CH639538A5 - FROZEN FOOD AND PROCESS FOR ITS PREPARATION. - Google Patents

Description

The invention presented herein relates to food products and their methods of preparation and use. The products can be intended for humans or animals. There is a considerable amount of prepared food available on the market that requires relatively little cooking or other processing to be ready for consumption. These products are usually referred to as minute products.

Known foods of this species usually fall into three categories: canned goods, dry products and frozen products. Each of these types of food, however, has their own problems and disadvantages.

35 The preserves are bulky and the quality of the product depends entirely on the good hermeticity of the box.

Dry products have a weak flavor. In particular, the consumer considers the dry products to be rehydrated to be of low quality and little flavor, and many problems are still to be overcome. Much work has been done to find ways to retain flavor, aroma and texture by reducing the denaturing effects of heat and solute concentration. Although success has been recorded in the laboratory for certain products, major problems appear during the transition to the industrial scale. Although the sale of frozen products has increased rapidly in the past fifteen years, and more particularly in the past five years, in parallel with the acquisition of domestic freezers, there are still problems of use.

The current frozen food market can be divided into three sectors:

1) Frozen uncooked foods such as blanched vegetables, fish cakes and hamburgers that do not need to be thawed before cooking. However, they need to be cooked

55 and, since they must not be thawed before, they must necessarily be in small pieces or have a large contact surface, such as the food to be cooked in the package. The preparation and cooking times vary between 5 and 25 min.

2) Whole frozen uncooked foods such as whole chickens or pieces of meat. These products must be thawed before cooking and the total preparation time may exceed 24 hours.

3) Cooked foods ready to be eaten such as frozen whole meals and roasted meat slices. These need to be heated for more than 10 min in a traditional oven or

65 then in a more expensive way, in a microwave oven.

All these products have the same major disadvantages, they all need to thaw and / or cook before reaching an appropriate stage for consumption.

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Besides the use of freezing to preserve food, there is a freezing process to obtain concentrated products. The ice formed during the freezing of a liquid product can be removed from this product, for example a fruit juice, which gives a product with a low water content, which can be reconstituted later. The extreme case is the elimination of most of the ice, lyophilization, which gives instant rehydratable products, for example soluble coffee.

An essential limitation of the concentration by freezing is the fact that it only applies to liquids. Lyophilization can be applied to solids and liquids, but the products obtained are intended to be stable under ambient conditions and, although the reconstitution is rapid, such products which include solid parts do not have a flavor or a acceptable texture.

An object of the invention presented here consists in providing foods which can be stored and which can quickly and easily be brought under conditions suitable for their consumption and which have acceptable or advantageous organoleptic properties.

This invention provides a frozen food product which is easily penetrated by thaw water and which contains a food or mixture of foods which has a lower water content than that food or mixture of foods normally has when '' it is ready to be consumed, this food or mixture containing at the same time frozen and not frozen water and also containing at least one water-soluble salt which is physiologically acceptable, in an amount sufficient to maintain non-frozen water in the product but which does not exceed 4% by weight, based on the weight of the frozen product for an individual salt, and which does not exceed a total of 10% by weight compared to the frozen product when using several salts.

The product of this invention can be reconstituted by the addition of hot or boiling water in an amount such that the water content of the product is restored to its normal value, and at the same time the temperature of the product is brought to that of its consumption. .

This invention also provides a method of making this frozen food product, which comprises adjusting the water content of a food or mixture of foods below its normal value and incorporating, before, during or after said adjusting the water content, at least one physiologically acceptable hydrosoluble salt, then freezing the food depleted in water and which contains said salt, said salt being added in an amount at least sufficient to ensure the presence of unfrozen water in the product but which does not exceed 4% by weight of the frozen product for an individual salt and which does not exceed a total of 10% by weight of the frozen product when several salts are present.

The water content of the food is preferably reduced to a value of 30 to 80%, advantageously from 35 to 60% and at best from 40 to 55% of the original value of water content of the raw and unprocessed food.

The adjustment of the water content can be carried out by removing water from the fresh food, or by partial rehydration of a dry and possibly powdered food.

The latter process can be used, for example, to create reconstituted products from textured vegetable proteins that look like meat.

The products obtained according to this invention can combine the flavor and texture of frozen food with the ease of preparation of food to be rehydrated. It is possible and highly recommended to obtain thaw and rehydration in a few seconds, in any case in a few minutes.

