 (c) and 4 (d) illustrate portions of the skin area and the pulp area, respectively, of apple slices, which were freeze dried, and subsequently rehydrated. Figures 5 (a) and 5 (b) illustrate portions of the shell area and pulp area, respectively, of the apple slices, which were dried using the normal forced draft method. Figures 5 (c) and 5 (d) illustrate portions of the area of the rind and the pulp area, respectively, of apple slices, which were dried by the normal forced drying method, and subsequently rehydrated . All the microscopic analyzes in the area of the shell of the apple slices were carried out at an amplification factor of 280X. all microscopic analyzes of the pulp area of the apple slices were performed at an amplification factor of 140X. It should be noted that the analyzes were performed on different slices. However, a valid comparison between the slices can still be made. Comparing the area of peel of the apple slices before and after drying using the procedure according to the invention, mainly the illustrations of Figures 2 (a) and 3 (a), it can be seen that very little or no no damage to the cell of the cellular structure of the apple slices in the area of the shell during the drying process according to the invention. In addition, by comparing the area of the peel of the apple slice as shown in Figure 3 (c) which was dried during the procedure according to the invention and subsequently rehydrated, it can be seen that the cellular structure after the rehydration returns substantially to its structure prior to drying. The walls of the cell have a substantially normal convex shape, and the cell membrane of each cell in general is in its normal position adjacent to the cell wall. In addition, a waxy layer on the surface of the shell and visible color components with several of the cells adjacent to the shell are substantially undamaged, while a significant disturbance may be detected in the corresponding areas of the dried product by the procedures of freeze drying and air flow. The solid lines of Figures 2 to 5 illustrate the walls of the cells, and the partially interrupted lines illustrate the membrane of each cell. In Figures 2 (a) and 2 (b) only the cell walls shown through the solid line are visible. The reason for this is that the membrane in any fresh product, or a product before dehydration, will generally be adjacent to the cell wall. Thus, in the portions of the apple slices illustrated in Figures 2 (a) and 2 (b), the membrane that is adjacent to the cell wall is not visible in these two illustrations. Ideally, if the product that is going to be dehydrated to its shape before being dried, the membrane and cell wall of each cell should match. While part of the membrane of some of the cells of the shell area of the rehydrated apple slices of Figure 3 (c) has not completely returned to the cell wall, in general, the membrane and the cell wall in most of the cells coincide.

Similarly, much of the same conclusion may arise from the comparison between Figures 2 (b), 3 (b) and 3 (d). In Figure 3 (b), it can be seen that very little or no damage occurred to the cellular structure of the pulp area of the apple slice after being dried, according to the invention and after rehydration, the pulp area of the apple slice substantially returned to normal. In general, in most cells virtually the entire membrane returned to the walls of the cell. A comparison between Figures 2 (a) and 2 (b) on the one hand and Figures 4 (a) to 4 (d) on the other hand shows that as a result of freeze drying there is significant damage to the cells both in the area of the peel as in the pulp area as a result of freeze drying. Not only were the cells damaged, but also the membranes of the cells were misplaced during freeze drying. The degree of damage can be clearly seen in Figures 4 (c) and 4 (d), where after rehydration, cells in the shell area failed to return to normal form. In Figure 4 (d), it can be seen that while some of the cell walls partially took the convex form, which had previously been freeze-dried, virtually all cells in the membrane failed to return to normal, and they remain substantially wrinkled inside the cell. In addition, the intercellular spaces are generally enlarged in the freeze-dried material as a consequence of the freezing process. The comparisons between Figures 2 (a) and 2 (b) on the one hand, and Figures 5 (a) to 5 (d) on the other hand, show a result a little if my lar to that of the comparison of the Figures 2 and 4. As can be seen from Figure 5 (a), a substantial amount of damage occurred to the cell in the area of the apple slice shell, as a result of the drying procedure of the apple. forced normal. Broken cell walls were clearly visible in various places of the product dried by forced air. This is emphasized more in Figure 5 (c) after rehydration, when cells in the area of the apple slice shell failed to return to normal, and in addition, in all cases, the membrane failed to return to the cell wall, and remain substantially wrinkled inside the cell. In Figure 5 (b), the damage of the cell in the pulp area of the apple slice after the normal forced air drying procedure was less apparent. However, after rehydration of the pulp area, the cells in the apple slice failed to return to normal, since, as can be seen in Figure 5 (d), in all cases In some cases the membrane failed to return to the cell wall, and in addition, the cell walls failed to regain their normal convex shape. This failure of the cells to assume their original convex shape shows that the turgor of the fresh product has been irreversibly damaged. The dried tropical fruit materials, obtained using three technologies, were tested. The dried tropical fruits, which were dried according to the invention, were dried using a four-phase dehydration process, which is substantially similar to that described with reference to Figure 6. The other two drying technologies were dried by freezing and drying by conventional air flow, which is identical to the normal forced air drying procedure to which the apple slices are referred in Table 1. The freeze-drying process is also identical to the freeze-drying process to which the apple slices presented in Table 1 were subjected. The dried materials included banana, mango, pineapple, kiwi, papaya, and jengi bre, which were prepared according to the four phase dehydration process of the invention, prepared in the dry material by airflow in I SK (I nstitute of Pomology and Floriculture) of Skierniewice, Pol onia, and the freeze-dried material produced in I SK. The dried product was subjected to organoleptic, physical and chemical analyzes. A sensory analysis of fresh fruit slices, and dried fruits dried according to the invention, dried through conventional flow drying and freeze drying, and sliced rehydrated fruits were carried out. fruits with the use of a classification method. The method for the tests, an unstructured linear scale (a segment in the straight line, with a length of 100 mm, with the appropriate descriptions at the edges, defining if the evaluation matter is wrong). The people who carried out the test marked their classifications on the scale, corresponding to the sensation experienced; immediately, the results of the test were converted to numerical values, assuming the full scale of the scale that is 10 units i maginaria. Tables 2a-2f show the results obtained based on the averages for 10 people, each of which received coded displays in a different order.

Table 2a Bananas - a summary of the average organoleptic classifications Quality characteristics: 1. Smell of banana (O-imperceptible 10-under) 2. Weird smell (O-imperceptible, 10-intense) 3. Color - degree of (0-light color, no-coffee-10-coffee grinding) 4. Hardness (0-soft 10-hard) 5. Brittle (0-elastic, 10-brittle) 6. Flavor of banana (O-imperceptible, 10-thigh) 7. Strange flavor (O-imperceptible, 10-under) 8. Overall impression (0-low quality 10-high quality Table 2b Mango - a summary of average organoleptic classifications Quality features: 1. Mango smell (O-imperceptible 10-intense) 2. Strange smell (O-imperceptible, 10-intense) 3. Color - grade (light 0-color, non-coffee-bearing 10-coffee) 4. Hardness (0-soft 10-hard) 5. Crisp (0-elastic, 10-brittle) 6. Mango flavor (O-imperceptible, 10-under) 7. Strange taste (O-imperceptible, 10-intense). Overall impression (0-low quality 10-high quality Table 2c Pineapple - a summary of organoleptic classifications Quality characteristics: 1. Pineapple smell (O-imperceptible 10-intense) 2. Strange smell (O-imperceptible, 10-intense) 3. Color - grade (light 0-color, no-coffee 10-coffee) 4. Hardness (0-soft 10-hard) 5. Crisp (0-elastic, 10-brittle) 6. Pineapple flavor (O-imperceptible, 10-intense) 7. Strange taste (O-imperceptible, 10-under) 8. Overall impression (0-low quality 10-high quality Table 2d Kiwi - a summary of the average organoleptic classifications Quality features: 1. Smell of kiwifruit (O-imperceptible ble 10) 2. Strange smell (O-i measurable, 1 0-intense) 3. Color - degree of (light 0-color, no-coffee 10-coffee) 4. Hardness (0-soft 1 0-hard) 5. Crisp (0-elastic, 1 0-brittle) 6. Kiwi flavor (O-imperceptible, 1 0-i ntenso) 7. Strange taste (O-imperceptible, 10-intense) 8. I general impression (0-low quality 10-high quality Table 2e Papaya - a summary of average organoleptic classifications Quality features: 1. Papaya smell (O-imperceptible 10-intense) 2. Strange smell (O-imperceptible, 10-unlikely) 3. Color - grade (light 0-color, non-coffee-bearing 10-coffee) 4. Hardness (0-soft 10-hard) 5. Crisp (0-elastic, 10-brittle) 6. Papaya flavor (O-imperceptible, 10-intense) 7. Strange taste (O-imperceptible, 10-under) 8. Overall impression (0-low quality 10-high quality Table 2f Ginger - a summary of average organoleptic classifications Quality characteristics: 1. Smell of ginger (O-imperceptible 10-intense) 2. Weird smell (O-imperceptible, 10-intense) 3. Color - degree of (0-light color, no-coffee 10-coffee) 4 Brittle (0-elastic, 10-brittle) 5. General impression (0-low quality 10-high quality Note: Since ginger is a species, organoleptic classifications of ginger flavor and strange taste were not determined.

