ES2212922A1 - Method for making a citrus fruit extract rich in pectin - Google Patents

Abstract

The invention concerns a method for continuous production of citrus fruit extracts rich in soluble pectins, which consists in: eliminating the outer part of the peel consisting of the zest heating the core citrus at a temperature less than 110 DEG C subjecting in less than three seconds, the heated citrus fruit to a reduced pressure finally, treating the resulting product so as to produce an extract more or less rich in pulp.

Description

Procedure for the preparation of extracts of citrus

The present invention relates to a procedure for the preparation of citrus extracts rich in pectin. It also refers to susceptible extracts if obtained by said procedure. The invention extends also to the drinks that incorporate the extract.

In the continuation of the description and in the claims, the term "citrus" designates in particular but not limitatively, fruits of the orange type, lemons, Grapefruits

The document FR-A-2 731 588 describes a composition to stabilize fruit-based drinks, in Particularly the orange juice. Indeed, the latter contains a certain amount of pulp that has a tendency to settle in the course of time, making a composition called "unstable". It is the reason why it is necessary to give the juice all its aroma as well as to uniformize its appearance, stir the fruit juice before of its consumption The proposed stabilizing agent consists of a composition based on pectins and alginates that is added to the orange aroma during the preparation of the drink allowing thus the maintenance of the pulp in suspension. This solution therefore has the disadvantage of requiring an agent external stabilizer of unnatural origin, which must be added extemporaneously during the preparation of the drink.

WO 99/47008 tends to resolve the problem of the origin of the stabilizing agent. Part in principle of the finding that the citrus skin is very concentrated in pectins. It has also been indicated that pectins they have stabilizing properties of solid particles. Consequently, this document describes a procedure according to the which a mixture of parts of citrus and in particular of skin, of juice and bone, is subjected to an aqueous extraction that leads to obtaining an aqueous extract containing particles solid. The extract is then separated from its particles thick so that you get a liquor that includes up to  15%, preferably between 1 and 5% of pulp by weight. The liquor is a then subjected to the action of a pectolytic enzyme that allows to decrease the molecular weight of the pectins present in the liquor to make them soluble and surfactants. Proceed to continuation to a pasteurization stage and after centrifugation One of the drawbacks of this procedure is that the aqueous extraction does not directly solubilize the pectins so that it is necessary to proceed to a treatment subsequent enzyme.

In addition, the presence of skin in the procedure leads to obtain extracts that contain terpenes that give the product a "burning" flavor and color off.

The document FR-A-2 782 899 describes a discontinuous process of thermomechanical treatment of the fruit whole or of your skin that consists essentially of applying to high temperature material, whose value is not specified, coupled to high pressure, followed by a sharp expansion instantaneous towards reduced pressure. This document indicates also that the skin recovered after treatment suffers from then a classic pectin extraction treatment what confirming that, according to this document, all skin is removed (flavedo + albedo). This procedure therefore presents the inconvenience of leading to an extract poor in soluble pectins (if the skin is removed) or rich in terpenes (if the fruit remains whole).

The problem that is proposed to solve the invention It is therefore to develop a procedure for the preparation of citrus extracts that allow pectins to be extracted directly soluble, and this, in significant quantities, and obtain an extract free of terpenes whose drawback is to confer a burning flavor and a color off to the final product.

Another problem that has been proposed to solve the invention is to develop a process for the preparation of extracts, whose pulp content may vary up to about high contents, of the order of 1 to 2.5% by weight.

For this, the invention proposes a procedure for the continuous preparation of citrus extracts rich in soluble pectins, according to which:

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 It is eliminated the outer part of the skin constituted by the flavedo;

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 heats up the citrus thoroughly at a temperature below 110 ° C;

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 submits, in less than 3 seconds, the citrus heated to a pressure reduced;

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 Finally, the product obtained is treated in a way that leads to an extract more or less rich in pulp.