To obtain the best results, there are three important factors to consider.

Firstly, the frozen product must be porous or easily penetrable so that both thawing and rehydration are rapid and homogeneous. This can be achieved either by making a product from small particles, or by appropriate treatment of larger pieces to obtain a certain texture. An important feature of this invention is the discovery that pieces of food can be used in this product and that,

if treated properly, they can also thaw and rehydrate quickly.

Second, the initial water content is adjusted so that when an appropriate amount of high temperature water is added to the frozen product to bring it to consumption temperature, the water content of the final product is approximately that which the 'we would wait in the unfrozen product. This condition does not establish a fixed limit for the relative quantity or for the temperature of the water added during the thaw / rehydration stage. These two factors depend entirely on the type of product. A meat product can be formulated to be consumed between 20 and 40 ° C by animals or, by reducing its initial water content, increasing the volume of water added or increasing the temperature of the added liquid, to be consumed between 50 and 70 ° C by humans. It is the total amount of heat (water temperature x volume) that is important.

Third, a portion of the product's water should remain unfrozen. This proportion is controlled by the water-soluble salt which is part of the product. The aqueous phase of a solution of a given solute in contact with ice and in equilibrium always has the same concentration. Therefore, the more salt added, which is usually sodium chloride, the more water is needed to dissolve it (water that will remain unfrozen) at a given temperature below freezing. Control of the quantity of frozen water is critical for obtaining the final temperature of the product since the latent heat of fusion of the ice is 80 cal / g, while the specific heat of the water is 1 cal / g. Eight times more heat is drawn from the water added to melt each gram of ice than to raise the temperature of each gram of melted ice by 1 °. The consumption temperature of the product can therefore be controlled by this ratio of frozen water / non-frozen water in the product. It is possible to calculate a relationship between water content, soluble solids content and the amount and temperature of water added for a product, which gives a desired consumption temperature and a concentration.

For example, when the frozen product consists of a grams of unfrozen water (containing a small amount of soluble solid food), b grams of frozen water and c grams of solid food and which is at a temperature of - K ° C, and that it must be brought to the temperature of + P ° C and to a final water content of W% by the addition of d grams of water at the initial temperature of + T ° C, then taking the specific heat of water equal to 1, that of ice equal to 0.3 and that of solid food equal to 0.8, and the latent heat of fusion of ice equal to 80 cal / g, we have:

a (K + P) + b (0.3K + 80 + P) + 0.8c (K + P) = d (T - P) (1)

Assuming that the final reconstituted product must contain 1% sodium chloride (a typical value), which is provided by the salt content of the frozen product, and keeping in mind that the concentration of a chloride solution sodium in equilibrium with ice at -20 ° C is about 20%, then:

a = 0.04 (a + b + c + d) (3)

Finally, when the result must be expressed in percent:

a + b + c = 100 (4)

As an example of application of these equations, we take the case of a pet food stored at -20 ° C and which must be reconstituted with boiling water to provide a water content of 80% and a content of 1% salt at a consumption temperature of 30 '"C, the above equations indicate the following conditions:

s

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4

Frozen product: solid food 41.5%

frozen water 47.9% non-frozen water 8.5% salt 2.1%

Rehydration: frozen product at —20 ° C 100 parts water at 100 ° C 111 parts

Salts other than sodium chloride can be used, but the weight required to achieve the same antifreeze effect is generally greater. Monosodium glutamate can be added as a flavor enhancer, in place of or in addition to sodium chloride. The amount of each salt taken individually which is added varies between 0.5 and 4%, and especially between 0.5 and 2.5% by weight relative to the frozen product and is generally 2% by weight.

The manufacture of a food product according to this invention requires that the water content of the food be adjusted before freezing. The reduction of the water content can be obtained: a) by drying, or b) by drawing off the juice. These different techniques can be illustrated by the following examples taken from practice.

a) For a meat product with a normal water content (75-80%), the meat is cooked or heated until enough water has been removed to give a water content of 45-50%. After freezing, the reconstitution is obtained by adding an amount of water equivalent to that which has evaporated, in the case where the original product has to be reconstituted exactly, or in a larger amount if, for example, we want an additional amount of sauce.

