JPH02182180A - Frozen food and making thereof - Google Patents

Abstract

PURPOSE: To obtain a frozen food product which contains a frozen food or food mixture, reduces the moisture contents rather than that in case of eating and can easily permeate thawing water. CONSTITUTION: Concerning the frozen food product, this food product contains frozen water and non-frozen water and further contains more than one kind of physiologically permissible water soluble salts sufficiently holding the non- frozen water so that the existent quantity of every salt is less than 4wt.% of the frozen product but its total quantity is less than 10wt.% of the frozen product when salts more than two kind exists.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to food products, their production and uses. This food product is intended for human or animal applications.

There are already a number of foods on the market that are relatively easy to prepare or require only relatively simple processing to make them suitable for consumption. Such products are commonly referred to as ``convenience foods''.

There are generally three types of known food products: canned products;
It is broadly divided into dried products and frozen products. However, each of these foods has its own problems or drawbacks.

Canned food products are bulky and completely dependent on hermetic seals, so the quality of the product is maintained depending on the integrity of the can.

Dry foods are often the least palatable. In particular, rehydratable dry products tend to be perceived by consumers as being of poor quality and not palatable, and still have a number of technical problems that need to be resolved. Significant efforts have been made to find ways to preserve palatability, flavor and texture by reducing the denaturing effects of heating and solute concentration. Some products have had some success on a laboratory scale, but have encountered significant difficulties when brought to a commercial scale.

Although frozen foods have rapidly become popular over the past 15 years, particularly in the last five years as home freezers have become more prevalent, there are still problems with their use.

The current frozen food market can be roughly divided into the following three categories.

(1) Uncooked frozen convenience foods such as cooked frozen vegetables, fish fingers, and beef burgers that do not require thawing before cooking. However, apart from using freezing methods for food storage, it is also known to use freezing methods for concentrating products. The ice produced during freezing of a liquid product (eg, fruit juice) can be removed from the product (eg, fruit juice) to produce a product with a low moisture content that is reconstituted.

The removal of most ice under vacuum (lyophilization) is an extreme case, and this method produces products that can be immediately rehydrated, such as instant coffee. An essential limitation of freeze-concentration is that the method can only be applied to liquids. Thus, although freeze-drying is applicable to both solids and liquids, the resulting product is designed to be stable under room temperature conditions, and although the product can be quickly reconstituted, it Taste or texture is acceptable.

It is an object of the present invention to provide a stored food product that can be quickly and easily made into a diet, with acceptable or advantageous organoleptic properties.

According to the present invention, frozen foods or food mixes can be prepared in small pieces or boil-in-the-box to eliminate the need for frozen foods or food mixes and thawing.
-bag-foods) must have an artificially widened surface.

Cooking and preparation times for these foods are typically 5 to 25 minutes.

(2) Uncooked frozen bulk foods such as frozen whole chickens or bone-in meat chunks. These products must be thawed before cooking and the total preparation time may exceed 24 hours.

(3) Frozen finished meals and cooked ready-to-eat foods such as roasted meat slices.

These require heating in a conventional oven for more than 10 minutes or expensive alternatives such as microwave heating.

All of these products exhibit the same major flaws. That is, they require costly thawing and/or cooking to render them suitable for consumption.

wherein the frozen food product or mixture thereof has a water content lower than the water content at the time of consumption and is easily penetrated by thawed water, the food product comprising frozen water and unfrozen water. water and in addition, the amount of individual salts present in the frozen product is sufficient to retain unfrozen water and one or more physiologically acceptable water-soluble salts in the food product.
% by weight or less and the total amount of two or more salts, if present, is less than 10% by weight of the frozen product.

The product of the invention is reconstituted by adding an amount of warm or hot water to restore the moisture content of the product to its normal value while simultaneously raising the temperature of the product to the temperature normal for feeding.

According to the invention, the water content of a food product or food mixture is adjusted to a level lower than the normal value for said food product: before, during or after said water content adjustment, at least one physiologically acceptable water-soluble salt is added to said food product. and freezing said food having a low moisture level comprising said salt to produce a frozen food product comprising frozen water and unfrozen water and readily permeable to thawing water. A method,
The amount of salt added is at least sufficient to retain unfrozen water in the product, provided that each salt
% by weight or less and the total amount of two or more salts, if present, is less than 10% by weight of the frozen product.