The applicants have in fact found that totally surprising way, the fact of applying a pressure reduced in a time less than 3 seconds to a whole citrus heated, allowed to degrade the cell walls of the albedo of the Citrus skin and concomitantly extract the pectins soluble nonvolatile present in said albedo, in amounts important. As I recall, citrus skin comprises two different parts. The external part called "flavedo" It contains most of the essential oils and aromas volatile while the internal part, called "albedo", It essentially contains soluble pectins. In other terms, not only the pectins present in the final extract are extracted directly without needing complementary stages and are 100% natural, but also, its significant proportion allows improve the long-term stability of the extract and this even for significant quantities of pulp. On the other hand, the procedure of the invention has the advantage of being performed on whole citrus fruits, that is, citrus fruits that have not suffered any physical deterioration and oxidation.

The heating combination, the citrus temperature in the core advantageously included between 60 and 90 ° C, preferably equal to 80 ° C, with a low setting reduced pressure, preferably less than 0.075 bar absolute, in less than 3 seconds, advantageously in less than one second, it leads to the following phenomena. The sudden low setting vacuum causes instantaneous evaporation of the constitution water of citrus, which causes a total or partial degradation of citrus tissues due to the creation of microchannels intercellular, which favor the extraction of compounds dyes and polysaccharides, in particular pectins. The same also causes an inhibition of endogenous enzymes due to bleaching of fruits, which allows to avoid the phenomena of enzymatic darkening The combination of heat and setting under sudden reduced pressure, it also leads to pre-crushing due to the instant evaporation of a part of the water from Constitution. Finally, placing under reduced pressure causes a  immediate cooling of the plant material due to a sharp return to thermodynamic equilibrium, in practice from 90 ° C to approximately 40 ° C. If the rapid passage under reduced pressure it constitutes one of the essential elements of the procedure, said pressure can be maintained for a variable time, in the practice between 3 and 4 seconds.

In addition, the preliminary stage of the elimination of flavedo, in practice by scratching or peeling allows to free yourself from the presence of pesticides that exist on the surface of the fruits, as well as terpenes that give the extract obtained a burning sensation when ingestion takes place.  However, to the extent that almost all of the albedo remains present on the surface of the fruit, the extraction of soluble pectins, allowing to obtain a stable extract

In an advantageous embodiment, the water of evaporated constitution when sudden low setting occurs reduced pressure is condensed, for example by means of a surface exchanger, and then recovered in the form of water aromatic This aromatic water, which represents approximately 8% of The mass of the product contains different families of compounds, in particular numerous terpenic hydrocarbons that is necessary remove. The aromatic water is therefore subjected to various purification treatments, for example to a distillation of column fraction. The aromatic water then treated can be introduced again eventually in the final extract.

As already said, the product obtained at end of heating stages and after low setting sudden reduced pressure, is then treated according to the desired pulp content in the final extract. The pulp is constituted by the cell walls out of the degradation of the albedo when put under sudden reduced pressure Citrus This pulp can enter the extract composition final in variable contents, depending on the mode of separation of said pulp.

Thus, in a first embodiment, to get a citrus extract that looks like a juice that is very poor in pulp, the treatment consists of a Pressing, eventually performed at atmospheric pressure. Without However, the pulp content of the extract may vary depending on Pressing mode. In practice, citrus juices obtained at the end of the process of the invention comprise a very low pulp content, less than 0.2% by weight.

In a second embodiment, to obtain a citrus extract rich in pulp, which presents the consistency of a mash named below "pectical mash", the Treatment consists of a refined. For the term "refined", an operation that involves passing the product obtained is designated through a grid or equivalent whose mesh size allows the passage of a greater or lesser part of the pulp. Advantageously, the refining is carried out under vacuum so that the oxygen content in the refined product. In practice, the citrus puree obtained at the end of the process of the invention Contains between 1 and 2.5% of pulp by weight of wet matter treated.

As already stated, one of the interests of the procedure is to get the pectins directly extracted soluble and this in large quantities in practice between 0.3 and 2.5% by weight of the treated wet matter. The appliers have found that the soluble pectin content in the extract Final was important in mash and juice. In practice, the juice obtained by pressing contains between 0.3 and 1.8% pectins soluble in weight of the treated wet matter. Also, mash obtained by refining contains between 0.5 and 2.5% pectins soluble in weight of the treated wet matter.