A similar result can be obtained from dry or dehydrated material having a fibrous texture, for example textured vegetable protein (TVP) or dried meat, which can be used in this application. This material is partially rehydrated (up to 35 to 60% by weight of H2O) with water which contains a water-soluble salt, before freezing. The fibrous texture and the inclusion of a water-soluble salt, which causes the presence of unfrozen water in the pieces, combine surprisingly to give pieces that thaw and rehydrate in a matter of seconds when they are in contact with boiling water.

According to a preferred packaging, this partial rehydration is carried out using the juices of the cooked pieces of meat which form part of the product, in which the appropriate amount of salt has been dissolved. For pieces that are too dry, rehydration takes place too slowly; when they are too wet or without the addition of salt, the thaw is not uniform; with larger amounts of salt, the process is technically satisfactory,

but the taste of the final product may be unsatisfactory.

As an alternative to partial drying of a food product by evaporation, it is possible to obtain a similar result by contacting the food product with an absorbent material which will remove the necessary amount of water from the food product.

This method can be used for example when the food product should not be cooked for the period which may be required to evaporate a sufficient amount of water from the product.

b) After the meat is cooked, you can extract or express the excess juice that is too much of the required water content. The juice can be discarded or absorbed by a dry product so that the water content of the dry product is raised to the level of the content of the pressed or drained meat. When reconstituting the food products of this invention to bring them into a state suitable for consumption, an amount of liquid must be added to bring the product to a temperature and to a water content suitable for consumption. For a given tasting temperature, we must assess the amount of liquid added to within + 25% to obtain an acceptable final product, that for meat products accompanied by sauce. In a domestic situation, the housewife is not expected to weigh the liquid based on the product.

One of the features of this invention is a convenient way to measure the amount of liquid needed to rehydrate this product. The material is boxed and it is just covered with rehydration fluid. It can simply be judged by eye.

For simplicity, the overall density of the product can be adjusted according to the quantity of liquid necessary to obtain a given final temperature and composition.

Although there are other ways to measure the amount of rehydrating fluid, this appears to be the most practical. The overall density of the product can be changed or controlled in several ways:

1) The pre-frozen product can be pressed until the correct density is obtained, before freezing.

2) Other materials of appropriate overall density can be added to adjust the density of the whole.

3) The material can be treated mechanically so as to decrease its density before freezing, for example by emulsifying or foaming it.

4) The material can be processed mechanically during freezing, for example by whipping it.

5) The material can be processed mechanically after freezing, for example by reducing the density by grinding.

The following examples are given for illustration only. All parts and percentages are given by weight, unless the context indicates otherwise.

Example 1 Animal feed

Meat offal is minced to a thickness of 1 cm and is cooked at 100 ° C for 10 min. During cooking, the juice comes out of the meat. The meat is separated from the juice and is expressed to remove more juice so that the water content of the expressed meat is about 50-60%.

95.2 parts of meat expressed with 2 parts of salt, 2 parts of carboxymethylcellulose (CMC) and 0.8 part of caramel are minced. The ingredients are pressed tightly to give an overall density of about 0.5 g / ml, then they are frozen at -20 ° C in a household freezer.

This frozen product, when mixed with just enough water to cover it, thaws and rehydrates in 30 s to give a final temperature of 33 ° C and a water content of 75%. The reconstituted product consists of meat surrounded by thick sauce and which has a shiny appearance. It is very well received by dogs and cats.

EXAMPLE 2 Animal Food

Minced and cooked meat offal are prepared as in Example 1 and expressed to remove the excess juice. 93.2 parts are mixed with 2 parts of salt, 4 parts of starch which is already in the form of gelatin (Instant Cleargel, registered trademark) and 0.8 parts of caramel. This was prepared as in Example 1.

When rehydrating with just enough boiling water to cover the frozen product, this formula produces a product with thick, shiny-looking sauce at a temperature of 30 ° C.

EXAMPLE 3 Animal Feed

Expressed meat is prepared as in Example 1. 95.8 parts of it are used with 2 parts of salt, 0.8 part of carob, 0.6 part of xanthan and 0.8 part of caramel. This is prepared as in Example 1.

By rehydration with boiling water, the thickening of the sauce is slower than in Examples 1 and 2 but, within 1 min, a product is obtained covered with a brilliant gel which is at a temperature 30 ° C.

EXAMPLE 4 Animal Feed

Expressed meat is prepared as in Example 1 and 92.2 parts are mixed with 4 parts of alginate (Manugel GHB, registered trademark), 1 part of dicalcium phosphate, 2 parts of salt and

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0.8 parts of caramel. This is frozen as in Example 1 and, when reconstituted as in Example 1, a product covered with a matt gel is obtained.

