CA1253028A - Process for preserving fresh fruit and vegetables - Google Patents
Process for preserving fresh fruit and vegetablesInfo
- Publication number
- CA1253028A CA1253028A CA000491661A CA491661A CA1253028A CA 1253028 A CA1253028 A CA 1253028A CA 000491661 A CA000491661 A CA 000491661A CA 491661 A CA491661 A CA 491661A CA 1253028 A CA1253028 A CA 1253028A
- Authority
- CA
- Canada
- Prior art keywords
- product
- fruit
- temperature
- vegetable
- flavour
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B7/00—Preservation or chemical ripening of fruit or vegetables
- A23B7/14—Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10
- A23B7/144—Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10 in the form of gases, e.g. fumigation; Compositions or apparatus therefor
- A23B7/148—Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10 in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B7/00—Preservation or chemical ripening of fruit or vegetables
- A23B7/005—Preserving by heating
- A23B7/01—Preserving by heating by irradiation or electric treatment
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B7/00—Preservation or chemical ripening of fruit or vegetables
- A23B7/015—Preserving by irradiation or electric treatment without heating effect
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B9/00—Preservation of edible seeds, e.g. cereals
- A23B9/02—Preserving by heating
- A23B9/04—Preserving by heating by irradiation or electric treatment
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B9/00—Preservation of edible seeds, e.g. cereals
- A23B9/06—Preserving by irradiation or electric treatment without heating effect
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B9/00—Preservation of edible seeds, e.g. cereals
- A23B9/16—Preserving with chemicals
- A23B9/18—Preserving with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor
- A23B9/20—Preserving with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
- B65B25/00—Packaging other articles presenting special problems
- B65B25/02—Packaging agricultural or horticultural products
- B65B25/04—Packaging fruit or vegetables
- B65B25/041—Packaging fruit or vegetables combined with their conservation
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Wood Science & Technology (AREA)
- Zoology (AREA)
- Food Science & Technology (AREA)
- Polymers & Plastics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Agronomy & Crop Science (AREA)
- Mechanical Engineering (AREA)
- Storage Of Fruits Or Vegetables (AREA)
Abstract
ABSTRACT
A process for preserving fresh fruit/vegetable products comprises the steps of; heating the fruit/vegetable product rapidly and uniformly to a temperature sufficient to destroy the natural enzymes which are present in the product without cooking the product, and immediately thereafter, cooling said product rapidly to a cold condition to remove the enzyme destroying heat before any significant cooking of the product can occur and to cool the product to a temperature which will inhibit deterioration of the freshness thereof. Shortly thereafter, while the product remains in said cold condition, it is placed in a sealed gas-type package. Shortly thereafter the packaged product is irradiated to an extent sufficient to sterilize the product and prevent the formation of degenerative gas in the product, without damaging the product to thereby provide an enzyme-free, sterile and hermatically packaged fruit/vegetable product which has its fresh flavour and texture characteristics substantially unaltered and which can be stored without deterioration of freshness, flavour or texture for a long time.
A process for preserving fresh fruit/vegetable products comprises the steps of; heating the fruit/vegetable product rapidly and uniformly to a temperature sufficient to destroy the natural enzymes which are present in the product without cooking the product, and immediately thereafter, cooling said product rapidly to a cold condition to remove the enzyme destroying heat before any significant cooking of the product can occur and to cool the product to a temperature which will inhibit deterioration of the freshness thereof. Shortly thereafter, while the product remains in said cold condition, it is placed in a sealed gas-type package. Shortly thereafter the packaged product is irradiated to an extent sufficient to sterilize the product and prevent the formation of degenerative gas in the product, without damaging the product to thereby provide an enzyme-free, sterile and hermatically packaged fruit/vegetable product which has its fresh flavour and texture characteristics substantially unaltered and which can be stored without deterioration of freshness, flavour or texture for a long time.
Description
Field of Invention This invention re]ates to the preservation of fresh fruit and veqetables. In particular, this invention relates ~o an improved process Eor prolonginq the storaqe life of fre~sh fruit and veqetables at ambient storage temperatures without deterioration of freshness, 1avour and texture..
Background of _v ntion Despite the fact that fresh Eruit and veqetables have been preserved by many methods, the systems which have been developed to date all tend to result in a loss of ~reshness durin~ processing or a loss of freshness aEter a short period of storage. In addition, the texture and ~lavour of the fruits and vegetables which are preserved by present methods is also signiEicantly changed.