The content of soluble pectins (P.S.) and of cell walls (P.C.) or pulp in purees, it is variable according to the fruits: well, for the lemon, P.S. It is close to 2% and P.C. it is close to 2%; for oranges Valencia, P.S. is close to 1% and P.C. close to 2.5%; for grapefruits, P.S. It is close to 0.5% and P.C. close to 1%, the proportions indicated with respect to wet weight of the treated product and for thorough heating of the fruit at 80 ° C, before putting under sudden reduced pressure.

The invention also relates to beverages that incorporate extracts that can be obtained at the end of procedure in the form of juices or purees. These drinks result of the addition of water and sweeteners to extracts obtained.

When the removal of the flavedo is carried out by scratching, the scratching operation causes in practice the removal of a small part of the albedo.

In an advantageous embodiment, the mixture flavedo-albedo that comes from scratching can be treated separately to recover water from it aromatic after distillation purification, absorption, decantation, so that some compounds are selected volatile aromatics These aromatic fractions can be introduced completely or partially in the juices or purees obtained at the end of the process of the invention.

A part of the essential oils contained in the flavedo will be recovered with the aromatic waters (oleic phase higher). A part of these compounds after purification may be introduced again in the product. Depending on the type of citrus (lemon, orange, grapefruit), the treatment by rise of temperature and setting in rapid depression allows to obtain some yields in essential oils ranging from 1.7 to 2.5 liters per ton of whole fruits. These oils have some classical compositions and have in this sense a very content high limonene (more than 95% in essential oils of grapefruits).

As already said, the set of Treatments of the invention are carried out continuously. In the practice, the procedure can be performed in an installation of the same type as described in the document EP-A-727 948 incorporated here as reference.

The invention also relates to the extract of citrus fruits that can be obtained by the procedure previously described.

It also aims at a mash of citrus that comprises between 0.5 and 2.5% soluble pectins and between 1 and 2.5% of pulp by weight of the treated wet matter.

The invention finally relates to a juice of citric fruit comprising between 0.3 and 1.8% of soluble pectins by weight of the treated wet matter.

The invention and the advantages that result from it will stand out better from the following embodiment example with the support of the attached figures.

Figure 1 is a diagram representing the different stages of the process of the invention.

Figure 2 is a comparative table of the physicochemical characteristics of the purees of the invention and of Traditional juices

Figure 3 is a comparative table of the biochemical characteristics of the purees of the invention and of the traditional juices

\hbox{47 g.}

The lemons used in this example are of the Portofiori variety (Spain), the Valencia variety oranges (Spain) and the Cavendish grapefruits (Israel). They have mean masses respectively equal to 158 ± 23 g .; 181 ± 31 g. and 379 ±

 \ hbox {47 g.} 

As presented in the diagram in the figure 1, these treated citrus fruits have suffered, in a first stage, a partial peeling using a fruit scraper (Polycitrus type of INDELICATE). This treatment allows the flavedo to be removed as well. as a part of the albedo. This results in the elimination of most essential oils, pesticides and fungicides contained in the flavedo as well as a part of the compounds contained in the albedo. This treatment causes a total loss in mass of the fruit that varies from 0.5% for Grapefruits at 5% for lemons (2% for oranges). The aromatic compounds contained in the flavedo (mostly essential oils and terpenic compounds) may be recovered by distillation and fractionated in column to be introduced back into juices or purees before final conditioning.

In a second stage, the whole fruits scratched They are treated by sudden reduced pressure. Plus precisely, they are introduced into a stoving chamber where they are heated to 80 ° C thoroughly and then suddenly introduced (pneumatic valve opening time less than 1 second) in an expansion chamber where a high vacuum is lower than 0.075 bar absolute.

Vaporized constitution waters are, by use of a surface exchanger, condensed and then recovered in the form of aromatic waters (10% approximately mass of the product). These aromatic fractions they contain different families of compounds with in particular numerous terpenic hydrocarbons. They may be recovered by distillation and fractionated in column.

