FR2594642A1 - HUMIDITY INTERMEDIATE PLANT PRODUCTS AND THEIR MANUFACTURE - Google Patents

Abstract

Disclosed is a process for producing an intermediate moisture plant product which is microbiologically stable at water activity levels in the range 0.5 to 0.85 and which is free of additives used to prevent microbial contamination. According to the invention, a fruit or vegetable is dehydrated to reduce its moisture content to 10-50%, and then the resulting plant product is maintained in an atmosphere free or substantially free of oxygen. Applications: dehydrated fruits and vegetables retaining the color, flavor and aroma of fresh produce.

Description

The present invention relates to a method for producing

  fruits and vegetables with an intermediate moisture content

  after named plant products. The term "vegetables" is used here to refer to all types of products normally considered as plants including leaves, roots, bulbs and stems and their fruiting, matured or not. This term also includes non-edible vegetable matter. The term "fruits" refers to the sweet-fleshed fructifications of plants, normally referred to as fruits.

  Dehydrated vegetables have long been commercially

  cialised. They can be produced by drying in hot air, drying

  by freezing, drying by detonation or explosion, osmotic drying

  tick or other techniques. Whatever the technique used for drying, distribution and commercial use of dehydrated feces has been limited to products which are usually hard and brittle, with moisture contents

  between 2% and 8% and ordinary water activities-

  less than 0.5. If the moisture content or water activity exceeds these values, the products are considered as unstable, with a relatively rapid and undesirable deterioration of color, flavor and aroma. If the water activity rises

  above 0.6, the products are sensitive to the micro-action

  bienne. Vegetables at these low moisture levels have the following disadvantages:

1. They rehydrate slowly.

  2. Usually, after reconstitution, they have

  unpleasant taste of "dehydrated product" or "hay".

  3. They are excessively brittle, break easily, pierce packaging materials as a result of sharp edges; and 4. Their texture after rehydration is still somewhat relaxed, as a result of irreversible changes in cell structures that occurred during the manufacturing process.

low moisture content.

  In commercial practice, the vegetables can be dried in the initial stages of the process at a moisture content of 10 to 15% in a relatively short time. The final stages of drying, in which the moisture content is lowered to the mentioned values of 2 to 8%, are slow and

  expensive and it is during these last stages of dehydration

  most deteriorations take place.

  The problems of time and quality associated with

  this final drying step have been overcome in some-

  measured by processes such as dehydration freezing

  where the product is first partially dried, then frozen, and dehydrated with salt, where the product is partially

  dehydrated, then preserved in brine. However, the disadvantages

  are the cost of freezing and storing

  on the one hand, and the presence of liquid brine and

  high salt levels, on the other hand.

  Australian Patent No. 532,414 (to Lewis and Lewis) discloses a process in which salt is easily introduced, with or without other solutes, into partially dehydrated vegetables to produce intermediate moisture products of good stability having levels of relatively high water activity (0.45-0.85) and relatively high moisture contents (up to 25%). The production of these vegetables involves a dehydration process in two stages separated by a short stage

impregnation.

  Applicant has experimented with moisture content of vegetables during dewatering and water activity; these experiments revealed that, as the moisture content of the Vegetable is reduced, the water activity

  falls from just under 1.0 for fresh vegetable, up to

  below 0.5 when the moisture content of the vegetable is reduced to about 10%. As the moisture content of vegetables

  is reduced below this value, they become progressively

  harder and more brittle and the duration of rehydration

increases.

  It is well known that to protect foods from bacterial growth, the food must have a water activity of less than 0.85. However, growth of molds and yeasts has been observed in an environment with water activity as low as 0.6 (see JA Troller, Food Technology 1979 Jan., pp 72-75, Troller JA and Cristian JHB "Water activity of Foods "Academic Press 1981). It was therefore common practice to add artificial preservatives such as sorbic acid and sorbates or sulfites, etc., to foods in the water activity range of 0.60 to 0.85. to inhibit the growth of yeasts and molds. In many countries, food law recognizes the risk of commercial distribution of processed foods over a water activity of 0.85 by the fact that it is

  necessary to store and distribute these foods in a chilled state.