A numerical comparison of the level of chromatographic fingerprints for volatile compounds produced by the six previous fruits and tubers, and passion fruit (passion fruit), in the indicated temperature scales is shown in Table 3a. The data are given in units integrated by 100 g of the tested material and per liter of air. The results are an average taken for the three measurements. This analysis was performed on an H P gas chromatography equipment with an FI D sensor.

Table 3a Table 3a (cont.) Another numerical comparison of the level of chromatographic fingerprints for volatile compounds produced by the same materials is shown in Table 3b. The data in units of integration per 100 g of the material tested per liter of air passing through it were recalculated in terms of 1 00 g of the dry mass of the material tested. The results are averages of the three measurements. Table 3b Table 3b (cont.) The gas chromatographic (GC) strips illustrated in Figures 8 to 11 were prepared from slices of banana before, and after drying using the three drying procedures discussed with reference to Table 1. The gas chromatographic fingerprints illustrated in Figures 12 to 14 were also prepared from banana slices after they were subsequently rehydrated. The gas chromatographic fingerprints were prepared in an H P gas chromatography with an FI D sensor on the temperature scale of the ambient temperature up to 200 ° C. The period of each test to prepare the corresponding fingerprint is plotted on the X axis in units of minutes. During the test period, the temperature of the sample slices was increased in a controlled manner from room temperature to 200 ° C. The y-axis is a measure of the chromatographic response measured by gas chromatography, the scale of this response is in machine units, and the scale is adjusted for each test to match the measured peak. The numbers associated with the peaks in the tracks are the retention times in minutes for the release of the respective volatile compounds. These retention times together with the temperature profile used for the tests make it possible to associate each peak ambiguously with a specific molecular volatile compound. Figure 8 illustrates the gas chromatographic fingerprint of a banana slice before dehydration. Figure 9 illustrates the gas chromatographic fingerprint for a slice of banana that was dried through the four-phase process according to the invention. Figure 10 illustrates the chromatographic gas strut for a banana slice, which was dried through the conventional airflow method. Figure 1 1 illustrates the gas chromatographic fingerprint for a banana slice, which was dried by the freeze-drying process. Figure 1 2 illustrates the chromatic gas fingerprint of a banana slice, which was rehydrated after being dried by the four-phase process according to the invention. Figure 1 3 illustrates the chromatographic fingerprint for a banana slice which was rehydrated after being dried by the conventional air flow drying method. Figure 14 illustrates the gas chromatographic fingerprint for a banana slice that was rehydrated after being dried by the freeze drying process. The flavor and aroma characteristic of foods eaten in their raw state are dominated by volatile compounds which are eluted, mainly, released or activated at temperatures of up to 40 ° C, in other words, up to normal body temperature . Therefore, the similarity between the chromatographic signature of elution of a fresh fruit or vegetable, in other words, a fruit or vegetable that has not been dried and the dried product, is a strong indication of how well the aroma is retained and the taste of fresh fruit during a drying procedure. A comparison between the gas chromatographic fingerprint of Figure 8, mainly the fingerprint of the fresh banana with the chromatographic fingerprint of the gas of Figure 9 of the dried banana by the method of the invention, illustrates that the dried banana by the procedure according to with the invention it retains substantially all the compounds that are eluted at temperatures up to 40 ° C. Furthermore, it can be seen from the imprint of Figure 12, that the rehydrated banana, which was dried through the process according to the invention, also retains substantially all the compounds that are eluted at temperatures up to 40 ° C. . On the one hand, a comparison of the traces of Figures 10 and 11, which illustrate the traces of the banana that was dried by the conventional air flow drying process and the freeze drying process, respectively, and the footprint of the Figure 8, shows that after drying the flow of conventional air and freeze drying, a significant number of the compounds that are the uidos at temperatures of up to 40 ° C that were present in the banana before being dried, are absent in the product after drying. Similarly, a comparison between the strike of Figure 8 and Figures 1 3 and 1 4 illustrating the rehydrated banana after drying by conventional air flow and freeze drying, respectively, shows a somewhat different result. to that of the comparison of the huells of Figure 8, on the one hand and Figures 10 and 1 1 on the other hand. In addition, it can be seen from the footprint of Figure 9, that the dried banana, which was dried through the procedure according to the invention, has prominent gas chromatographic peaks at retention times of 6.1 10 and 7,374 minutes The main fraction of volatile compounds were compounds that evaporate in the temperature range of 40 ° C to 100 ° C. In fresh fruits, this fraction contained predominantly: methyl butanoic acid ester (RT = 7.3); a compound not identified with RT = 1 0.2; butanoic acid propyl ester (RT = 1 1 .9); 2-methylbutanol and / or 3-methyl butanol (RT = 14.8); Hexyl ester of ethanoic acid (RT = 16.5). Hexanol (RT = 1 9.3) was the main constituent of the fraction from 100 ° C to 1 50 ° C. In the dried banana, which was dried through the three drying procedures, the main constituents of the 40 ° C to 1 00 ° C fraction were: ethanol (RT = 6.1); methyl ester of butanoic acid and 2-methyl butanol and / or 3-methylbutanol. In the dried banana, which was dried through the drying process of the invention, the main components of the aforementioned fraction were a compound with an RT = 11.0 (probably isobutyl isobutanoic acid ester) and a compound not identified with RT = 1 7.6. In the dried banana, which was dried through the freeze-drying process, in the fraction from 40 ° C to 1 00 ° C, methyl butanoic acid ester (RT = 7.3) and a compound not identified with RT were dominant. = 10.5. After the rehydration of the banana which was dried by the three drying procedures, a drop in the level of ethanol in the aroma was detected, the dominant compound was still methyl butanoic acid ester (RT = 7.3). In summary, the proportion of the low boiling fraction (up to 40 ° C) was increased in the aroma of both the rehydrated banana which was both dried by the procedure according to the invention and dried by the drying process. by freezing.