EXAMPLE 5 Animal Feed

This example uses as a gelling agent a material based on crude pectin (lemon peel), the pectin content of which has been de-esterified to a degree of esterification of less than 20% (treated peel).

Expressed meat is prepared as in Example 1 and 92.2 parts of it are mixed with 4 parts of treated skin, 1 part of dicalcium phosphate, 2 parts of salt and 0.8 part of caramel. This is frozen as in Example 1 and, when reconstituted as in Example 1, the final product is covered with a mat gel.

These first five examples involve the rejection of the cooking juices from the meat. As a first step to preserving this precious side product, another method of removing water from the meat can be used.

EXAMPLES 6 TO 10 Animal feed

Meat offal is minced to a thickness of 1 cm and cooked at 100 ° C until most of the meat juice is reduced. This meat is then placed in a hot air oven at 100 ° C on a plate and left until the water content has decreased by about 50%. This process retains the water-soluble components of the cooking juice and, at the same time, the water content is reduced.

This dried meat can then be treated in exactly the same way as the meat expressed in Examples 1 to 5 (Examples 6 to 10 respectively in Table I) to give similarly acceptable products.

Table I

Example

6

7

8

9

10

(parts)

Dried meat

95.2

93.2

95.8

92.2

92.2

Salt

2

2

2

2

2

Caramel

0.8

0.8

0.8

0.8

0.8

CMC

2

-

-

-

-

Starch

-

4

-

-

-

Carob

-

-

0.8

-

-

Xanthan

-

-

0.6

-

-

Alginate

-

-

-

4

-

Processed peel

-

-

-

-

4

Dicalcium phosphate

-

-

-

1

1

Instead of reducing the water content by evaporation, one can alternatively add dry ingredients which reduce the overall water content, as described in Examples 11 and 12.

EXAMPLE 11 Animal Feed

The previous meat offal is cooked at 100 ° C for 10 min. Ingredients are then mixed with low water content with the cooking juices so as to reduce the total water content to 50% of its value. An appropriate formulation is:

Minced meat 55 parts

Potato protein 5 parts

5 part cookie

5 parts TVP

Rillons, dry 10 parts

Meat and marrow 5 parts

NaCl 2 parts

Tallow 3 parts

Caramel 0.1 part

Xanthan 0.6 part

Carob 0.8 part

Discolored dry blood 8.5 parts

This mixture should be stirred during freezing or ground after freezing to avoid the formation of frozen solid pieces that will not easily thaw.

EXAMPLE 12 Animal Feed

Meat is cooked as in Example 1 and the cooking juices are collected. 87 parts of these juices are mixed with 13 parts of wheat flour, and the dough obtained is dried in a drum and ground into powder. By this means, the juices and their flavor and nutrients are spared and, at the same time, the flour starch is gelled, which avoids having to add to the final formula of pregelified starch.

The final formulation of this example consists of 78.8 parts of cooked expressed meat, 19 parts of flour dough and meat juices, which have been tumbled, 2 parts of salt and 0.2 part of caramel. This mixture is frozen according to the instructions of Example 1.

Other binding agents for cooking juices, which may be included before tumble drying, include soy flour and gluten. However, the addition of a gelling agent in the final formula is recommended when using these ingredients.

A particularly preferred packaging is based on the use of cooking juice to partially rehydrate TVP. This is described in Example 13.

EXAMPLE 13 Animal Feed

Meat was pressed and cooked as in Example 1. Salt and caramel are dissolved in the cooking juices. An equivalent weight of dry TVP is added to the juice and stirred until the TVP absorbs the liquid. This partially rehydrates the TVP, which is then mixed with the expressed meat. An amount of salt and caramel is added such that a concentration of 2% and 0.8% respectively is obtained in the frozen product.

This mixture can then be frozen as in Example 1 and, during thawing and rehydration, pieces of good appearance are obtained. The cooking juice comes out of the TVP when adding the liquid which is used to thaw the product. However, if a sauce is desired, the expressed meat and the TVP can be covered with a thickening agent as in Examples 1 to 5 by simple agitation with a powder of these agents. It is also possible to combine the methods of Examples 12 and 13 as described in Example 14.