  The plaintiff has discovered that in the range of

  With water between 0.5 and 0.85, partially dehydrated vegetables are usually of excellent color and are mostly still pliable, rehydrate very quickly and have

  in the rehydrated state an excellent flavor, texture and aroma.

  While most vegetables partially dehydrated to water activities of 0.5 to 0.85 have a slowly degraded flavor and color and may be subject to microbiological contamination if not treated with preservatives, the plaintiff has surprisingly discovered that fruits and vegetables in this range of activity

  of water that has been studied, if they are conditioned in a

  oxygen-free, remain in excellent condition for long periods, in some cases more than 2 years at room temperature. Commercial dried fruits that are currently available tend to have a leather-like stiff texture, a dark, unpleasant color and a typical caramel flavor, without the aroma of fresh fruit. The high content of sulfur dioxide, usually between 0.2 and 0.3%, is often unpleasant

to taste.

  The applicant has discovered that a wide variety of fruits, including apples, peaches or pears, plums, bananas, papayas and pineapples, can be prepared having an excellent flavor and aroma by treating the fruits as indicated here for vegetables . With some fruits such as peaches, apples and pears, which darken easily due to the action of an enzyme when the flesh is cut, it is desirable to treat the fruit pieces prepared by sulfur dioxide, so that the sulfur dioxide content of the dried fruit is between 0.01 and 0.1%. Other fruits such as plums, grapes and raspberries do not need pretreatment by

  sulphur dioxide. The most common fruits have lower pHs

  at 4.5 and when dehydrated, the pH is further lowered by acid concentration. It is therefore "harmless" from the bacteriological point of view of dehydrating acidic fruits to a water activity higher than the upper limit of 0.85 mentioned for vegetables. The upper limit for these fruits

  Acids strongly depend on the desired final texture of the product.

  For the most part, dehydrated fruits at 50% of their initial weight tend to be soft with a sensation of moisture, but the degree of dehydration chosen is a matter of preference and depends on the use for which the fruit is intended. Samples of various acidic fruits with water activities up to 0.95 and moisture contents of 20-60%, when packaged in the absence of oxygen, are stable

  for several months of storage at room temperature.

  Dehydrated fruits with water activities of 0.70-

  0.95, with moisture contents of 20 to 60% and packaged in an oxygen-free environment have a tenderness and a

  excellent flavor and are generally quite acceptable.

  For fruits to which sulfur dioxide or sulphite must be added in order to preserve the color, the quantity used is much lower than that usually found in

  conventional dried fruits and flavor is therefore preferred.

  These fruits, packed in an oxygen-free atmosphere, retain their color and aroma to a remarkable degree and have quite different tenderness and acceptability of conventional dried fruits. The addition of sulfur dioxide is used to preserve the fruit's tiller and is carried out at much lower levels than those normally used.

in dried fruits.

  The products of plants that are not acidic, that is,

  pH above 4.5, can be prepared for water activities greater than 0.85, packed in an oxygen-free atmosphere

  and kept refrigerated for long periods of time without

  nation and maintaining excellent quality. Although these products need to be kept in the refrigerator, they have the advantage of giving a product of long shelf life, light weight for transport, which is not bulky, does not crush or

  does not break, has a high quality and is easily rebuilt.

  According to one aspect of the invention there is provided a method for producing a moisture intermediate plant product which is microbiologically stable to water activities in the range of 0.5 to 0.85 and free of the agents used. to avoid microbial contamination (preservatives), characterized in that fruits or vegetables are partially dehydrated until the moisture content is reduced to 10 to 45%, and then the resulting product is maintained in an atmosphere free or substantially free of oxygen. Preferably, the product is packaged in a container having a low oxygen permeability, the free oxygen of which is entirely or almost entirely eliminated and optionally replaced by an oxygen-free inert gas, or else said product is kept under vacuum. The packaging called "under gas" food is not new in itself. For the most part, however, an inert gas or vacuum has been used to prevent the development of rancidity in products such as milk powder, coffee, nuts, etc. Gas packaging has also been used for traditionally dried out vegetables such as carrots to try to reduce the "hay" odor that is developing in some of these products. Gas packaging has also been used with fresh fruits and vegetables to extend shelf life in the refrigerator, but use in these circumstances is primarily to regulate the breathing of the plant tissue. In the literature (Advances in Food Research, Volume I, pages 342-346, 1948, Academic Press, New York, USA), mention has been made of the effect of oxygen on the deterioration of dried fruit. These studies, however, relate to the

  or blackening of these fruits at conventional moisture levels.