Figures 1-5 to 18 illustrate gas chromatographic fingerprints of the I DARED apple slices, which were prepared in a manner similar to that of Figures 8 to 11. Figure 15 is a gas chromatographic fingerprint of an apple slice before being dried. Figure 16 is a gas chromatographic fingerprint of an apple slice that was dried by the four phase process according to the invention. Figure 1 7 is a gas chromatographic fingerprint of an apple slice that was dried by the conventional airflow drying method, and Figure 1 8 is a gas chromatographic step of an apple slice that was dried by the freeze drying process. A comparison between the four traces of Figures 1-5 to 18 indicates that as in the case of banana slices, the apple, which is dried by the process according to the invention, retains a substantial amount of the compounds volatile which are the uidos at a temperature of up to 40 ° C, while apples that were conventionally dried by conventional air flow and dried by freezing did not retain the same amount of such compounds. However, a significant aspect that can be seen through a comparison between the traces of Figures 15 and 18 is the fact that the apple, which was dried through the freeze-drying process, shows the development of significant peaks in the higher temperature range, in other words, the temperature varies to 200 ° C, which, in general, tends to be associated with the development of off-flavors. Such peaks are not present in the dried apple slice by the process according to the invention. It can also be seen from the strike of Figure 16, that the apple dried by the procedure according to the invention, has prominent gas chromatographic peaks in retention times of 6.1 01, 1 0.186 and 1 1 .834 my nutos. Figures 1 to 25 are gas chromatographic fingerprints for mango slices that correspond to the gas chromatographic fingerprints of the banana slices of Figures 8 to 14. In other words, Figure 19 is a chromatographic gas chromatograph. Mango before drying, Figure 20 is a handle strut dried through the four-stage process according to the invention, Figure 21 is a handle imprint dried through the conventional airflow drying process, Figure 22 is a fingerprint of the dried handle by the freeze drying process, Figure 23 is a strike of the handle which was rehydrated subsequent to being dried by the process according to the invention, Figure 24 is a footprint of mango that was rehydrated subsequent to drying by the conventional airflow drying procedure, and Figure 25 is a mango shoot that was rehydrated subsequent to medium drying Follow the freeze drying procedure. The comparisons between the traces of Figures 19 and 23 produce conclsions substantially similar to those presented in the comparisons made between Figures 8 to 14 of the banana as already discussed. Furthermore, it can be seen from Figure 20 that the dried handle, which was dried by the process according to the invention, has prominent gas chromatographic peaks at 6,181 and 1 2,771. The main fraction of the volatile compounds in the mango are compounds that evaporate in a range of temperatures from 40 ° C to 100 ° C. The dominant compounds that will be found in this fraction for fresh fruit are: compounds not identified with RT = 1 2.5, RT = 1 2.8 (probably butanol), RT = 1 3.1, RT = 14.2 and RT = 1 7.0. The compound with RT = 1 2.7 remains in the primary compound emitted by the dried mango which was dried by the three drying procedures. Nevertheless, in the aromas of dried mango, which was dried through the process according to the invention, there is also a large amount of ethanol (RT-6.81). After rehydration of the dried mango through the method of the invention, three compounds dominated, one with RT = 9.2 (probably propanol), the other two with RT = 12.5 and RT-16.6. After rehydration of the mango, which was dried by the conventional airflow drying process, butanol also dominated (RT = 12.8). After rehydration of the mango, which was dried by the freeze-drying process, the rehydrated mango became very aromatic, with a large precipitation of a compound with RT = 4.0 (methyl ester of ethanoic acid) in the fraction up to 40 ° C. This rehydrated mango also exhibited compounds with RT = 5.1 (methanol), RT = 9.2 (propanol), RT = 12.3 and RT = 16.5 in the fraction of 40 ° C at 100 ° C, and compounds with RT = 27.6 and RT = 29.9 in the 150 ° C to 200 ° C fraction. Figures 26 to 32 illustrate gas chromatographic fingerprints for papaya, which also correspond to the chromatographic fingerprints of Figures 8 to 14. In other words, Figure 26 is a papaya fingerprint before being dried, Figures 27 to 29 are papaya footprints that have been dried by the process according to the invention, the conventional airflow drying process and the freeze drying process, respectively, and Figures 30 to 32 are papaya footprints that have been rehydrated after being dried by the process according to the present invention, the conventional air-flow drying process and the freeze-drying process, respectively. A comparison between the strips of Figures 26 to 32 yields conclusions substantially if my eyes compare to those presented in the comparison between the traces of Figures 8 to 14 in relation to the banana. In addition, dried papaya, dried by the process according to the present invention, has predominant gas chromatographic peaks at retention times of 6.254, 7.941 and 9.323. Figures 33 to 39 illustrate gas chromatographic fingerprints for kiwi slices, also correspond to Figures 8 to 1 4. In other words, Figure 33 is a fingerprint of the kiwi before being dried, Figures 34 to 36 are fingerprints of the kiwi after being dried by the process of the invention, the drying procedure by conventional air flow and the freeze drying process, respectively, and Figures 37 to 39 are traces of the kiwi after being rehydrated subsequent to drying by the process according to the invention, the conventional air flow drying process and the freeze drying process, respectively. A comparison between the traces of Figures 33 to 39 produces conclusions substantially similar to those presented from the results of the presence of the comparison of the strips of Figures 8 to 14 for the banana. Furthermore, it can be seen from Figure 34 that the dried kiwifruit, which was dried by the process according to the present invention, has prominent gas chromatographic peaks at retention times of 6.344, 7.946, 8.649 and 9. 336. Figures 40 to 46 illustrate gas chromatographic fingerprints of ginger, which correspond to the fingerprints of Figures 8 to 14. In other words, Figure 40 shows a fingerprint of the ginger before drying, Figures 41 to 43 After using the procedure according to the invention, the conventional air fl ow drying process and the freeze drying process, respectively, and Figures 44 to 46 We use the eggs of the jengi bre after having been rehydrated subsequent to drying by the process according to the invention., the conventional air fl ow drying procedure and the freeze drying process, respectively. Comparisons between the traces of Figures 40 to 46 produce conclions substantially similar to those presented in the comparison of the traces of Figures 8 to 14 for bananas. Furthermore, it can be seen from Figure 41, that dried ginger, which was dried by the process according to the invention, has prominent gas chromatographic peaks at retention times of 5,741, 6,356, 7,996, 8,496, 9,407. , 10,006 and 11,213 minutes. Figures 47 to 53 illustrate pineapple gas chromatographic fingerprints, which correspond to the gas chromatographic fingerprints of Figures 8 to 14. In other words, the fingerprints of Figure 47 are pineapple before drying. The traces of Figures 48 to 50 are pineapple, which was dried by the process according to the invention, the conventional airflow drying process and the freeze drying process, respectively, and the footprints of the Figures 51 to 53 are pineapple, already rehydrated, before being dried by the process according to the invention, the conventional air flow drying process and the freeze drying process, respectively. A comparison between the traces of Figures 48 to 53 produces conclusions similar to those presented for the comparison between the traces of Figures 8 to 14 with respect to bananas, and in addition, it can be seen from Figure 49, that the Pineapple dried by the process according to the invention has prominent gas chromatographic peaks at a retention time of 6,104 minutes. In the pineapple before being dried, the most intense case was the fraction up to 40 ° C, with the compound RT = 4.9 (ethyl ethanoate) dominating. In the fraction from 40 ° C to 100 ° C, the predominant compounds were RT = 7.4 (methyl ester of butanoic acid), RT = 8.1 (methyl ester of 2-methylbutanoic acid) and RT = 14.0 (methyl ester of hexanoic acid). In the dried pineapple, which was dried by the conventional airflow drying procedure, the main component was a compound not identified with RT = 12.6 and in the dried pineapple, which was dried by the process according to the invention , the main component was ethanol (RT = 6.1). The dried pineapple, which was dried by the freeze drying process, mainly contained the compounds with RT = 12.6. After the rehydration of the dried product, which was dried by the conventional air flow drying process and the freeze drying process, there was an increase in the proportion of the compounds of the order of up to 40 ° C of the fraction . In the case of the rehydrated pineapple, which was previously dried by conventional air flow, the main compounds were compounds not identified with RT = 9.2 and RT = 16.5. In addition, in the rehydrated pineapple, which was dried by the conventional air flow drying procedure, there were unidentified compounds belonging to the fraction from 1 50 ° C to 200 ° C, which were characterized by RT = 27.6 and RT = 29.8. The main compounds in the rehydrated material, which had been previously dried by a freeze-drying process were the compounds with RT = 2.8, RT = 3.8 (ethanoic acid methyl ester), RT = 5.0 (ethyl ethanoate), RT = 6.1 (ethanol), RT = 1 1 .2 and RT = 14.9 (3-methyl butanol). Figures 54 to 60 illustrate gas chromatographic fingerprints of passion fruit slices, which correspond to the gas chromatographic fingerprints of Figures 8 to 1 4. In other words, Figure 54 illustrates a passion fruit strut before being dried , Figures 55 to 57 illustrate traces of passion fruit dried by the process according to the invention, the conventional air flow drying process and the freeze drying process., respectively, and Figs. 58 to 60 use rattan passion fruit being rehydrated after having been dried by the process according to the invention, the conventional air flow drying process and the freeze drying process, respectively.