It is well known to reErigerate or freeze fruit and vegetables in an attempt to prolong storage liee of these products.
It is also well known to use hermatic seal film, bags, packages or containers, with our without inert gases, to increase the storage life of Eresh Eruit and vegetables. In addition, attempts have heen made to increase storage life by subjecting the Eruits and veqetables to irradiation. While each of these techniques provides an improvment over the mere storing of the fruits and vegetables at ambient temperature, the systems have serious limitations whether used individually or in combination.
Some fruits such as papaya and manqo and the like cannot be frozen without destroying the texture and flavour. Furthermore, without the deactivation of enzymes, ethylene qas is produced and the flavour and texture of the products deteriorates rapidly, even ~53028 when refrigerated. Radapperation has proven to be the most effective long range chemical free way of preservin~ food such as fruit and vegetables. In this proces.s, the fruits and vegetables are cooked and are then placed in a hermatic sealed container which is then sterilized by an irradiation process. This process is not suitable for ~resh fruit or vegetable preservation because the texture of the flavour is destroyed.
Enzymes are a qroup of proteins found in living plant cells which catalyze a variety of chemical reactions. Over one thousand such enzymes have been discovered in fruits and vegetables~ When fruits and vegetables are harvested, it is normal for senescence to set in. During this period ethylene ~as is formed within the fruit or vegetables. This gas triggers the activation of the enzymes, e.~. breakdown of pectin, protein, etc., which causes a breakdown of the fruit or vegetables.
Enzymes are deactivated by heat to coa~ulate or denature at temperatures over 50C.
The freshness, texture and flavour of many fruits and vegetables will be adversely affected if the fruit or vegetable is held at the enzyme deactivating temperature beyond a critical dwell time which varies with different fruits or ve~etables. Generally, if a fruit or vegetable is heated to a temperature of 90C and is held at this temperature for ten minutes, the naturally occurring enzymes will be deactivated.
It is known that fruits and ve~etables can be damaged if subjected to excessive irradation and consequently it is desirable to minimize the radiation dosa~e used for the purpose of sterilizing ~53028 fruits and vegetables.
Research and reports from medical authorities .show that many people are allergic to sulphur dioxide. Sickness and death have resulted from consumption of sulphur dioxide. Sul~hur dioxide is used in fruit and vegetable salads, dried fruits, etc. to retain freshness, colour and to partially preserve.
The present process allows cut fruits and vegetables, e.g.
fresh fruit salad and fresh vegetable salad to be prepared, hold and eaten without the need to use sulphur dioxide as a preservative.
Summary of Invention It is an object of the present invention to provide a process which will substantially increase the storage life of fresh fruits and vegetables without destroyinq their freshness, texture or flavour.
Accordinq to one aspect of the present invention, a process for preserving the freshness, flavour and texture of fresh fruits or veqetable products comprisinq the steps of heating the fruit or vegetable product rapidly and uniformly by means of a microwave heatinq system to a temperature and retaining the product at the enzyme deactivating temperature for a dwell time sufficient to deactivate all of the natural enzymes which are present in the product without cooking the product, and immediately thereafter, cooling said ~roduct rapidly to a sufficient extent to remove the enzyme deactivating heat before any cooking of the product can occur, and to cool the product to a temperature which will inhibit deterioration of the freshness, flavour and texture thereof and ~2530Z8 shortly thereafter, while the product remains in said cold condition, packa~ing and hermetically sealing the cooled product in a container which contains an inert gas, irradiating the packaged product, using a food sterilizing form of radiation to an extent sufficient to sterilize the product and prevent the formation of degenerative qas in the product, without damaqing the product to thereby provide an enzyme-free, sterile and hermetically packagea fruit or vegetable product which has its fresh flavour and texture characteristics substantially unaltered and which can be stored without deterioration of freshness, flavour or texture for a long time.
The invention will be more clearly understood after reference to the following detailed specification read in conjunction with the drawinqs wherein:
Figure 1 is a diagram illustrating the various steps of the process of the present invention.
Fruits and vegetables which can be processed by the present invention include: apples, oranges, grapefruit, lemon, grapes, peaches, nectarines, olives, cherries, elderberries, avocado, mango, gooseberries, strawberries, raspberries, boysenberries, youngherries, bana~as, tomatoes, guava, pineapple, soursop, jackfruit, broccoli, cauliflower, carrots, peas, potatoes, french fries, oka, beets, onions and peppers.