  The effect of oxygen on microbiological stability and quality above normal moisture levels is not mentioned or considered. Oxygen-free packaging allows the production of intermediate moisture products of between 10 and 45%, with water activity levels of 0.5 to 0.85, good shelf life at ambient temperatures and excellent color retention and quality. By the additional use of the storage in a refrigerator, an interesting shelf life can be obtained for a plant product maintained in a free or substantially oxygen-free atmosphere.

  at water activity levels of more than 0.85.

  In one embodiment of the invention, oxygen is removed from a package of the plant product by means of pumps and, in another embodiment of the invention,

  using oxygen absorbers placed in the package.

  In another aspect, the invention relates to a moisture intermediate plant product which is bacteriologically stable to water activities in the range of 0.5 to 0.85 and which is free of artificial preservatives, said product of plant being kept in a free atmosphere

or substantially free of oxygen.

  In most cases, the quality of copservation of the product is even better than the oxygen is eliminated more completely. For storage, the product should be packed in oxygen impervious containers such as glass jars or jars, or in flexible packaging materials with low oxygen permeability such as laminates of leaves

  of aluminum or transparent laminates of

  vinylidene or similar materials.

  In the package, the oxygen must be removed from the container and replaced with an oxygen-free inert gas such as nitrogen or a mixture of these gases and / or oxygen scavengers such as finely pulverized iron in bags suitably

  prepared, must be incorporated into the packaging.

  High speed inert gas packaging equipment is commonly available, as are vacuum packaging devices. Similarly, we can mechanize

  the operation of introducing bags of oxygen absorbers.

  Other oxygen-absorbing systems are described in the literature.

  technical background (Lewis, Rambottom and Craine, US Patent

  No. 3,419,400; Buckner, N., FRG Patent No. 81 48 240) and those

  They can be used according to their cost and efficiency. With many vegetables such as carrots, red peppers and sweet potatoes, prepared in this range of water activities, additives are not needed and excellent color retention is achieved. With other vegetables, such as potatoes and onions, and with fruits, it may be necessary to add small amounts of sulphite or sulfur dioxide before packaging to reduce the color change during storage . However, sulfur dioxide serves to avoid color change and does not need to be used in the amounts commonly used to inhibit

  the growth of yeasts and molds.

  According to another embodiment of the invention, the fruits or vegetables are cut and cut as appropriate for dehydration. They are then dehydrated in any conventional manner, with or without prior bleaching in steam, water or other means, up to a water activity of between 0.5 and 0.85 for vegetables, or between 0.70 and 0.90 for fruits. They may be optionally treated before, during or after dehydration with sufficient levels of sulfur dioxide or sulfite and / or other additives to prevent change during storage. Either before, during, or after dehydration, fruits or vegetables may be flavored or seasoned or treated with vitamins, minerals, or. colorants, etc. as required. Finally, they are packaged and maintained in a free or substantially oxygen free atmosphere. An oxygen-free atmosphere may additionally or alternatively be kept in the package by

  the absorption of oxygen in the packaging by the use of absorb-

  different types of oxygen such as iron powder,

glucose-glucose oxidase, etc.

  The following examples illustrate the invention without

however, limit its scope.

Example 1

  Sweet potatoes Sweet potatoes with yellow flesh are peeled and cut into 3 mm thick slices. Steam bleached for 2 minutes, then washed with a jet of water and

  place on a tray in a dehydrator.

  Sweet potatoes are dried to moisture contents of 18.3%, 14.8% and 10.7% at which the activities

  of water are 0.82, 0.77 and 0.61, respectively.