A comparison procedure between the fingerprints of Figures 55 to 60 produces conclusions substantially similar to those presented in the comparison of the fingerprints of Figures 8 to 14 for bananas. In addition, it can be seen from Figure 55, that dried passion fruit, which was dried by the process according to the invention, has prominent gas chromatographic peaks at retention times of 6,367, 7,983, 8,682 and 9,375 minutes. In the previous analysis, which was carried out with reference to Figures 8 to 60, it should be noted that the various compounds that have been identified have been identified based on the comparison of retention times with reference times, and based on in the data that are available in the literature. The compound with the retention time with 27.0, which is visible in gas chromatography, is an ethyl ester of octanoic acid, which is used as a reference substance. Furthermore, it should be noted that the abbreviation "RT" in the above discussion with reference to Figures 8 to 60 indicates "retention time". The results of the analysis of volatile compounds using gas chromatography give evidence to the influence of drying technology on the composition of the level of aromatic compounds in dry materials. The main fraction of the volatile compounds consists of compounds that evaporate at a temperature range of 40 ° C to 1 00 ° C. In all dried materials, due to technological processing, a fault occurs at the level of aromatic substances. However, the dried fruits and vegetables, which were dried by a process according to the invention, have the highest level of aromatic compounds for each of the fruit and vegetable species. After rehydration, an increase in the content of volatile compounds occurs in the case of mango and pineapple. This is the largest case of mango and pineapple, which have been dried by the freeze drying process. There is also an increase in the content of volatile compounds in the rehydrated banana, and this increase is the largest in the case of the rehydrated bananas, which had been previously dried by the process according to the invention. At the same time, in the organoleptic classification, the highest level of foreign matter for the banana was observed in the rehydrated banana, while in the case of mango and pine, the highest level of the strange smell was found in the banana. rehydrated mango and banana, which had been previously dried by the freeze-drying process.

A color determination was conducted on each fruit and tuber tested, using a test procedure in accordance with the color meter H unter to L * a * b * and set forth in Table 4.

Table 4 Table 4 (copt.) The dry mass content of each fruit and tuber tested was evaluated by drying the samples to a substantially total dryness. The results are shown in Table 5. The table shows that for most of the fruits tested, the products dried by the four-phase process of the invention could be rehydrated to a water content closer to the water content of the product before. if dried, the product could be dried by the other two drying procedures. The ability of a dry product to be rehydrated to a state that approaches that of the product before being dried is an indication of the retention of the properties of that product, which has previously been dried.

Table 5 Table 5 (copt.) .

The water activity measurements of the above dried fruits and tubers were taken and the results are presented in Table 6. The water activity measurements were taken using an AW-TH ERM 40 activity meter with temperature compensation automatic .

Table 6 The ascorbic acid content of the previous dry fruits and tubers tested, is presented in Taba 7. The presence of ascorbic acid was tested using the CLAP method, Supelco LC-18 column, with the solvent 1% KH PO4, pH = 3 , the flow velocity = 0.8 ml / min. The detection was conducted at a wavelength of 243 nm. A representative sample of the material was taken, which was homogenized in 6% metaphosphoric acid, and then fi ltered. From the solution obtained, the phenol compounds were removed in the column C-18 and then the solution was subjected to chromatography analysis.

CLAP. The retention time of ascorbic acid was equal to 6.31 minutes. In the tested range of ascorbic acid content (from 0.2 to 1.5 mg of ascorbic acid in 100 ml of a solution prepared by injection), the square of the correlation of the ascorbic acid content in the reference solutions and the areas The surface area of the peak is equal to 0.9998.

Table 7 From the previous fruits and tubers, a measure of the content of b-carotene and carotenoids was made, and the level of nitrates and nitrites for banana, mango and pineapple. The result of the comparison is shown in Table 8. The analytical methods used were as follows: carotenoids and b-carotene - method described by Czapski and Saniewski, Experimentia, 39, 1373-1374, 1983; nitrates - potentiometric method, using the ORION apparatus; nitrites - spectrophotometric method, according to Polish PN-92 A-75112 normal.

Table 8 Table 9 shows the results of texture tests on the slices of the previous fruits and tubers, with the exception of passion fruit (passion fruit). Each result is an average of at least 20 measurements. The measurements of the penetration force and the Young's modulus were made using the structural solidity meter I nston 4303 with a sensor with a radius of 3.7 mm. To take the measurements, the perforation of a slice of a given material was placed between two plates with holes with a radius of 16.7 mm. As can be seen from Table 9, most dry products by the dehydration process according to the invention have a Young's modulus between 0.1 1 M Pa and about 0.20 M Pa.

Table 9 Evaluation of organoleptic test results Banana Banana slices dried by the four-phase process of the invention and dried slices by the conventional flow of ai re received similar classifications, both higher than the classifications for slices of pl dried banana by freezing, for the presence of typical banana flavor and absence of bad taste. The slightly different total cl for the material dried by conventional air fl ow is the result of its greater hardness, caused by drying at a content level of 5.5% (see 7.2% for the dried material according to the nvention). The dried banana slices according to the invention were much less brittle than the other dried products tested. In addition, the color of the dried banana slices according to the invention was closer to the color of the banana slices dried by freezing, to the color of the banana slices before drying. After rehydration, due to a comparable water absorption capacity (see Table 6), the dried materials according to the invention and the dried material by the conventional air flow reached a similar level of hardness. At the same time, materials dried by freezing and dried by conventional air flow were characterized by a high degree of soothing and a strongly perceptible foreign odor and a taste after rehydration. They were classified as not pleasant, with an unnatural color and smell. The color classifications are confirmed in the color parameter measurements according to the H unter scale (Table 4).

Handle The material dried by the conventional air flow, received the highest classification for the odor of the handle with the lowest level for the strange smell, slightly higher than the classification of the dried material according to the invention. As the material dried by freezing, the material dried by conventional air flow was characterized by a low degree of clamping, comparable to that of the handle before drying. The material dried by conventional air flow and the dried material according to the invention received different classifications of hardness, reflecting the water content absolutely equal (6.3% and 6.8%, respectively). The dried product according to the invention had a much lower degree of brittleness.

After rehydration, the differences between the various dried materials became more noticeable. In this way, the dried material using conventional air flow drying had a higher level of foreign smell and taste after rehydration, in addition to being harder and lighter in color than the dried material according to the invention. The rehydrated freeze dried material, while retaining a light color comparable to that of the mango before being dried, was characterized by a particularly high level of foreign smell and taste.