Various other fresh fruit and vegetables are capable of beinq processed hy the present invention and the above list is intended to be representative rather than limiting.
;3028 Refore a particular type of fruit or vegetable is processed it is necessary to carry out some preliminery enzymic testing to determine~ its optimum enzyme deactivating dwell time. The optimum enzyme deactivatinq dwell time is the maximum time for which a particular type of fruit or vegetable may be maintained at the enzyme deactivating temperature without adversely affecting its freshness, texture and flavour. The temperature of the product should be controlled by suitable sensor devices to maintain the product at an even temperature. Samples of the particular fruit or vegetable which is to be processed should be heated to the required enzime deactivating temperature and held at this temperature for various time periods and then subjected to laboratory and taste tests to determine an appropriate dwell time. Periodic tests should also be carried out during production runs to ensure the the dwell time is correct. It is desirable to maximize the enzyme deactivating dwell time to thereby permit the sterilizing irradiation dosage to be minimized. If the product is overheated it will soften or rupture the cell walls of teh product and give the product a cooked flavour and texture.
As illustrated in Fiqure 1 of the drawings, the fruit or vegetable products are sorted as soon as possible after harvesting.
The products which contain rot or which are diseased or off-colour, deformed or irregular in shape or subject to other defects are rejected. The products are then graded for size or weight and products of a substantially uniform grade are transferred to a heating unit which is preferably in the form of a microwave unit.
The products are then subjected to a high speed uniform heating to a ;3~2~3 temperature of approximately 50 to 85 C to deactivate the enzymes.
Testinq must be carried out in order to determine the amount of heating required in order to heat a particular fruit or vegetable product to the required temperature ran~e. In a particular microwave unit it will be apparent that the amount of enerqy required to heat products of one grade may be siqnificantly different from that required to heat products of another grade of the same product and it is ~or this reason that gradin~ is carried out before heatin~. Havin~ predetermined the settings required in the microwave unit to obtain the required heatinq for a particular grade of a particular product, it is possible to process all of the product of the particular qrade and then adjust the settings of the microwave unit when product of a different grade is supplied from the grader. In order to achieve a uniform heatinq of the fruit or veqetable product, the product is preferably caused to rotate in the microwave heating unit. This can be achieved by providing a simple rotating or tumbling mechanism which will cause the items to be rotated as they are advanced continuously through the microwave unit. Screw feeding devices suitable for this type of rotation are available in many mechanisms in which rotation of a fruit or vegetable product is required and will not therefor be described.
Mechanisms which will handle cut fruit, fruit salad and the like, without any loss of juice, are also available.
When the fruit or veqetable product has been heated in a microwave unit to a temperature of about 50 to 85C, it is removed 530~3 from the microwave unit and is then held at a temperature of about 70C for the appropriate predetermined dwell ~ime. When cut fruit or cut vegetables are being processed, a predetermined quantity of the product is placed in a container to ensure that co~plete deactivation of the enzyme and complete cooling is achieved.By ensuring that the fruit or vegetable product is held at the appropriate enzyme deactivating temperature ~or the appropriate dwell time complete deactivation of the enzymes is achieved.
Immediately after enzyme deactivation, the product is submerged in cold water at a temperature of about 1 to 5 C and cooled to the water temperature of about 1 to 5C and is retained in this body of water at this temperature for about thirty minutes.
In the case of cut fruits and vegetables, care must be taken to prevent water absorption into the product.
Cooling is preferably carried out by immediately submerging the fruit or vegetable products in cold water. The cooling water is preferably agitated to obtain rapid cooling. When the fruit or vegetable products are cooled to a substantially uniform temperature of about 1C, it is then removed from the cooling water and without allowing it to be reheated, it is then packaged in a hermetic sealed inert ~as filled Package. The packages in which the product is sealed may contain an ethylene absorbing chemical. After cooling, the fruit or vegetable product may be dried before packa~ing.
Alternatively, the fruit or vegetable product may be packaged with some water remaining therein. In either case, the fruit or vegetable product is packaged before it is allowed to warm up to any siqnificant extent from the temperature achieved in the coolinq ~530Z8 DSA-4l98-7 stage. The package which is used is preferably in a form suitable for use in subsequent display of the fruit or vegetable product for sale. It is important to note that the packaging must be capable of providing a hermatic seal which will not permit air, water, bacteria, yeast, mold, or the like, to enter the package.