  All samples are packaged in aluminum and polyethylene laminated foil bags and welded in a nitrogen atmosphere (after evacuation). We keep

  samples at each moisture content at 40 C and at the temperature

  ambient temperature (about 22 C). The samples at 40 C are still in excellent condition with regard to flavor and color after 4 months of storage. At room temperature, sweet potatoes are in excellent condition after 13 months of storage. With respect to storage stability at 40 C, it is estimated that the product would have

  a shelf life of about 2 years at room temperature.

Example II

  Potatoes Potatoes are peeled and cut into strips of 3 mm x 3 mm. These strips are blanched in boiling water for 3 minutes, washed to remove starch at the surface and placed in the dehydrator. When the moisture content is about 40%, the potato pieces are removed from the dehydrator and treated in a drum washer with a solution of sodium sulphite so that the final sulfur dioxide content of the apples of dried earth is approximately 0.025%. The potatoes are returned to the dehydrator and dried to a moisture content of 15.6%. The activity

  Potato water at this moisture content is 0.85.

  The pieces have a good pale color and are not brittle.

  They are packed under nitrogen in foil bags and

keep at room temperature.

  We open the samples every month. After five months, the products are excellent, but after six months, the pieces have taken a slight defective color, but they have a good aroma and

a good flavor.

Example III

  Carrots Carrots are peeled and rinsed into strips of 3 mm x 3 mm section. Steam bleach was dried for 4 minutes and dried in a continuous bed dryer at 70 ° C. Samples were removed at moisture contents of 29.7%, 13.6% and 0%. The water activities of these samples are 0.82,

0.65 and 0.50, respectively.

  When added to boiling water, the samples cook in 3 to 5 minutes and, when cooked,

  all have excellent flavor and texture.

  The samples are packaged in a clear laminate film made of layers of polyvinylidene chloride, "nylon" and polyethylene and welded after the addition of a small bag of oxygen scavenger ("Ageless", manufactured by the

  Mitsubishi Gas and Chemical Co., Tokyo, Japan).

  After thirteen months of storage at room temperature, the three samples all retained an aroma, flavor and

an excellent color.

Example IV

  Red peppers Empty red peppers and cut into slices of about 7 mm. They are dried at 70 ° C. in a continuous bed forced air dehydrator to a moisture content of 20%.

  At this moisture content, they have a water activity of 0.67.

  The pepper slices have a bright red color, a pliable texture and, when cooked, they look like color, texture and flavor with freshly baked peppers. The dried slices are wrapped in a low permeability laminate film

  to oxygen with bags of oxygen absorber.

  The peppers retain their bright color for about 8 weeks when kept at 40 C and they still have an excellent color and flavor after thirteen months of

storage at room temperature.

Example V

  Peaches Golden-style peaches are pitted and pitted and cut into Dortions of about 1 cm in the thickest part. They are immersed for 5 minutes in a solution of

  1% sodium sulphite and dried at 70-80 ° C. in a dehydrogenation

  continuous bed drafter until the moisture content is 23.4%. The water activity of peaches at this moisture content

  is 0.83. The sulfur dioxide content is 0.064%.

  We pack the dried peach pieces in a

  low oxygen permeability film with oxygen absorbers.

  After two months of storage at 40 C, they do not show signs

  of contamination and still have a bright golden orange color.

  Fruits stored at room temperature have a texture, a

  excellent flavor, aroma and color after eight months.

Example VI

  Apples We peel and seed Jonathan variety apples and cut them into 1 / 12th pieces of the fruit each. The pieces are immersed for 5 minutes in 0.1% sodium sulphite solution, drained and dehydrated at 70 ° C until their moisture content is reduced to 42.7% and their activity is reduced.

  of water at 0.93. The sulfur dioxide content is 0.085%.

  The apple pieces are wrapped in a film of low oxygen permeability with an oxygen absorber and

  they are stored in a refrigerator below 5 C.

  After seven months of storage, the apples show no signs of deterioration and they have a color, a flavor

and an excellent aroma.

Example VII

  Apples Granny Smith apples are peeled and seeded and cut into 3 mm thick slices. The slices are immersed in 1% sodium sulfite solution for 1 min and then drained. The apple slices are dried in a continuous-bed dehydrator at 70 ° C. to a moisture content of 37.7% at which they have a water activity.