Products out of pressure Sudden reduced may suffer 2 different technological pathways. The first way it uses a product press to reduce the final pulp content and get some pectic juices from citrus The second solution is to refine these products (PH3 / Auriol type refiner equipped with a cylindrical grid (drilling 1 millimeter in diameter)) and in obtaining some purees citrus pectics (very rich in pulp). This refining is done under vacuum in order to decrease the final oxygen content in the refined products The first and second stages of the procedure induce a first reduction of oxygen content (the product obtained at the end of the two stages has an oxygen content of  approximately 30%) due to the effect of high vacuum and refining under vacuum causes a decrease in oxygen content until approximately 5% This low oxygen content limits the oxidation phenomena and therefore obscuration not enzymatic

A juices or purees can then add water and sugar in order to obtain drinks with viscosity lower due to pulp contents (wall fragments cellular) and lower pectins. Drinks, juices or purees are finally homogenized, pasteurized and then conditioned.

The use of refining to obtain some purees allow to obtain extraction yields higher than those traditionally obtained by classical procedures to juice preparation by pressing the juice vesicles, without incorporation of citrus skin, of the type developed by FMC Corporation.

Thus, the treatment of lemons according to the diagram in figure 1 allows to obtain a yield of final extraction of mash (i.e. after scratching, heating, put under brutal and refined reduced pressure) of 61% The average juice yield obtained by a procedure Traditional is approximately 35% (with values that vary from 27 to 43% depending on the size and variety of lemons). The lemon peel puree yield obtained by this new procedure is therefore almost 2 times higher than that of traditional extraction procedures.

The treatment of oranges for this new procedure allows to obtain a yield of 60%. The utilization in the industry of traditional procedures allows, according to the size of the oranges and the procedure used, get 50% yields approximately.

Finally, referring to grapefruits, it is reached 60% yield while traditional procedures allow to obtain yields that vary from 45 to 55% according to the Grapefruit size and the procedure used.

This increase in performance in all three cases is due to the incorporation of a part of the fruit albedo in the juice. The albedo is degraded when the treatment takes place sudden reduced pressure setting; this is incorporated into the juice when product refining takes place.

The physicochemical characteristics of purees obtained by the set of treatments: partial peeling, put under sudden reduced pressure, refined (see figure 1) as well such as juices obtained by using a procedure Traditional are represented in figure 2.

The lemon puree, obtained by the treatments designated in Figure 1, has a pH of 2.85 and acidity Titular of 53.6 mEq. for 100 g of product. By comparison a Traditional lemon juice has a pH of 2.50 and acidity Titrable of 84.0 mEq for 100 g of product.

The orange puree, obtained by these treatments (figure 1), have a pH of 3.60 and acidity Titrable of 15.8 mEq for 100 g of product. By comparison, a Traditional orange juice has a pH of 3.54 and acidity Titrable of 17.0 mEq for 100 g of product. Also, mash Grapefruit, obtained by these treatments (Figure 1), has a pH of 3.65 and a titratable acidity of 13.1 mEq for 100 g of product. By comparison a traditional grapefruit juice has a pH of 3.25 and a Titratable acidity of 13.0 mEq for 100 g of product.

The lowest acidity of the purees obtained as described above in figure 1 with respect to some juices traditionally obtained is due to the addition of albedo in the products when the stages of depression take place Fast and refined. Citrus albedo has a pH that varies from 4 to 4.5 and a low titratable acidity (due to a low organic acid content in albedo) compared to values obtained in the juices contained in the segments.

The color study carried out using a Chromometer (Minolta, CR-A70) in mode (L, a, b) about the different products is represented in the table of the Figure 2. The intensity of clarity of the products follows the value Increase of parameter L and intensity of yellow color (particularly sought in citrus juices and purees) follow the increasing value of parameter b.

Lemon, orange and grapefruit purees obtained by the procedure described in figure 1 has about values of L respectively equal to 59.6; 58.8; 44.9 while that lemon, orange and grapefruit juices have values of L respectively equal to 40.9; 49.0; 34.1. The purees of Citrus fruits therefore have a lighter color compared to that of Traditional juices

Lemon, orange and grapefruit purees have values of b respectively equal to 10.5; 40.7; 20.5 while lemon, orange and grapefruit juices have about values of b respectively equal to 2.3; 24.6; 2.5 The purees of Citrus fruits are characterized because they have a more yellow color intense.

In the end, the colors of the lemon purees, from Orange and grapefruit are characterized by a light color and a intense yellow

Dry matter of purees and juices have been determined by gravimetry and dry extracts soluble by refractometry (refractometer 0-32 ° Brix).