It is preferred to reduce the moisture content of the food to a level within the range of 30 to 80%, preferably 35 to 60% and more preferably 40 to 55% of the original moisture content of the crude, unprocessed food.

Moisture adjustment may be achieved by removing water from fresh foodstuffs or by partially rehydrating dry, optionally powdered materials. This latter method can be used, for example, to reconstitute meaty products from artificially shaped vegetable proteins, and when added to food temperature, the moisture content of the final product is approximately the moisture content expected for a frozen product. Adjust the initial moisture content so that

This regulation does not place any fixed limits on either the temperature or the relative amount of water added in the thawing/rehydration step. These two factors completely depend on the type of product. Meat-based products can be manufactured to be eaten by animals at 20-40°C and can also be produced by reducing the initial moisture content, by increasing the amount of added water or by increasing the temperature of the added liquid. By making humans 50-60'
It is possible to produce it for consumption at C. The total amount of heat given (water temperature x volume) is important.

(3) Some of the water in the product should be in an unfrozen state. This amount is controlled by the water-soluble salt content of the product. The aqueous phase of a solution of a given solute in contact with ice always has the same concentration at equilibrium. The higher the amount of activating salt (usually sodium chloride), the lower the freezing temperature.

The products obtained according to the invention are able to combine the properties of both the deliciousness of frozen foods and the ease of preparation of texture and rehydration foods. It is possible and highly desirable to both thaw and rehydrate on the order of seconds and certainly within minutes.

Three factors should be considered for optimal results:

(1) Frozen products must be porous or otherwise permeable so that thawing and rehydration occur quickly and uniformly.

In order to obtain a product with such properties, a product with a small particle size is manufactured or a large piece is appropriately processed with a suitable structure. An important preferred feature of the present invention is based on the discovery that food chunks or pieces can be used in products, and that these chunks or pieces, when properly processed, also thaw and rehydrate rapidly.

(2) The amount of water (ie, unfrozen) that dissolves the appropriate amount of hot water into the frozen product at a given temperature is also increased. Since the specific heat of water is 1 cal/g, and the latent heat of fusion of ice is 80 cal/g, controlling the amount of frozen water is necessary for the final temperature of the product. Eighty times as much heat is removed from the added water to melt each gram of ice as is required to raise the temperature of 1 gram of melted ice by 1 degree Celsius. Therefore,
The temperature at which the product is eaten can be controlled by the ratio of frozen/unfrozen water in the product. It is possible to calculate the relationship between water content, soluble solids content, and temperature and amount of added water in the product to give the desired dietary temperature and concentration.

For example, if a frozen product consists of unfrozen water (containing a small amount of soluble food solids) ag, frozen water bg and food solids cg, and the temperature is -'C, it is further added to water dg which is initially at 10 T°C. The specific heat of water is 1, the specific heat of ice is 0.3, the specific heat of food solid is 0.8, and the latent heat of fusion of ice is 80 cal. /g, the following equation is obtained.

a(K+P)+b((1,3+BO+P)+0.8c
(K+P)=d(T-P) (1) a+b+c+d Estimating that the final reconstituted product should contain 1% (typical value) of sodium chloride provided by the frozen product salt. Since the concentration of sodium chloride solution in equilibrium with ice at -20°C is about 20%, the following formula: % Formula % Finally, expressing the result as a percentage, a + b + c = 100... ”
(4) As an example of the application of these equations, a pet food that is stored at -20°C, has a desired moisture content of 80% upon reconstitution with boiling water, and has a salt content of 1% at a food temperature of 30°C. Considering the case, the above equation requires the following condition. The moisture content can be reduced by (a) drying or (b) draining out the liquor. These different methods are illustrated in the examples below.

(a) For meat products with normal moisture content (75-80%), sufficient moisture has been removed to reduce the moisture content to 45-80%.
Cook or heat the meat until 50% cooked. After freezing, if the original product is to be recreated exactly, reconstitution is carried out by adding an amount of water equal to the amount of water that has evaporated, and if, for example, more sauce or gravy is desired than the amount of water that has evaporated. Restoration is carried out by adding more water than the amount of water.

Similar results can be obtained by starting from dried or dehydrated materials of fibrous tissue. For example, artificially shaped vegetable protein (TVP) or dried meat can be used as said substance. This material is partially rehydrated with some water-soluble salt containing water (H2O35-60% by weight) before freezing.