Furthermore, the packaging material must be selected to ensure that it will not deteriorate under normal storage conditions. In addition, a blanket of nitrogen, carbon dioxide or any food approved inert gas may be provided in the package to ~urther inhibit deterioration during storaqe. Oxygen in the air causes oxidatior of many natural chemicals within the fruits and vegetables and for this reason air must be replaced by an inert gas.
The packaged fruit or vegetable products are then irradiated in an irradiation chamber of an irradiation device. The radiation dosage will vary depending upon the type of fruit or vegetable product which is to he processed. I have found that when using gamma wave radiation a dosage higher than 0.85 kgy. tends to damage to centain fruit. In addition in fruit/vegetables such as onions and garlic, internal discolouration (browning) takes place in the growth zones.
Any one of the microwave heating ovens which are presently available on the market may be used to heat the fruit or vegetable products. A suitable gamma wave food irradiation unit is manufactured by Atomic Energy of Canada ~td. and is identified by Model No. Js-8~00. Many other suitable units are available from other sources.
~2s53028 DS4-419~-7 A 1965 report issued by the surgeon general oE the U.S.A.
army indicates that foods irradiated up to absorbed doses of 5.6 KGY
with a cobalt 60 source of gamma irradiation or with electrons with enerqies up to 10 million electron volts have been found to be wholesome, i.e. safe and nutritionally adequate. In November, 1980 in Geneva the ~oint FAO/IAEA/Who expert committee on wholesomeness of Irradiated Foods concluded that the irradiation of any food commodity, up to overall, average dose of 10 KGY presents no toxicological hazard; hence toxicological testing of ~oods so treated is no lon~er reauired. Irradiation of foods up to an overall average dose of 10 KGY introduces no special nutritional or microbiological problems.
An apple wei~hing lfi5.4 grams taken from cold stora~e at 4.5 C (40 F) was placed in a microwave unit. The microwave was activated to emitt 750 watts for 95 seconds and as a result the apple was heated to an interior temperature of 71.1 C.
The apple was then submerged in a body of water which is at a temperature o~ 70 C and it is held in the water to ensure that it remains at a temperature of 70C about two minutes to ensure complete deactivation of the enzymes. The apple was then removed from this body of water and is immediatly submerged in cold water at a temperature of about 1~1 C and is retained in this body of water for about thirty minutes. The internal temperature of the apple was as a result cooled to a temperature of about 3.6 C.
After removal from the water the apple was placed in a plastic ba~. The bag was then flushed with nitrogen gas. The ba~
~253~28 ~ S4-4198-7 was then sealed and the ba~ and its contellts were then irradiated with 0.70 KGY.
After irradiation the bag and its contents were stored at room temperature.
A tomato weiqhing 153.9 grams was used instead of an apple. The initial temperature to of the tomato was 4.5 C.
The tomato was heated to 71.1 C for 93 seconds as in Example 1. All other treatment was the same as ~or the apple in Example 1.
A pepper (red bell) weighing 200.4 grams was used instead of an apple. The initial temperature of the pepper was 4.5C.
The pepper was heated to 71.1C (160F) for 115 seconds in the microwave as in Example ]. All other treatments and results were the same as for the apple in Example 1.
Example 4 Cut chilled (4.5C - 40F) fruit salad (1/2" cut) consisting of melon, pineapple, apple, peaches, weighing 165.0 grams was placed in a glass beaker size 42 mm x 90 mm and placed in a microwave unit.
The microwave unit was activated to emitt 750 watts for 96 seconds. The fruit salad had an interior temperature of 72.0C
(162F).
The beaker was removed from the microwave unit and held for about 2 minutes.
~Z53~Z8 The beaker and contents were placed in cold water (not to allow water to enter the top of the beaker) for 35 minutes where it reached a temperature of 4.0C (39F.).
The fruit salad was placed into a hermetic sealed plastic container, flushed with nitrogen qas and sealed.
The package was irradiated with 0.7 KGY.
After irradiation the package and its contents were stored at room temperature.
After storing the products produced in Examples 1 to 4 at room temperature for , the packayes were opened and the products were found to have retained most, if not all of their original freshness, flavour and texture.
Example 5 Example 4 was duplicated but neither heating nor enzyme deactivation was done.