Pineapple Of the dried pineapples tested, the dried pineapple according to the invention was characterized by higher organoleptic classifications (Table 2c). In particular, it had an exceptionally strong pineapple odor, similar to that of the pineapple before drying, with almost no strange smell. In addition, it was characterized by its low point of brittleness. The rehydrated pineapple slices, which had been dried according to the invention, were characterized by a hardness close to that of the pineapple slices before drying. This feature is important in the use of dried fruit for the production of breakfast mixes to which liquids are usually added, for example, milk. Also in those pineapple slices, which were rehydrated after having been dried according to the invention, the most intense pineapple aroma was recorded. The highest level of strange smell, as in the case of mango, was observed in the rehydration obtained in the freeze-dried material. These results are in line with those acquired from the analysis of volatile compounds as shown in Figures 9 and 1 2.

Kiwi The kiwi slices dried according to the invention had a low crisp appearance and a high level of kiwi flavor retention. The freeze dried material also had a high level of kiwi flavor retention, but otherwise was light in color and brittle. After rehydration, the structure became too soft and bad taste and odor developed in the freeze dried materials and dried by conventional air flow. The dried kiwifruit according to the invention was superior in all aspects tested in color retention and was classified substantially better than the others in taste and odor after rehydration.

Papaya Papaya slices dried by conventional air flow drying received generally average classifications, while after rehydration received low classifications. The papaya dried according to the invention exhibited a higher intensity of flavor-aroma compounds typical for the papaya before drying, and the lower presence of bad taste and foreign odor. The freeze-dried material received higher classifications in general in the dry state, compared to the conventional dried flow-through material, whereas after rehydration, the density of the compounds responsible for the undesirable taste and odor was significantly increased. . All products of papaya fruit, both in dry form and after rehydration, exhibit a color if n no mention of storage. The rehydrated papaya, which was dried according to the invention, received substantially higher classifications than dried papaya using other procedures.

Ginger Freeze dried slices of jengi exhibited a full color and a high degree of brittleness. The highest level of ginger flavor with almost no extraneous odor was observed in dried materials according to the invention. Relatively good quality was presented by the material dried by conventional air fl ow except for significant lining, which was reflected in the color evaluation and the total heat classification. In all dry products, the density of volatile products gives the typical ginger fragrance, it was reduced after rehydration, while the intensity of the strange odor returned to the typical level for the jengling before drying. The rehydrated ginger, which was dried according to the invention, received a slightly higher total amount compared to the rehydrated ginger, which was dried according to the other techniques.

Color _Table 4 presents the color coordinates determined in the Hunter apparatus L * a * b for various materials before and after drying. The materials dried according to the invention exhibited superior color retention and color stability after rehydration in all cases.

Other Observations Capacity for rehydration The highest capacity for water absorption (rehydration) was shown by the dried papaya and dried ginger according to the invention. In the case of kiwifruit, the dried material by conventional air flow had a slightly higher rehydration capacity than the dried material according to the invention. The freeze-dried material of the various fruits and tubers tested indicated the lowest levels of rehydration capacity compared to the others.

Water activity Water activity measurements (Table 6) indicate that all dry materials tested were completely protected against microbiological deterioration. In this way, these materials can not require any additional treatment to ensure conservation, instead of packaging, due to its high hygroscopicity. The dried pineapple according to the invention had the highest water activity value, which is in line with the dry mass measurements and the organoleptic determinations. The water activity value for all tested materials, dried according to the invention, was less than 0.41, which indicates that they were completely protected against the microbiological disposition.

Ascorbic acid content The results of the tests for the presence of ascorbic acid in the materials before and after drying can be found in Table 7. For dried mango and pineapple according to the invention, there are only insignificant losses of vitamin C during processing. In this way, the handle dried according to the invention, retained approximately 98% of the vitamin C content of the handle before drying. Similarly, the dried cake according to the invention retained 92%. Mango and pineapple slices dried by conventional airflow drying exhibited higher losses of vitamin C, 20% for mango and 16% for pineapple. A comparison of the losses of vitamin C in the dried materials according to the invention and the freeze-dried materials makes it possible to conclude that the proportion of the vitamin C conserved in the initiator is exceptionally high. Since bananas contain a very high level of enzymes native to the oxidized group, drying presented a very strong drop in the ascorbic acid content. The highest preservation rate of ascorbic acid (approximately 1.5%) was found in dried bananas according to the invention. For bananas dried by freezing, the conservation regime was approximately 14%. Bananas dried by conventional air flow had a loss of vitamin C in the range of 98%, meaning that it was almost a complete destruction of vitamin C in this material. The dried kiwifruit according to the invention had virtually no loss of ascorbic acid. In freeze-dried kiwifruit, 80% of vitamin C was preserved.

Presence of carotenoids and beta-carotene The results of the tests, given in Table 8, indicate that all species of tested materials retain a similarly high level of beta-carotene and carotenoids. In this way, each of the drying procedures results in a small loss of these elements. The dried pineapple according to the invention showed superior results in the retention of b-carotene.

Level of nitrates and nitrites The level of nitrates and nitrites in tested fresh and dried materials is below the maximum value accepted by FAO / Word Health Organization and the Polish National Hygiene Office. With respect to the presence of the aforementioned compounds in these materials, they can be considered completely acceptable for the consumption of adults and children.

Compound products using dried materials according to the invention The dried materials according to the invention can be added to composite food preparations. For example, you can add dried apple or banana slices to a mixture that is going to be baked to make a cake. Slices of dried fruit as such or dried fruits in the form of powder can also be advantageously used as additives for sugar syrup, jams, ates, yoghurts, sauces, for example, dressings, gelatinous products, for example, a mixture of dry gelatin and dried fruit or herb particles, etc. After drying, the herbs, species, vegetables and the like are advantageously cut into small particles and possibly mixed with salts or other seasoning materials.

Use of the methods of the invention as a pre-treatment Tests made on various dry materials, for example, apple slices, have shown that the product of the invention has a higher vitamin C content than apple slices. dried by freezing. Due to this high retention of vitamin C content, the procedure of the invention can be used as a previous treatment in order to increase the concentration of the structural components of the material that will be dried, including the vitamin C content. , and to increase the efficiency of another procedure for which the material is to be used, without significant degradation of such components. The process of the invention can therefore be used, for example, for the drying of a culture medium having microorganisms in order to have dry the material with a higher concentration of the component sought in the process. The methods according to other embodiments of the invention can also be performed through the apparatus shown in Figure 1, and this will be readily apparent to those skilled in the art. Since the apparatus of Figure 1, which has been described for carrying out the dehydration process according to the invention, provides the performance of the dehydration procedures of the invention as intermittent procedures, it will be readily apparent to those skilled in the art. In the art, other suitable apparatuses can be provided so that the procedures according to the invention can be carried out as continuous procedures. It is also considered that it is not essential that the same drying medium, subjected to the addition of the fresh drying medium, be used in the complete drying process. For example, it is contemplated that the product can be transported in a production line through a number of different drying chambers, where different drying media could be used. However, in such cases, the temperature and relative humidity of the drying media in general, could be regulated in various drying chambers, so that the change in temperature and relative humidity of the drying medium to which the product is subjected in the transition from one drying chamber to another, could be gradual, and could be substantially similar to that described with reference to Figures 6 and 7. Furthermore, it is contemplated that when the product is transferred from one drying chamber to another in a drying process, the drying medium it can be circulated a number of times through the respective drying compartments, and then it can subsequently be recirculated to the next drying chamber in sequence. It will be appreciated that the dehydration procedures for dehydrating various fruits and tubers, which have been described above, can be varied without departing from the scope of the invention. The described examples of the drying process of the invention have been given purely for purposes of describing the best known method for carrying out the process according to the invention.