  0.79. The sulfur dioxide content is 0.041%.

  The slices are packed under nitrogen in foil bags and held at room temperature. After ten months, the fruit is still white and has an aroma and

a fresh fruit flavor.

  Exemole VIII Pears Packham pears are peeled and seeded and cut into pieces of about 1 / 8th each of the whole fruit. The fruit pieces are immersed for 1 minute in 1% sodium sulphite solution, drained and dried in a 70 C continuous bed dehydrator to a moisture content of 43.4% water activity of 0.82. Content

  sulfur dioxide final is 0.096%.

  The pears have a pale color and a flavor and

an aroma of fresh fruit.

  The pear pieces are wrapped in a low oxygen permeability film with branded oxygen absorbers. The dried fruit does not show any apparent contamination or deterioration of the color or flavor after ten

  month of storage at room temperature.

  In some cases, for example for grapes, the use of sulfur dioxide is not necessary. EXAMPLE IX Grapes Seed-free Thompson variety grapes are dipped in 2.5 X potassium carbonate solution to make the skin more permeable and dried at 700 C to a water activity of 0.85. The moisture content is 35.5%. The grapes are packed under nitrogen in a laminated sheet bag. After four months of storage at room temperature, the grapes are

in excellent condition.

  It is understood that the invention is not limited to

  preferred embodiments described above as illus-

  tion and that the person skilled in the art may make various modifications

  tions and various changes without departing from the framework and

of the spirit of the invention.

R E V E N D I C AT I 0 N S

  A process for producing a moisture intermediate plant product which is microbiologically stable at water activity levels in the range of from 0.5 to 0.85 and which is free of the additives used to prevent microbial contamination. characterized in that a fruit or vegetable is dehydrated to reduce its moisture content to 10 to 50, and then the resulting plant product is maintained in a free atmosphere.

or substantially free of oxygen.

  2. Method according to claim 1, characterized in that

  that the fruit or vegetable is treated before, during or after the dehy-

  dratation with one or more additives selected from color change inhibitors, flavoring agents, seasoning agents, mineral substances, vitamins and

dyes.

  3. Method according to claim 1, characterized in that said plant product is packaged in a container and oxygen

  is removed from the container by means of pumps.

  4. Method according to claim 1, characterized in that oxygen is removed from said container by oxygen absorbers

places in the container.

  5. Method according to claim 3 or 4, characterized

  in that said oxygen is replaced by an inert gas.

  6. Process according to claim 5, characterized in that

that said inert gas is nitrogen.

  7. The method of claim 1, characterized in that said plant product is bleached before said dehydration step. A process for producing an intermediate moisture content fruit which is microbiologically stable at water activity levels of 0.70 to 0.90 and which is free from the additives used to prevent microbial contamination, characterized in that that said fruit is treated with a sulphite solution to give said fruit a sulfur dioxide content of between 0.01 and 0.1%, said fruit is dehydrated to reduce its moisture content by up to 20 to 60% and then maintaining the resulting food product in a free or substantially oxygen free atmosphere. 9. A method according to claim 8, characterized in that the fruit is treated before, during or after dehydration with one or more additives selected from color change inhibitors, flavoring agents, seasoning agents, substances minerals, vitamins and dyes. 10. The method of claim 8, characterized in that said fruit is packed in a container and the oxygen is removed

of the container by means of pumps.

  11. The method of claim 8, characterized in that the oxygen is removed from said container by oxygen absorbers

placed in the container.

  The method of claim 8, characterized in that

  said oxygen is replaced by an inert gas.

  13. The method of claim 8, characterized in that

said inert gas is nitrogen.

  14. A plant product which is midrobiologically stable at water activity levels of 0.50 to 0.85 and which is free from the agents used to prevent microbiological contamination, said plant product having a reduced moisture content up to at 10 to 45% and being kept in an atmosphere free or substantially

free of oxygen.

  15. Plant product, characterized in that it is

  manufactured by the process according to any of the claims

1 to 13.