The 165 qrams o fruit salad was placed in a hermetic sealed plastic container and flushed with nitrogen gas and sealed.
The package was irradiated with 1.2 KGY hefore complete sterility (as compared to 0.7 KGY with microwave). Further the enzymes were not deactivated. The product did not have the freshness, flavour or texture of the original fruit.
Combined microwave and irradiation have a synergistic effect on sterilization requiring less irradiation doseage.
Background of _v ntion Despite the fact that fresh Eruit and veqetables have been preserved by many methods, the systems which have been developed to date all tend to result in a loss of ~reshness durin~ processing or a loss of freshness aEter a short period of storage. In addition, the texture and ~lavour of the fruits and vegetables which are preserved by present methods is also signiEicantly changed.
It is well known to reErigerate or freeze fruit and vegetables in an attempt to prolong storage liee of these products.
It is also well known to use hermatic seal film, bags, packages or containers, with our without inert gases, to increase the storage life of Eresh Eruit and vegetables. In addition, attempts have heen made to increase storage life by subjecting the Eruits and veqetables to irradiation. While each of these techniques provides an improvment over the mere storing of the fruits and vegetables at ambient temperature, the systems have serious limitations whether used individually or in combination.
Some fruits such as papaya and manqo and the like cannot be frozen without destroying the texture and flavour. Furthermore, without the deactivation of enzymes, ethylene qas is produced and the flavour and texture of the products deteriorates rapidly, even ~53028 when refrigerated. Radapperation has proven to be the most effective long range chemical free way of preservin~ food such as fruit and vegetables. In this proces.s, the fruits and vegetables are cooked and are then placed in a hermatic sealed container which is then sterilized by an irradiation process. This process is not suitable for ~resh fruit or vegetable preservation because the texture of the flavour is destroyed.
Enzymes are a qroup of proteins found in living plant cells which catalyze a variety of chemical reactions. Over one thousand such enzymes have been discovered in fruits and vegetables~ When fruits and vegetables are harvested, it is normal for senescence to set in. During this period ethylene ~as is formed within the fruit or vegetables. This gas triggers the activation of the enzymes, e.~. breakdown of pectin, protein, etc., which causes a breakdown of the fruit or vegetables.
Enzymes are deactivated by heat to coa~ulate or denature at temperatures over 50C.
The freshness, texture and flavour of many fruits and vegetables will be adversely affected if the fruit or vegetable is held at the enzyme deactivating temperature beyond a critical dwell time which varies with different fruits or ve~etables. Generally, if a fruit or vegetable is heated to a temperature of 90C and is held at this temperature for ten minutes, the naturally occurring enzymes will be deactivated.
It is known that fruits and ve~etables can be damaged if subjected to excessive irradation and consequently it is desirable to minimize the radiation dosa~e used for the purpose of sterilizing ~53028 fruits and vegetables.
Research and reports from medical authorities .show that many people are allergic to sulphur dioxide. Sickness and death have resulted from consumption of sulphur dioxide. Sul~hur dioxide is used in fruit and vegetable salads, dried fruits, etc. to retain freshness, colour and to partially preserve.
The present process allows cut fruits and vegetables, e.g.
fresh fruit salad and fresh vegetable salad to be prepared, hold and eaten without the need to use sulphur dioxide as a preservative.
Summary of Invention It is an object of the present invention to provide a process which will substantially increase the storage life of fresh fruits and vegetables without destroyinq their freshness, texture or flavour.
Accordinq to one aspect of the present invention, a process for preserving the freshness, flavour and texture of fresh fruits or veqetable products comprisinq the steps of heating the fruit or vegetable product rapidly and uniformly by means of a microwave heatinq system to a temperature and retaining the product at the enzyme deactivating temperature for a dwell time sufficient to deactivate all of the natural enzymes which are present in the product without cooking the product, and immediately thereafter, cooling said ~roduct rapidly to a sufficient extent to remove the enzyme deactivating heat before any cooking of the product can occur, and to cool the product to a temperature which will inhibit deterioration of the freshness, flavour and texture thereof and ~2530Z8 shortly thereafter, while the product remains in said cold condition, packa~ing and hermetically sealing the cooled product in a container which contains an inert gas, irradiating the packaged product, using a food sterilizing form of radiation to an extent sufficient to sterilize the product and prevent the formation of degenerative qas in the product, without damaqing the product to thereby provide an enzyme-free, sterile and hermetically packagea fruit or vegetable product which has its fresh flavour and texture characteristics substantially unaltered and which can be stored without deterioration of freshness, flavour or texture for a long time.