Claims

1. A dry product having a water content of less than 20%, characterized in that at least 50% of the cells not adjacent to one side of the product still have a substantially undamaged membrane, and wherein the water present in the product has a Water activity that does not exceed 0.7.

2. The dry product according to claim 1, characterized in that the water present in the product has a water activity does not exceed 0.65.

3. The dry product according to claim 2, characterized in that the water present in the product has a water activity does not exceed 0.6.

4. The dry product according to claim 3, characterized in that the water present in the product has a water activity between 0.2 and 0.5.

5. The dry product according to claim 4, characterized in that the water present in the product has a water activity of between 0.25 and 0.45.

6. The dry product according to claim 5, characterized in that the water present in the product has a water activity between 0.3 and 0.4.

7. A dry product according to any of the preceding claims, characterized in that the water content is less than 10%.

8. The dry product according to claim 7, characterized in that the water content is in the range of 4% to 7%.

9. A dry product according to any of the preceding claims, characterized in that substantially all the cells of the dried product, which were not damaged before drying, remain substantially undamaged after drying. 1 0.

A dry product, according to any of the preceding claims, characterized in that the product is a biological product. eleven .

A dry product, according to any of the preceding claims, characterized in that the product is a dried fruit.

2. A dry product, according to any of the preceding claims, characterized in that the product is a dry vegetable.

3. A dry product, according to any of the foregoing claims, characterized in that the product is in the form of a slice.

14. A dry product, according to claim 1 3, characterized in that the slice before dehydration has a thickness in the range of 1 mm to 10 mm.

5. A dry product, according to claim 14, characterized in that the slice before dehydration has a thickness in the range of 3 mm to 7 mm.

1 6. A dry product according to any of the preceding claims, characterized in that the product contains compounds that are capable of being the liquid at different temperatures, the weight ratio fraction of the compounds eluted at a temperature between 1 50 ° C and 200 ° C to the fraction of compounds eluted at a temperature between 40 ° C and 100 ° C are greater than 0.3.

1 7. A dry product according to claim 1 6, characterized in that the fraction by weight ratio of the compounds eluted at a temperature of 1 50 ° C to 200 ° C to the fraction of compounds eluted at a temperature of between 40 ° C and 100 ° C is greater than 0.5.

18. A dry product according to claim 1 7, characterized in that the fraction by weight ratio of the compounds eluted at a temperature between 1 50 ° C to 200 ° C to the fraction of compounds eluted at a temperature between 40 ° C. C and 100 ° C is greater than 0.6.

19. A dry product according to any of the preceding claims, characterized in that the product contains compounds that are capable of being eluted at different temperatures, the fraction by weight ratio of the compounds eluted at a temperature of between 50 ° C to 200 ° C. ° C to the fraction of compounds eluted up to 200 ° C is greater than 0.25.

20. A dry product according to any of the preceding claims, characterized in that the product comprises cells adjacent to one side of the product, such cells define between the spaces, at least 50% of the spaces are not completely or completely filled with sugar . twenty-one .

A dry product according to any of the foregoing claims, characterized in that the product comprises cells adjacent to one side of the product, such cells define spaces between them, at least 50% of these spaces contain a gaseous medium.

22. The dry product according to claim 21, characterized in that at least 50% of such spaces are filled at a rate of at least 50% with a gaseous medium.

23. The dry product according to any of the preceding claims, characterized in that the product is a banana and the dried product has prominent gas chromatographic peaks at retention times of 6.1 and 7.3 minutes.

24. The dry product according to any of the preceding claims, characterized in that the product is a handle and the dried product has prominent gas chromatographic peaks at retention times of 6.1 and 12.8 minutes.

25. The dry product according to any of the preceding claims, characterized in that the product is piña and the dry product has a promising chromatographic peak of the gas at retention times of 6.1 minutes.

26. The dry product according to any of the preceding claims, characterized in that the product is kiwifruit and the dried product has a promising chromatographic peak of the gas at retention times of 6.3 minutes.

27. The dry product according to any of the preceding claims, characterized in that the product is papaya and the dried product has a prominent chromatographic peak of the gas at retention times of 6.2 minutes.

28. The dry product according to any of the preceding claims, characterized in that the product is ginger and the dried product has a prominent chromatographic peak of the gas at retention times of 6.3, 8.4 and 10.0 minutes.

29. An improved food preparation having as an ingredient a dry food product, characterized in that the dry food product has a water content of less than 20%, the dry food product is a product wherein at least 50% of the cells not adjacent to One side of the product still has a closed membrane, and wherein the water present in the dry food product has a water activity of less than 0.7.

30. A food preparation according to claim 29, characterized in that the food composition is useful as a sauce composition.

31 The dry product having a water content of less than 10%, characterized in that at least 50% of the cells not adjacent to one side of the product still have a substantially undamaged membrane, and wherein the water present in the product has a water activity less than 0.4.

32. The dry product according to claim 31, characterized in that the water content of the dried product lies in the range of 4% to 7%.

33. The dry product according to claim 31 or 32, characterized in that the water present in the product has a water activity between 0.1 5 and 0.35.

34. The dry product according to claim 33, characterized in that the water present in the product has a water activity of between 0.25 and 0.3.

35. A dry product according to any of claims 31 to 34, characterized in that the product contains compounds that are capable of being eluted at different temperatures, the weight ratio fraction of the compounds eluted at a temperature between 1 50 ° C and 200 ° C to the fraction of compounds eluted at a temperature between 40 ° C and 100 ° C are greater than 0.3.

36. A dry product according to claim 35, characterized in that the fraction by weight ratio of the compounds eluted at a temperature of 1 50 ° C to 200 ° C to the fraction of compounds eluted at a temperature of between 40 ° C and 1 00 ° C is greater than 0.5.

37. A dry product according to claim 36, characterized in that the fraction by weight ratio of the compounds is added at a temperature between 1 50 ° C to 200 ° C to the fraction of compounds eluted at a temperature between 40 ° C and 100 ° C is greater than 0.6.

38. A dry product according to any of claims 31 to 37, characterized in that the product contains compounds that are capable of being eluted at different temperatures, the weight-relative fraction of the compounds eluted at a temperature of between 1 and 50. ° C at 200 ° C to the fraction of compounds the uids up to 200 ° C is greater than 0.25.

39. A dry product according to any of claims 31 to 38, characterized in that the product comprises cells adjacent to one side of the product, such cells define between them spaces, at least 50% of the spaces are not completely or completely sugar lenos.

40. A dry product according to any of claims 31 to 39, characterized in that the product comprises cells adjacent to one side of the product, such cells define spaces between them, at least 50% of these spaces contain a gaseous medium.

41 The dry product according to any of claims 31 to 40, characterized in that the product comprises cells adjacent to one side of the product, such cells define spaces between them, at least 50% of the volume of such spaces is filled to a regime of at least 50% with a gaseous medium.

42. The dry product according to any of claims 31 to 41, characterized in that the product is a vegetable or dried fruit.

43. The dry product according to any of claims 31 to 42, characterized in that the dried product is a dried fruit.

44. The product according to any of claims 31 to 43, characterized in that the product is a dry product.

45. The dry product according to claim 44, characterized in that the product comprises cells adjacent to one side of the product, such cells define spaces between them, at least 50% of these spaces contain a gaseous medium.

46. The dry product according to any of claims 31 to 45, characterized in that substantially all the cells of the dried product, which were not damaged before drying, remain substantially undamaged after drying.

47. A food composition having the improvement of containing a dry food product having a water content of between 4% and 7%, the dried product is a product in which at least 50% of the cells not adjacent to the face of the product still have a closed membrane, and the water present in the dried product has a water activity of less than 0.4.