=17 shown.

Frozen product: Food solids Frozen water Unfrozen water Salt Rehydration: 100 parts frozen product at 20°C 111 parts water at 100°C Salts other than sodium chloride can be used, but the weight required for antifreeze effect is usually Higher than sodium chloride. For example, sodium monoglutamate may be added as a flavor enhancer instead of or in addition to sodium chloride. The amount of individual salt added is preferably between 0.5 and 4
% by weight, especially 0.5 to 2.5% by weight, and usually of the order of 2% by weight.

The production of the food product according to the invention requires that the moisture content of the raw material be adjusted before freezing.41.5% 47.9% 8.5% 2.1% Fibrous tissue It is surprising that the inclusion of a water-soluble salt component that becomes part of the unfrozen water within the pieces results in pieces that thaw and rehydrate in seconds upon contact with hot water. In a preferred embodiment, this partial watering is carried out in the meat component of the product (cooked), in which the appropriate amount of salt is dissolved.
This is done using For pieces that are very dry, rehydration will be very gradual, for pieces that are very wet or without added salt, thawing will not occur evenly, and if large amounts of salt are used, the process will be slow. is technically satisfactory, but the taste of the final product is unsatisfactory.

As an alternative to partially drying the food product by evaporating the water, a similar result can be obtained by contacting the food product with an absorbent material that removes the required amount of moisture from the food product.

This method can be used, for example, when the food product should not be subjected to the long cooking times necessary to evaporate the required amount of water from the food product.

(b) After cooking the meat, the required moisture content may be exceeded or the solids may be drained or squeezed out. The liquor is either discarded or absorbed into the dry material to increase the moisture content of the dry material to the same level as the processed meat.

During reconstitution according to the invention to make a food product edible, an amount of liquid is added to bring the product to an edible temperature and moisture content. The amount of added liquid to achieve a given diet temperature needs to be able to be determined within ±25% for gravy type meat products to provide an acceptable final product. It is difficult to expect housewives to measure the amount of liquid added to products at home.

A convenient method of metering the amount of rehydration fluid required for the product is a preferred feature of the invention. Place the product in a container and cover tightly with re-watering solution.

This operation can be easily determined visually. Production = 19 - expressed on a weight basis according to the amount of liquid required to reach a specific final temperature.

Salmon - 1 piece of meat scraps are shredded through a meat grinder plate, and 100 pieces
Cooked at ℃ for 10 minutes. The liquor from the heated butcher is cooked. The meat cutter was separated and pressed to remove more liquor and the water content of the pressed meat was about 50-60%.

95.2 parts of pressed meat were shredded with 2 parts of salt, 2 parts of carboxymethyl cellulose (CMC) and 0.8 parts of caramel. The ingredients were tightly pressed to a bulk density of 0.5 g/u and frozen in a domestic deep freezer at a temperature of -20°C.

The frozen product thawed and rehydrated within 30 seconds when mixed with enough boiling water to completely submerge the product, giving a final temperature of 33° C. and a moisture content of 75%. Such a reconstituted product consisted of meat in a thick gravy and had a shiny appearance. It can change the bulk density of the product very favorably for cats and dogs. Although there are other ways to measure the amount of rehydration fluid, this method appears to be the simplest.

The bulk density of the product can be varied or controlled in several ways.

(1) Squeeze the unfrozen product to achieve the correct density before freezing.

(2) Adjust the overall density by adding other ingredients with appropriate bulk densities.

(3) The material may be mechanically treated to reduce its density before freezing, for example by emulsification or foaming.

(4) The material may be mechanically treated during freezing, for example by whipping.

(5) The material may be mechanically treated to reduce bulk density after freezing, for example by comminution.

The invention will be explained in more detail by the following examples.

All parts and percentages were appropriate unless otherwise noted.

Example 2 Animal feed cooked shredded meat scraps were prepared as in Example 1 and pressed to remove excess liquor.

Add 93.2 parts of this to 2 parts of salt, 4 parts of pre-gelled starch powder (Instant Clear Gel; registered trademark) and 0.8 parts of caramel.
mixed with parts. This was prepared as in Example 1.