The invention will be more clearly understood after reference to the following detailed specification read in conjunction with the drawinqs wherein:
Figure 1 is a diagram illustrating the various steps of the process of the present invention.
Fruits and vegetables which can be processed by the present invention include: apples, oranges, grapefruit, lemon, grapes, peaches, nectarines, olives, cherries, elderberries, avocado, mango, gooseberries, strawberries, raspberries, boysenberries, youngherries, bana~as, tomatoes, guava, pineapple, soursop, jackfruit, broccoli, cauliflower, carrots, peas, potatoes, french fries, oka, beets, onions and peppers.
Various other fresh fruit and vegetables are capable of beinq processed hy the present invention and the above list is intended to be representative rather than limiting.
;3028 Refore a particular type of fruit or vegetable is processed it is necessary to carry out some preliminery enzymic testing to determine~ its optimum enzyme deactivating dwell time. The optimum enzyme deactivatinq dwell time is the maximum time for which a particular type of fruit or vegetable may be maintained at the enzyme deactivating temperature without adversely affecting its freshness, texture and flavour. The temperature of the product should be controlled by suitable sensor devices to maintain the product at an even temperature. Samples of the particular fruit or vegetable which is to be processed should be heated to the required enzime deactivating temperature and held at this temperature for various time periods and then subjected to laboratory and taste tests to determine an appropriate dwell time. Periodic tests should also be carried out during production runs to ensure the the dwell time is correct. It is desirable to maximize the enzyme deactivating dwell time to thereby permit the sterilizing irradiation dosage to be minimized. If the product is overheated it will soften or rupture the cell walls of teh product and give the product a cooked flavour and texture.
As illustrated in Fiqure 1 of the drawings, the fruit or vegetable products are sorted as soon as possible after harvesting.
The products which contain rot or which are diseased or off-colour, deformed or irregular in shape or subject to other defects are rejected. The products are then graded for size or weight and products of a substantially uniform grade are transferred to a heating unit which is preferably in the form of a microwave unit.
The products are then subjected to a high speed uniform heating to a ;3~2~3 temperature of approximately 50 to 85 C to deactivate the enzymes.
Testinq must be carried out in order to determine the amount of heating required in order to heat a particular fruit or vegetable product to the required temperature ran~e. In a particular microwave unit it will be apparent that the amount of enerqy required to heat products of one grade may be siqnificantly different from that required to heat products of another grade of the same product and it is ~or this reason that gradin~ is carried out before heatin~. Havin~ predetermined the settings required in the microwave unit to obtain the required heatinq for a particular grade of a particular product, it is possible to process all of the product of the particular qrade and then adjust the settings of the microwave unit when product of a different grade is supplied from the grader. In order to achieve a uniform heatinq of the fruit or veqetable product, the product is preferably caused to rotate in the microwave heating unit. This can be achieved by providing a simple rotating or tumbling mechanism which will cause the items to be rotated as they are advanced continuously through the microwave unit. Screw feeding devices suitable for this type of rotation are available in many mechanisms in which rotation of a fruit or vegetable product is required and will not therefor be described.
Mechanisms which will handle cut fruit, fruit salad and the like, without any loss of juice, are also available.
When the fruit or veqetable product has been heated in a microwave unit to a temperature of about 50 to 85C, it is removed 530~3 from the microwave unit and is then held at a temperature of about 70C for the appropriate predetermined dwell ~ime. When cut fruit or cut vegetables are being processed, a predetermined quantity of the product is placed in a container to ensure that co~plete deactivation of the enzyme and complete cooling is achieved.By ensuring that the fruit or vegetable product is held at the appropriate enzyme deactivating temperature ~or the appropriate dwell time complete deactivation of the enzymes is achieved.
Immediately after enzyme deactivation, the product is submerged in cold water at a temperature of about 1 to 5 C and cooled to the water temperature of about 1 to 5C and is retained in this body of water at this temperature for about thirty minutes.
In the case of cut fruits and vegetables, care must be taken to prevent water absorption into the product.
Cooling is preferably carried out by immediately submerging the fruit or vegetable products in cold water. The cooling water is preferably agitated to obtain rapid cooling. When the fruit or vegetable products are cooled to a substantially uniform temperature of about 1C, it is then removed from the cooling water and without allowing it to be reheated, it is then packaged in a hermetic sealed inert ~as filled Package. The packages in which the product is sealed may contain an ethylene absorbing chemical. After cooling, the fruit or vegetable product may be dried before packa~ing.