48. The composition according to claim 47, characterized in that the food composition is useful as a sauce composition.

49. The process for dehydrating a product by pushing a gaseous drying medium to contact the product in a chamber, characterized in that the temperature and relative humidity of the drying medium are controlled so that the water elimination rate of the The product is such that it minimizes damage to the celular integrity of the product during the drying process.

50. The method according to claim 49, characterized in that the temperature and relative humidity of the drying medium is controlled so that the cellular integrity of at least 50% of the product cells not adjacent to one side of the product is maintained during the drying process.

51 The method according to claim 50, characterized in that the temperature and relative humidity of the drying medium is controlled so that the cell integrity of the product is substantially maintained during the drying process.

52. The method according to any of claims 49 to 51, characterized in that the water removal rate of the product is such that it minimizes damage to the structural integrity of the product during the drying process.

53. The process according to claims 49 to 52, characterized in that the structural integrity of at least 50% of the cells of the product not adjacent to one side of the product is maintained during the drying process.

54. The method according to claim 53, characterized in that the structural integrity of the product is substantially maintained during the drying process.

55. The method according to any of claims 49 to 54, characterized in that the relative humidity of the drying medium is controlled such that the difference between the relative humidity of the drying medium and the relative humidity of the product does not exceed a relative humidity of 70%.

56. The method according to claim 55, characterized in that the relative humidity of the drying medium is controlled so that the difference between the relative humidity of the drying medium and the relative humidity of the product does not exceed a relative humidity of the product. 60%

57. The method according to claim 56, characterized in that the relative humidity of the drying medium is controlled so that the difference between the relative humidity of the drying medium and the equilibrium relative humidity of the product does not exceed a relative humidity of 50. %.

58. The method according to any of claims 49 to 57, characterized in that the relative humidity of the drying medium in the chamber is increased to a maximum value that is within the range of 30% to 70%.

59. The method according to claim 58, characterized in that the maximum value of the relative humidity of the drying medium in the chamber is in the range of 50% to 70%.

60. The process according to claim 59, characterized in that the maximum value of the relative humidity of the drying medium in the chamber is in the range of 50% to 55%.

61 The method according to claim 58 or 59, characterized in that the value of the relative humidity of the drying medium reaches the maximum value, the relative humidity of the drying medium in the chamber remains substantially constant at the maximum value, or is allowed that only the relative humidity of the drying is gradually reduced, being supplied to the chamber substantially constant, until the relative humidity of the drying medium in the chamber begins to fall or begins to fall at an increased rate.

62. The method according to claim 61, characterized in that the relative humidity of the drying medium in the chamber is allowed to fall relatively quickly after the drop in the relative humidity of the drying medium has started or the rate of falling the relative humidity of the drying medium has begun to increase, until the water content of the product approaches the desired water content and the rate of evaporation of the product water becomes substantially independent of the drying medium.

63. The method according to claim 62, characterized in that the evaporation rate of the product water which becomes substantially independent of the drying medium, the relative humidity of the drying medium, is controlled to approach asymptotically at a predetermined value of relative humidity which provides the dried product to the desired water content.

64. The method according to claim 63, characterized in that the predetermined value of the relative humidity is less than the equilibrium relative humidity of the product corresponding to the desired water content, and the difference between the predetermined relative humidity of the drying medium. and the relative humidity of equilibrium of the product corresponding to the desired water content is in the range of 20% to 40% relative humidity.

65. The process according to claim 64, characterized in that the difference between the predetermined value of relative humidity and the equilibrium relative humidity of the product corresponding to the desired water content is in the range of 25% to 35% relative humidity .

66. The method according to claim 65, characterized in that the difference between the predetermined value of relative humidity and the equilibrium relative humidity of the product corresponding to the desired water content is approximately 30% relative humidity.

67. The method according to any of claims 63 to 66, characterized in that the relative humidity of the drying medium is maintained substantially at the predetermined value of relative humidity for a period in the range of 30 minutes to 1 20 minutes.

68. The process according to any of claims 49 to 67, characterized in that the drying medium is circulated through the chamber, so that the speed of the drying medium relative to the product is in the range of 1 M per second at 3 M per second.

69. The process according to claim 68, characterized in that the drying medium is circulated through the chamber, so that the speed of the drying medium in relation to the product is in the range of 1.5 M per second at 2.5 M per second.

70. The method according to claim 69, characterized in that the drying medium is circulated through the chamber, so that the speed of the drying medium in relation to the product is in the range of approximately 2 M per unit. second.

71 The process according to any of claims 61 to 70, characterized in that during the period while the relative humidity of the drying medium in the chamber is maintained substantially constant or gradually only decreases, the relative humidity of the drying medium in the chamber is not greater than 50%, the relative humidity less than the relative humidity of the product.

72. The process according to claim 71, characterized in that during the period while the relative humidity of the drying medium in the drying chamber is being maintained substantially constant or is only gradually reduced, the relative humidity of the drying medium in the chamber is not greater than 40% of the relative humidity less than the relative humidity of the product's equilibrium.

73. The method according to claim 72, characterized in that during the period while the relative humidity of the drying medium in the chamber is being maintained substantially constant or gradually increasing, the relative humidity of the drying medium in the chamber is not greater than 43% relative humidity and is less than the relative humidity of the product.

74. The method according to any of claims 62 to 73, characterized in that during the period while the relative humidity of the drying medium in the chamber is falling relatively rapidly, the relative humidity of the drying medium is controlled in a manner that the relative humidity of the drying medium in the chamber is not greater than 70% of the relative humidity less than the relative humidity of the product equilibrium.

75. The method according to claim 74, characterized in that during the period while the relative humidity of the drying medium in the chamber is falling relatively rapidly, the relative humidity of the drying medium is controlled so that the relative humidity of the drying medium is controlled. The drying medium in the chamber is not greater than 60% of the relative humidity less than the moisture content of the product.

76. The method according to claim 75, characterized in that during the period while the relative humidity of the drying medium in the chamber is falling relatively quickly, the relative humidity of the drying medium is controlled so that the relative humidity of the medium Drying in the chamber is not greater than 50% of the relative humidity less than the relative humidity of the product's equilibrium.

77. The process according to any of claims 61 to 76, characterized in that the drying medium is recirculated.

78. The process according to claim 58, characterized in that the relative humidity of the drying medium in the chamber is controlled by the introduction of a fresh dry medium, in the recirculation drying medium, at a rate in the lime drying medium. fresh that is introduced, does not exceed 21% by weight of the mass flow regime of the drying medium.

79. The process according to claim 78, characterized in that the rate at which the drying medium is fresh is introduced does not exceed 15% by weight of the mass flow rate of the drying medium.

80. The process according to claim 79, characterized in that the rate at which the drying medium is fresh is introduced does not exceed 10% by weight of the mass flow rate of the drying medium.

81 The process according to claim 80, characterized in that the rate at which the drying medium is fresh is introduced does not exceed 7% by weight of the mass fl ow rate of the drying medium.

82. The process according to claim 81, characterized in that the rate at which the drying medium is fresh is introduced does not exceed 4% by weight of the mass flow regime of the drying medium.

83. The process according to any of claims 61 to 82, characterized in that the fresh drying medium is introduced to a substantially constant regime of not more than 7% by weight of the mass fl ow rate of the drying medium during the period while the relative humidity of the drying medium in the chamber remains substantially constant at the maximum value of the relative humidity.

84. The process according to claim 83, characterized in that the fresh drying medium is introduced at a substantially constant rate of not more than 5% by weight of the mass flow rate of the drying medium during the period while the humidity The relative humidity of the drying medium in the chamber is being maintained substantially constant at the maximum value of the relative humidity.