When the frozen product was rehydrated with just enough boiling water, a glossy looking product with a thick gravy and a temperature of 30° C. was finally obtained.

Example 3 Animal feed pressed meat was prepared as in Example 1. 95.8 parts of this were used along with 2 parts of salt, 0.8 part of locust bean, 0.6 part of xanthan and 0.8 part of caramel. This was prepared as in Example 1.

The thickening of the meat juice upon rewatering with boiling water was slower than in Examples 1 and 2, but within 1 minute a reconstituted product with a glossy gel at a temperature of 30° C. was obtained.

Example 4 Animal feed pressed meat was prepared as in Example 1 and 92.2 parts of this was
4 parts alginate (Manugel GHB; registered trademark), 1 part sicalcium phosphate, 2 parts salt and 0.8 parts caramel.
mixed with parts. Freeze this as in Example 1 and
A product with a dull gel when reconstituted was finally obtained.

Example 5 Animal Feed In this example, a crude pectin-containing material (citrus peel) is used as gelling agent. This pectin has been deesterified to have a degree of esterification of less than 20% (treated skin).

Pressed meat was prepared as in Example 1 and 92.2 parts of this were mixed with 4 parts of treated skin, 1 part of sicalcium phosphate, 2 parts of salt and 0.8 parts of caramel. When this was frozen as in Example 1 and reconstituted as in Example 1, a product with a dull gel was finally obtained.

□1 Dried Meat Salt Caramel MC Starch Locust Bean-I 95.2 93.2 95.8 92.2 92.2 (
part) 0.8 0.8 0.8 0.8 0.8
0.8 xanthan 0.6 Alginate-treated skin Calcium phosphate Instead of reducing moisture content by evaporation, Example 1 below
1 and 12, the addition of dry ingredients to reduce the overall moisture content is substituted.

Masu↓1-'111-meat scraps were cooked at <100°C for 10 minutes as described above. In these first five instances of meat, ingredients with lower moisture content were then cooked or discarded from the meat. Alternative methods of removing moisture from meat can be used to preserve this valuable by-product.

Examples 6 to 10 Animal feed meat meal was shredded through a 1σ mincer plate and cooked at 100° C. until the meat was almost free of glue. The meat was then placed on a tray in a heated air oven at 100°C until the moisture content was reduced to about 50%.

This step preserves the water-soluble components of the liquor while reducing the actual water content.

This dried meat was then processed in exactly the same way as the pressed meat of Examples 1 to 5 to give similarly favorable products (Table Finish Examples 6 to 10, respectively).

Cooked or mixed with car to reduce overall moisture content to 50%. Suitable compositions are: shredded meat potato protein biscuits VP fat cake, dried meat and bone meal aC Q tallow caramelized xanthan locust beans dried depigmented blood mixture is stirred during freezing or milled after freezing;
The formation of frozen pieces of hard-to-freeze solids should be prevented.

Example 12 Animal feed meat is cooked as in Example 1 and the cooked meat from this process is stored. 87 parts of this liquor were mixed with 13 parts of flour and the resulting dough was roll dried and ground into powder. This preserves the liquor and the flavor and nutrients of the liquor, and at the same time the starch of the flour gels, thus eliminating the need to add pre-gelled starch.

The final production of this example was carried out using 78.8 parts of cooked press with 19 parts of wheat rolled dry dough and cooked liquor, 2 parts of salt and 0.2 parts of caramel. This mixture was frozen according to Example 1.

Other suitable binders for cooked or cooked materials that can be incorporated prior to roll drying include soybean flour and gluten. However, when using these components, it is preferable to add a gelling agent at the end.

However, a particularly preferred embodiment of the invention can also combine the techniques of Examples 12 and 13, as shown in Example 14.

Example 14 Animal Feed In this example, a portion of the liquor from meat was used to produce TVP. The composition of the vegetable protein dough is as follows: Liquor 30 parts Defatted soy flour
60 parts Corn flour 10 parts Sulfur 0.02 parts The dough was extruded from a culinary extruder at 150°C. After cooling, the resulting TVP is combined with the remaining liquor;
A usable partially rehydrated TVP was obtained as in Example 13.

The principles of the invention are not limited to the production of animal feed. Example 15
It is also possible to produce human food, as exemplified in .

Based on the use of cooked or pressed carcasses of meat to partially re-water compatible TVP. This is illustrated in Example 13.