Alternatively, the fruit or vegetable product may be packaged with some water remaining therein. In either case, the fruit or vegetable product is packaged before it is allowed to warm up to any siqnificant extent from the temperature achieved in the coolinq ~530Z8 DSA-4l98-7 stage. The package which is used is preferably in a form suitable for use in subsequent display of the fruit or vegetable product for sale. It is important to note that the packaging must be capable of providing a hermatic seal which will not permit air, water, bacteria, yeast, mold, or the like, to enter the package.
Furthermore, the packaging material must be selected to ensure that it will not deteriorate under normal storage conditions. In addition, a blanket of nitrogen, carbon dioxide or any food approved inert gas may be provided in the package to ~urther inhibit deterioration during storaqe. Oxygen in the air causes oxidatior of many natural chemicals within the fruits and vegetables and for this reason air must be replaced by an inert gas.
The packaged fruit or vegetable products are then irradiated in an irradiation chamber of an irradiation device. The radiation dosage will vary depending upon the type of fruit or vegetable product which is to he processed. I have found that when using gamma wave radiation a dosage higher than 0.85 kgy. tends to damage to centain fruit. In addition in fruit/vegetables such as onions and garlic, internal discolouration (browning) takes place in the growth zones.
Any one of the microwave heating ovens which are presently available on the market may be used to heat the fruit or vegetable products. A suitable gamma wave food irradiation unit is manufactured by Atomic Energy of Canada ~td. and is identified by Model No. Js-8~00. Many other suitable units are available from other sources.
~2s53028 DS4-419~-7 A 1965 report issued by the surgeon general oE the U.S.A.
army indicates that foods irradiated up to absorbed doses of 5.6 KGY
with a cobalt 60 source of gamma irradiation or with electrons with enerqies up to 10 million electron volts have been found to be wholesome, i.e. safe and nutritionally adequate. In November, 1980 in Geneva the ~oint FAO/IAEA/Who expert committee on wholesomeness of Irradiated Foods concluded that the irradiation of any food commodity, up to overall, average dose of 10 KGY presents no toxicological hazard; hence toxicological testing of ~oods so treated is no lon~er reauired. Irradiation of foods up to an overall average dose of 10 KGY introduces no special nutritional or microbiological problems.
An apple wei~hing lfi5.4 grams taken from cold stora~e at 4.5 C (40 F) was placed in a microwave unit. The microwave was activated to emitt 750 watts for 95 seconds and as a result the apple was heated to an interior temperature of 71.1 C.
The apple was then submerged in a body of water which is at a temperature o~ 70 C and it is held in the water to ensure that it remains at a temperature of 70C about two minutes to ensure complete deactivation of the enzymes. The apple was then removed from this body of water and is immediatly submerged in cold water at a temperature of about 1~1 C and is retained in this body of water for about thirty minutes. The internal temperature of the apple was as a result cooled to a temperature of about 3.6 C.
After removal from the water the apple was placed in a plastic ba~. The bag was then flushed with nitrogen gas. The ba~
~253~28 ~ S4-4198-7 was then sealed and the ba~ and its contellts were then irradiated with 0.70 KGY.
After irradiation the bag and its contents were stored at room temperature.
A tomato weiqhing 153.9 grams was used instead of an apple. The initial temperature to of the tomato was 4.5 C.
The tomato was heated to 71.1 C for 93 seconds as in Example 1. All other treatment was the same as ~or the apple in Example 1.
A pepper (red bell) weighing 200.4 grams was used instead of an apple. The initial temperature of the pepper was 4.5C.
The pepper was heated to 71.1C (160F) for 115 seconds in the microwave as in Example ]. All other treatments and results were the same as for the apple in Example 1.
Example 4 Cut chilled (4.5C - 40F) fruit salad (1/2" cut) consisting of melon, pineapple, apple, peaches, weighing 165.0 grams was placed in a glass beaker size 42 mm x 90 mm and placed in a microwave unit.
The microwave unit was activated to emitt 750 watts for 96 seconds. The fruit salad had an interior temperature of 72.0C
(162F).
The beaker was removed from the microwave unit and held for about 2 minutes.