85. The method according to claim 84, characterized in that the fresh drying medium is introduced at a substantially constant rate of not more than 4% by weight of the mass flow rate of the drying medium during the period while the humidity The relative humidity of the drying medium in the chamber is being maintained substantially constant at the maximum value of the relative humidity.

86. The process according to claim 85, characterized in that the fresh drying medium is introduced at a substantially constant rate of not more than 3% by weight of the mass flow rate of the drying medium during the period while the humidity The relative humidity of the drying medium in the chamber is being maintained substantially constant at the maximum value of the relative humidity.

87. The method according to claim 86, characterized in that the fresh drying medium is introduced at a substantially constant rate of no more than 2% by weight of the mass fl ow rate of the drying medium during the period while the relative humidity of the drying medium in the chamber is being kept substantially constant at the maximum value of the relative humidity.

88. The method according to claim 87, characterized in that the fresh drying medium is introduced to a substantially constant rate of not more than 1% by weight of the mass flow rate of the drying medium during the period while the relative humidity of the drying medium in the chamber is being maintained substantially constant at the maximum value of the relative humidity.

89. The method according to any of claims 62 to 88, characterized in that during the period while the relative humidity of the drying medium in the chamber is falling relatively fast, the fresh drying medium is introduced at a rate no greater than 21% by weight of the mass flow regime of the drying medium.

90. The method according to claim 89, characterized in that the rate at which the fresh drying medium is introduced increases from the beginning of the period to the end of the period during which the relative humidity of the drying medium in the chamber is falling relatively quickly.

91. The process according to any of claims 77 to 90, characterized in that no fresh drying medium is introduced to the recirculation drying medium, until the relative humidity of the drying medium has reached its maximum value.

92. The process according to any of claims 77 to 91, characterized in that during the period while the relative humidity of the drying medium in the chamber is approaching asymptotically to the predetermined value of the relative humidity, the fresh drying medium is introduced at a rate not greater than 5% by weight of the mass flow regime of the drying medium.

93. The method according to any of claims 77 to 92, characterized in that a fresh drying medium is introduced through an inlet opening and the outlet drying medium is expelled through an outlet opening, the size of the Inlet and outlet openings are controlled as a function of the nominal exposed surface area of the product according to a Modulation Index (Ml) in which it is defined as: Ml = Kp x NSP (Sen + Se?) / (Sen * Se?) Where Sen is the cross sectional area of the inlet opening to make the drying medium fresh, Sex is the cross sectional area of the outlet opening to expel the drying medium, and NSP is the nominal exposed surface area of the product, and Kp is a constant whose value depends on the product to be dried and the pressure / flow characteristics of the drying medium, and during the period while the relative humidity of the drying medium of the chamber is being maintained substantially constant to the maximum value, the value of the modulation index, lies on the scale of 1,000 to 1,000,000.

94. The process according to claim 93, characterized in that during the period while the relative humidity of the drying medium in the chamber is being maintained substantially constant at the maximum value, the value of the modulation index lies in the range of 2,000 to 8,000.

95. The method according to any of claims 49 to 94, characterized in that the temperature of the drying medium is controlled so that it is not at or above the degradation temperature, which could cause irreversible thermal damage to the product. product.

96. The process according to any of claims 49 to 95, characterized in that the temperature of the drying medium does not exceed 70 ° C.

97. The process according to any of the claim 96, characterized in that the drying medium is maintained at a temperature within the range of 40 ° C to 70 ° C.

98. The method according to any of claim 97, characterized in that the drying medium is maintained at a temperature within the range of 55 ° C to 65 ° C.

99. The method according to any of claims 49 to 98, characterized in that initially the temperature of the drying medium is increased to a maximum value.

100. The method according to claim 99, characterized in that by reaching its maximum, the temperature of the drying medium remains substantially constant thereafter.

1 01. The process according to any of claims 49 to 100, characterized in that the drying medium is ai re.

1 02. The process according to any of claims 49 to 101, characterized in that the drying medium is nitrogen.

103. The process according to any of claims 49 to 100, characterized in that the drying medium is air enriched with nitrogen.

104. The process for dehydrating a product by means of which a gaseous drying medium is heated and pushed to contact the product to be dried, characterized in that the temperature of the drying medium which is in contact with the product to be dehydrated is lower than the degradation temperature of the product, and the temperature of the product to be dehydrated is increased in a controlled manner during the drying process, the process comprises at least one step wherein the temperature of the drying medium is increased from a first temperature to a temperature adjacent to the maximum dehydration temperature, the increase in the temperature of the drying medium is such that during at least one step, there is a difference between the temperature of the product and the drying medium, the temperature difference is in the range of 0.1 ° C to 5 ° C.

105. The method according to claim 1 04, characterized in that the temperature difference between the product and the drying medium is less than 2.5 ° C. 1 06.

The method according to claim 1, characterized in that the temperature difference between the product and the drying medium is less than 1.5 ° C.

07. The process according to any of claims 1 to 10 to 10, characterized in that the temperature of the drying medium increases at a speed of less than 5 ° C per hour.

108. The process according to any one of claims 104 to 107, characterized in that the drying medium is initially maintained at the first temperature until the temperature inside the product is approximately at the first temperature.

109. The process according to claim 1 08, characterized in that the first temperature is approximately 40 ° C.

110. The method according to any of claims 104 to 109, characterized in that the rate of increase in the temperature of the drying medium is such that the temperature of the drying medium reaches the maximum degradation temperature at about the same time as the water content. desired product has been obtained.

111. The method according to any of claims 104 to 110, characterized in that the rate of increase of the temperature of the drying medium is substantially constant.

112. The method according to any of claims 104 to 112, characterized in that the maximum dehydration temperature is lower than the degradation temperature of the product.

113. The process according to any of claims 104 to 112, characterized in that the maximum dehydration temperature does not exceed 70 ° C.

114. The method according to claim 113, characterized in that the maximum dehydration temperature is in the range of 40 ° C to 50 ° C.

115. The process according to any of claims 104 to 114, characterized in that the product is dried at a water content of less than 20%.

116. The process according to claim 115, characterized in that the product is dried at a water content of about 10%.

117. The method according to any of claims 104 to 116, characterized in that the drying medium is recirculated.

118. The process according to claim 117, characterized in that during the end of the dehydration process, less than 4% by volume of the fresh drying medium is added to the drying medium.

The process according to any of claims 104 to 18, characterized in that towards the end of the dehydration process not more than 1% of the moisture of the recirculated drying medium is condensed from the drying medium to as it is being recirculated.

The process according to any of claims 104 to 1 19, characterized in that the product is dried at a water content below about 10%, and the relative humidity of the drying medium during the period while The water content of the product is being reduced below 20%, it lies in the range between 10% and 20%.

121. The process according to any of claims 104 to 1 20, characterized in that the product is dried at a water content of less than 7%.

122. The dried product, dried by the dehydration process according to any of claims 49 to 1 21. SUMMARY A dry fruit or vegetable has a water content in the range of 4% to 7%, and has a water activity of 0.4. Substantially, all the cells of the dried product are not damaged. An air drying process is moderate and comprises four phases, during which the temperature of the drying air is maintained at 60 ° C. In the first phase, the relative humidity of the drying air is allowed to be between 50% and 55%, and it remains substantially constant at this level during the second phase, keeping the air of drying with the fresh air substantially constant In a third stage of the process, the relative humidity of the drying medium is allowed to relatively reduce rapidly until the fourth phase begins, at such a stage, the relative humidity is allowed to approach asymptotically at a predetermined relative humidity value . During the drying process, excessive temperature differences and relative humidity differences between temperature and relative humidity, respectively of the drying medium and the product, are avoided in order to minimize damage to the structure. cellular product.