Example 13 Animal feed The meat was cooked and pressed as in Example 1.

Salt and caramel were dissolved in liquor. Equal weight dry TV
P was added to the liquor and the whole was stirred until the TVP took up the liquor. This partially rehydrated TVP is then
mixed with pressed meat. Salt and caramel were added to the frozen product at concentrations of 2% and 0.8%, respectively.

This mixture was then frozen as in Example 1 and upon thawing and rehydration yielded a chunky product with good appearance. The added liquid thaws the product by straining the liquor from the TVP.

However, if gravy production is required, press meat and TV
P can be coated with the thickeners of Examples 1 to 5 by simply stirring them together with the powder mixture.

Then, it was cooked at 100°C for 10 minutes. Liquor was pressed from the cooked meat as in Example 1 and to these was added salt and caramel as in Example 13. These liquors were then mixed with partially rehydrated TVP (Bondrea 240; registered trademark).
The product was then processed as in Example 13.

Upon rehydration, the product had a delicious beef aroma and, due to the structure of TVP, the product took on the appearance of chashu noodles. Furthermore, since Pontre is a highly absorbent form of TVP, even hotter liquid can be added to raise the eating temperature to 70-80°C.
It is possible to approach temperatures close to 0.degree. C. without producing excess gravy.

Another aspect of the invention is shown below.

1. A frozen food product comprising a frozen food or a food mixture, wherein the moisture content of the frozen food or mixture thereof is lower than the moisture content at the time of eating it, and which is easily permeable to thawing water; the product comprises frozen water and unfrozen water, and further includes one or more physiologically acceptable water-soluble salts in the food product in an amount sufficient to retain the unfrozen water;
The amount of each individual salt present is 4% by weight or less of the frozen product, and when two or more salts are present, the total amount thereof is 10% or less of the frozen product. frozen food products.

2. The frozen food product according to item 1 above, containing 0.5 to 4% by weight of individual salts.

3. Said second salt wherein the amount of the individual salts is substantially 2% by weight.
Frozen food products as described in Section.

4. The frozen food product according to any one of Items 1 to 3 above, wherein the salt is sodium chloride.

5. The frozen food product according to any of paragraphs 1 to 4, wherein the moisture content of the frozen food product is 30 to 80% of the original moisture content of the crude, unprocessed food.

6. Freezing the food with a low frozen food level according to item 5 above, wherein the water content of the frozen food product is 35 to 60% by weight of the original water content of the crude unprocessed food, and 2. A method of manufacturing a frozen food product comprising the step of manufacturing a frozen food product comprising unfrozen water and readily permeable to thawing water, wherein the added amount of salt retains the unfrozen water in the product. salts, but the individual salts should not exceed 4% by weight of the frozen product and, if more than one salt is present, their total amount should not exceed 10% by weight of the frozen product. A method for manufacturing a frozen food product featuring features.

11. The method according to item 10, wherein the moisture content of the frozen material is 30 to 80% by weight of the original moisture content.

12. The moisture content is 35 to 6 of the original moisture content.
12. The method according to item 11, wherein the amount is 0% by weight.

13. The method according to item 12, wherein the water content is 40 to 55% by weight of the original water content.

14. This product reduces the moisture content of fresh food.

7. The frozen food product of claim 5, wherein the moisture content of the frozen food product is 40 to 55% by weight of the original moisture content of the crude, unprocessed food.

8. The bulk density of the frozen product is such that the moisture content when the product is placed in a container and just covered with a rehydration liquid increases to the level of moisture content that the food would normally have when eaten. The frozen food product according to any one of items 1 to 7 above.

9. The frozen food product of claim 8, wherein the bulk density and water content of the frozen product are such that the rehydrated food is at dietary temperature when the rehydration liquid is at boiling point temperature.

10. Adjusting the moisture content of the food or food mixture to a level lower than the normal value of said food; incorporating at least one physiologically acceptable water-soluble salt into said food before, during or after said adjustment of the moisture content; and the method according to any one of Items 10 to 13, wherein the moisture content is adjusted using a moisture drainer containing the salt.

15. The method according to any one of items 10 to 13 above, wherein the moisture content is adjusted by a partially rehydratable dry food.