Lemon, orange and grapefruit purees have percentages of dry matter with respect to wet matter respectively equal to 11.6; 13.1 and 12.6% (see figure 2) while traditional juices have percentages of dry matter clearly lower (respectively 8.5; 7.0 and 9.6%). These values are clearly higher in purees treated as indicated in figure 1 are attributed to a higher content of cell wall fragments (pulp). The treatment by setting under sudden reduced pressure and the refined are so concomitant responsible for this net increase in dry matter: a part of the albedo (particularly rich in cell walls) has been  incorporated into the product when these two take place stages

Also, lemon, orange and orange purees Grapefruit have some percentages of soluble dry extract with with respect to wet matter respectively equal to 10.0; 10.1 and 11.0% while traditional juices have percentages of dry extract soluble clearly lower (respectively 7.4; 6.1 and 9.1%). These very clearly higher values in purees are due to a high value of the dried extract soluble in the albedo (high content of sugars and soluble pectins) of which a part It is incorporated into the product when the treatments of heating / setting under reduced and refining pressure.

The finished products have their consistency, viscosity and pulp content, rheological characteristics of a mash described to continuation.

The viscosities of the purees have been determined by the use of a Haake viscometer (model 550) provided with an MV-DIN module.

These 3 products have a behavior reofluidifying and are not thixotropic. Apparent viscosity measured at constant speed (100 rad.s -1) varies from 21 Pa.s for the lemon puree at 260 mPa.s for the grapefruit puree (820 mPa.s for orange puree). By comparison, some are obtained values below 2.5 mPa.s in the case of citrus juices obtained by a traditional procedure.

These three major viscosity differences are mainly attributed to the very high contents of walls cell and soluble pectins in the purees obtained by this New procedure.

The flow threshold of these purees follows the same classification with values respectively equal to 70, 15 and 7 Pascals for lemon, orange and grapefruit purees. These threshold values are according to the nature of the mash comparable to those obtained for example for a chocolate paste (\ sim15 Pascals) or a tomato puree (~ 30 Pascals).

The consistency of these purees determined using a Bostwick consistometer is proportional to the distance traveled by the mash under the effect of its own weight (100 g) in 30 seconds on a horizontal surface. The most consistent puree is the one that comes from the lemon ( d = 2 cm) while the one that comes from the orange and the grapefruit are slightly more fluid (respectively d = 5.5 cm and d = 9 cm). The consistency of the juices obtained in the traditional way has not been measured: these juices have no consistency due to their low content of fragments of cell walls and soluble pectins.

The absence of essential oil in purees endings can be doubly justified:

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most the essential oils contained in the citrus flavedo (live yellow part rich in glands with essential oils) has been partially withdrawn when the step on the fruit scraper (type Sfumatrice, Polycitrus or Citrorap),

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the oils essentials still present after partial scratching of the flavedo are vaporized when the sudden passage under reduced pressure takes place and They are therefore recovered in aromatic waters. This stage allows not only a destructuring of plant material but also a total elimination of essential oils contents still in the flavedo.

The results referring to the contents of MIA, soluble pectins as well as their acid contents galacturonic are represented in the table of figure 3.

The contents of cell wall fragments and soluble pectins of these products have been determined by the 80% ethanol precipitation procedure (M.I.A .: Alcohol Insoluble Material).

The M.I.A. mainly constituted by parietal fragments and soluble pectins are present in very high proportions in the purees from the treatments Figure 1 with increasing values of 1.6% (with respect to the wet matter) in grapefruit puree, 3.4% in orange puree and 3.8% in the lemon puree. The average acid percentages galacturonic that translate the purity of these components Polysaccharides are equal to approximately 30%.

Conversely, traditional juices have some low contents of alcohol insoluble material with values in the 3 juices below 0.6%. In addition, the purity of these polysaccharides in galacturonic acid is low with values that They are around 10% in the 3 traditional juices.

The sudden pressure treatment reduced therefore allows to obtain much richer products in cell wall fragments with more content important of pectic polysaccharides.