~Z53~Z8 The beaker and contents were placed in cold water (not to allow water to enter the top of the beaker) for 35 minutes where it reached a temperature of 4.0C (39F.).
The fruit salad was placed into a hermetic sealed plastic container, flushed with nitrogen qas and sealed.
The package was irradiated with 0.7 KGY.
After irradiation the package and its contents were stored at room temperature.
After storing the products produced in Examples 1 to 4 at room temperature for , the packayes were opened and the products were found to have retained most, if not all of their original freshness, flavour and texture.
Example 5 Example 4 was duplicated but neither heating nor enzyme deactivation was done.
The 165 qrams o fruit salad was placed in a hermetic sealed plastic container and flushed with nitrogen gas and sealed.
The package was irradiated with 1.2 KGY hefore complete sterility (as compared to 0.7 KGY with microwave). Further the enzymes were not deactivated. The product did not have the freshness, flavour or texture of the original fruit.
Combined microwave and irradiation have a synergistic effect on sterilization requiring less irradiation doseage.
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for preserving the freshness, flavour and texture of fresh fruits or vegetable products comprising the steps of:
a) heating the fruit or vegetable product rapidly and uniformly by means of a microwave heating system to an enzyme deactivating temperature and retaining the product at the enzyme deactivating temperature for a dwell time suf-ficient to deactivate all of the natural enzymes which are present in the product without cooking the product, and immediately thereafter, b) cooling said product rapidly to a sufficient extent to remove the enzyme deactivating heat before any cook-ing of the product can occur, and to cool the product to a temperature which will inhibit deterioration of the freshness, flavour and texture thereof and shortly thereafter, while the product remains in said cold condition, c) packaging and hermetically sealing the cooled product in a container which contains an inert gas, d) irradiating the packaged product, to sterilize the product and prevent the formation of degenerative gas in the product, without damaging the product to thereby provide an enzyme-free, sterile and hermetically packaged fruit or vegetable product which has its fresh flavour and texture characteristics substantially unaltered and which can be stored without deterioration of freshness, flavour or texture for a long time.
a) heating the fruit or vegetable product rapidly and uniformly by means of a microwave heating system to an enzyme deactivating temperature and retaining the product at the enzyme deactivating temperature for a dwell time suf-ficient to deactivate all of the natural enzymes which are present in the product without cooking the product, and immediately thereafter, b) cooling said product rapidly to a sufficient extent to remove the enzyme deactivating heat before any cook-ing of the product can occur, and to cool the product to a temperature which will inhibit deterioration of the freshness, flavour and texture thereof and shortly thereafter, while the product remains in said cold condition, c) packaging and hermetically sealing the cooled product in a container which contains an inert gas, d) irradiating the packaged product, to sterilize the product and prevent the formation of degenerative gas in the product, without damaging the product to thereby provide an enzyme-free, sterile and hermetically packaged fruit or vegetable product which has its fresh flavour and texture characteristics substantially unaltered and which can be stored without deterioration of freshness, flavour or texture for a long time.
2. A process as claimed in claim 1, wherein the product is heated to a temperature of about 50° to 70° C.
3. A process as claimed in claim 1, wherein the product is cooled by immersing it in water at a temperature of about 1°C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000491661A CA1253028A (en) | 1985-09-26 | 1985-09-26 | Process for preserving fresh fruit and vegetables |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000491661A CA1253028A (en) | 1985-09-26 | 1985-09-26 | Process for preserving fresh fruit and vegetables |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1253028A true CA1253028A (en) | 1989-04-25 |
Family
ID=4131475
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000491661A Expired CA1253028A (en) | 1985-09-26 | 1985-09-26 | Process for preserving fresh fruit and vegetables |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1253028A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2758439A1 (en) * | 1997-01-17 | 1998-07-24 | Francoise Marie Odil Guillaume | Preparation and pre-cooking of fruit for tarts |
| US20140272042A1 (en) * | 2013-03-15 | 2014-09-18 | Thomas D. Gillette | Systems and methods for packaging food products |
-
1985
- 1985-09-26 CA CA000491661A patent/CA1253028A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2758439A1 (en) * | 1997-01-17 | 1998-07-24 | Francoise Marie Odil Guillaume | Preparation and pre-cooking of fruit for tarts |
| US20140272042A1 (en) * | 2013-03-15 | 2014-09-18 | Thomas D. Gillette | Systems and methods for packaging food products |
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