16. The method according to item 14, wherein the moisture content is reduced by drying the food.

17. The method according to item 16 above, wherein drying is performed by evaporating water from the food.

18. The method of claim 16, wherein the food product is contacted with an absorbent material to remove moisture from the product.

19. The method of claim 18, wherein the absorbent material is itself food and remains in the final product.

20. The method of item 14, wherein the water content is reduced by leaching water out of the food.

21. The method of claim 20, wherein the food is cooked and excess glue is drained or squeezed from the cooked food.

22, including the step of rehydrating the product by adjusting the bulk density of the product to the moisture content that the food would normally have when it is placed in a container and covered with a strong rehydrating solution. 21. The method according to item 20 above.

Claims (1)

[Scope of Claims] 1. A frozen food or a food mixture other than meat and vegetable protein is included, the water content of the frozen food or the mixture is lower than the water content when it is eaten, and thawing water is easily extracted. A permeable frozen food product, said food product comprising frozen water and unfrozen water, further comprising one or more physiologically acceptable water-soluble salts in the food product for retaining the unfrozen water. Although in sufficient quantities, the individual salts present should not exceed 4% by weight of the frozen product and, if two or more salts are present, their total amount should not exceed 10% by weight of the frozen product. A frozen food product characterized by comprising: 2. Frozen food product according to claim 1, containing 0.5 to 4% by weight of individual salts. 3. A frozen food product according to claim 2, wherein the amount of individual salts is substantially 2% by weight. 4. The frozen food product according to any one of claims 1 to 3, wherein the pre-air salt is sodium chloride. 5. The frozen food product according to any of claims 1 to 4, wherein the moisture content of the frozen food product is 30 to 80% of the original moisture content of the crude, unprocessed food. 6. The moisture content of the frozen food product is 35 to 60% by weight of the original moisture content of the crude, unprocessed food.
A frozen food product according to claim 5. 7. The moisture content of the frozen food product is 40 to 55% by weight of the original moisture content of the crude, unprocessed food.
A frozen food product according to claim 5. 8. The bulk density of the frozen product is such that the moisture content when the product is placed in a container and immediately covered with a rehydration solution increases to the level of moisture content that the food would normally have when eaten. A frozen food product according to any one of claims 1 to 7. 9. The bulk density and moisture content of the frozen product are such that the rehydrated food is at dietary temperature when the rehydration liquid is at boiling point temperature.
Frozen food products as described in Section. 10. Adjusting the moisture content of food or food mixtures other than meat and vegetable proteins to a level lower than the normal value of said food; before, during or after this adjustment of the moisture content, at least one physiologically acceptable water soluble incorporating a salt into the food product; and freezing the food product containing the salt and having a low moisture level to produce a frozen food product that includes frozen water and unfrozen water and is readily permeable to thawed water. a method of manufacturing a frozen food product comprising: the amount of salt added is at least sufficient to retain unfrozen water in the product, but the individual salts are no more than 4% by weight of the frozen product; A method for producing a frozen food product, characterized in that when two or more types of salt are present, the total amount thereof is 10% by weight or less of the frozen product. 11. The method according to claim 10, wherein the moisture content of the frozen material is 30 to 80% by weight of the original moisture content. 12. The moisture content is 35 to 60 of the original moisture content.
12. The method of claim 11, wherein the amount is % by weight. 13. The moisture content is 40 to 55 of the original moisture content.
13. The method of claim 12, wherein the amount is % by weight. 14. Claim 1, wherein the water content is adjusted by reducing the water content of fresh food.
The method according to any one of Items 0 to 13. 15. The method according to any one of claims 10 to 13, wherein the moisture content is adjusted by a partially rehydratable dry food. 16. The method of claim 14, wherein the moisture content of food is reduced by drying it. 17. The method according to claim 16, wherein the drying is performed by evaporating water from the food. 18. The method of claim 16, wherein the food product is contacted with an absorbent material to remove moisture from the product. 19. The method of claim 18, wherein the absorbent material is itself food and remains in the final product. 20. The method of claim 14, wherein the water content is reduced by leaching water out of the food. 21. Claim 2 for cooking food and draining or squeezing excess liquor from the cooked food
The method described in item 0. 22. A patent comprising a step of rehydrating the product by adjusting the bulk density of the product to the moisture content that the food would normally have when it is placed in a container and covered with a rehydrating liquid. The method according to claim 20.