The contents of soluble pectins in the Insoluble materials in alcohol (M.I.A.) obtained from Citrus purees have been determined under two conditions of different extraction: in weakly acidic medium at temperature ambient (pH 4; 20 ° C) and in strongly hot acid medium (pH 1.5; 90 ° C). These contents are respectively equal to 0.77; 0.41 and 0.23% for lemon, orange and grapefruit purees in the case of extraction at pH 4, 20 ° C. In the case of an extraction stronger (pH 1.5, 90 ° C), soluble pectin contents are logically, clearly superior with content respectively equal to 1.84; 1.06 and 0.56% in lemon purees, of orange and grapefruit. The galacturonic acid contents of These pectins are between 50 and 70%.

The contents of cell wall fragments are determined after extraction at pH 4, 90 ° C considering that all of the soluble pectins has then been extracted. These contents are logically lower in the case of MINE. of grapefruit (1.04%) and are respectively equal to 1.96 and 2.33% in the cases of the M.I.A. of lemon and orange puree.

The contents of soluble pectins have not been determined in traditional juices because of the quantities too low pectins that would have been obtained (less than 0.1% in the 3 traditional juices).

The high contents of M.I.A. and pectins soluble in citrus purees obtained from treatments depicted in figure 1 are directly correlated with the high viscosity and high consistency of these purees.

Regarding the pectic juices obtained by pressed after the low pressure stage Sudden, cell wall contents are very low and vary depending on the type of pressing. The contents of pectins soluble are on the contrary close to those of the purees and vary from 0.5% for grapefruit pectic juice to 1.5% for pectic juice of lemon (case of extraction at pH 1.5; 90 ° C).

Tests carried out by an analysis jury expert indicate the organoleptic characteristics of these 3 purees:

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the colors of purees are nice, clear with intense vivid yellow colors particularly in orange and grapefruit purees;

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the taste in the 3 products is similar to a traditionally pressed juice but with a slightly less marked freshness;

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Not observed no note of cooking, revealing of a warming too intense, denaturing aromatic characteristics initials;

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heartburn in particular in lemon and grapefruit purees it is very nice and not aggressive contrary to that of the juice obtained traditional;

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the products no they provide no heat in the mouth which confirms the total absence of essential oils in the final purees;

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the products they have a slight bitterness (more marked in the case of grapefruit) due to the extraction of albedo from fruits when it takes place the procedure for preparation that can easily be attenuated by increased sugar content of products.

These new products thus presented are intended to be marketed as food products intermediates and can therefore be used as an additive of preparation.

The different fields of application are the following:

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purees used in dairy products, baby food or cake shop;

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nectar type drinks obtained after dilution of the purees (see figure 1): a 1/3 dilution with water with the same grade Brix provides according to the expert jury the best compromise regarding viscosity, the aromatic intensity, bitterness and acidity in the mouth.

The new products obtained use three Consecutive fruit treatment devices that can be adapted to industrial productions by a simple dimensioning of its components. In effect, these three technologies: fruit scraper (type Polycitrus brand INDELICATO), put under sudden reduced pressure, refined (type PH3 / Auriol or low refiner) empty) can be or are automated so that they work in continuous and to optimize the energy balance.

Claims (8)

1. Procedure for the preparation of citrus extracts in continuous, characterized in that:

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It is eliminated the outer part of the skin constituted by the flavedo;

?

heats up the citrus thoroughly at a temperature below 110 ° C;

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submits, in less than 3 seconds, the citrus heated to a lower pressure at 0.075 bar absolute; Y

?

Finally, the product obtained is treated or by pressing to obtain a juice, or by refining to obtain a puree.

2. The method according to claim 1, characterized in that the juice obtained at the end of the pressing stage contains less than 0.2% of the pulp by weight of the treated wet matter. 3. Method according to claim 1, characterized in that the mash obtained at the end of the refining step contains between 1 and 2.5% of pulp by weight of the treated wet matter. 4. Method according to claim 3, characterized in that the refining is carried out under vacuum. 5. Method according to claim 1, characterized in that the juice obtained by pressing contains between 0.3 and 1.8% of soluble pectins by weight of the treated wet matter. Method according to claim 1, characterized in that the puree obtained by refining contains between 0.5 and 2.5% of soluble pectins by weight of the treated wet matter. 7. Method according to claim 1, characterized in that the removal of the flavedo is obtained by scratching or peeling the citrus. Method according to claim 7, characterized in that the flavedo is treated separately to recover essential oils therefrom.