EXAMPLE 14 Animal Feed

In this case, part of the cooking juices drawn from the meat is used to prepare the TVP. A vegetable protein paste formula is as follows:

Cooking juices 30 parts

Degreased soy flour 60 parts

Corn flour 10 parts

Sulfur 0.02 part

This paste is extruded at 150 ° C in a suitable apparatus. After cooling, the resulting TVP is combined with the rest of the cooking juices to give partially rehydrated TVP which can be used as in Example 13.

The principles of this invention are not limited to the preparation of animal feed. It is also possible to make a food for humans as described in Example 15.

EXAMPLE 15 Food for Humans

Braising steak is minced to a thickness of 1 cm and cooked to

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100 ° C for 10 min. The juice is expressed from cooked meat as in Example 1 and salt and caramel are added to it as in Example 13. These juices are used to partially rehydrate TVP (Bontrae 7240, registered trademark), then the product is treated as in Example 13. During rehydration, the product 5

has a pleasant beef aroma and looks like Chow Mein because of the texture of the TVP. In addition, since Bontrae is a very absorbent form of DVT, more boiling liquid can be added so that the temperature is around 70 to 80 ° C, without having an excess of sauce.

Claims (22)

639,538 2 1. Frozen food product which can be easily penetrated by thawing water, characterized by the presence of a food or a mixture of foods, this food or mixture of foods having a water content lower than that which is normally present in these foods during their consumption, this water being present in the frozen and unfrozen state, as well as at least one physiologically acceptable water-soluble salt, in an amount sufficient to maintain part of the water in the not frozen state, but not exceeding 4% by weight of the food product for an individual salt and not exceeding a total of 10% by weight of the food product when several salts are present. 2. Frozen food product according to claim 1, characterized by the presence of 0.5 to 4% by weight of an individual salt. 3. frozen food product according to claim 2, characterized in that the amount of salt is 2% by weight. 4. Frozen food product according to one of claims 1 to 3, characterized in that the salt is sodium chloride. 5. Frozen food product according to one of claims 1 to 4, characterized in that the water content is 30 to 80% of the original content of the raw and untreated food (s). 6. Frozen food product according to claim 5, characterized in that the water content is 35 to 60% of the original content of the raw and untreated food (s). 7. Frozen food product according to claim 5, characterized in that the water content is 40 to 55% of the original content of the raw and untreated food (s). 8. Frozen food product according to one of claims 1 to 7, characterized in that its apparent density is such that, when placed in a box and just covered with a rehydration liquid, the water content is brought to the normal level when the food is ready for consumption. 9. Frozen food product according to claim 8, characterized in that the apparent density and the water content of the product are such that, when the rehydration liquid reaches its boiling point, the rehydrated food is at its temperature of consumption. 10. Method for preparing a frozen food product according to claim 1, characterized in that the water content of the food or the food mixture is adjusted to a level which is lower than its normal value, that one incorporates in the food or foods, before, during or after the adjustment of the water content, at least one water-soluble and physiologically acceptable salt, then that one freezes said food depleted in water and which contains the salt , said salt being added in an amount at least sufficient to ensure the presence of non-frozen water in the product, but which does not exceed 4% by weight of the frozen food product for an individual salt and which does not exceed a total of 10 % by weight of the frozen food product when several salts are present. 11. Method according to claim 10, characterized in that the water content is adjusted to a value of 30 to 80% of the original content. 12. Method according to claim 11, characterized in that the water content is adjusted to a value of 35 to 60% of the original content. 13. Method according to claim 12, characterized in that the water content is adjusted to a value of 40 to 55% of the original content. 14. Method according to one of claims 10 to 13, characterized in that said adjustment of the water content is obtained by a reduction in the water content of the fresh food or foods. 15. Method according to one of claims 10 to 13, characterized in that the adjustment of the water content is obtained by partial rehydration of the dry food or foods. 16. Method according to claim 14, characterized in that the water content is reduced by drying the food or foods. 17. Method according to claim 16, characterized in that the drying is carried out by evaporating the water from the food or foods. 18. Method according to claim 16, characterized in that the drying is carried out by bringing the food (s) into contact with 5 a material which absorbs water from food (s). 19. The method of claim 18, characterized in that the absorbent material is itself a food and that it remains in the final product. 20. The method of claim 14, characterized in that the water content is reduced by drainage of the water from the food (s). 21. The method of claim 20, characterized in that one or more food is cooked and that one draws or squeezes the excess juice from the cooked food or foods. 22. Method according to one of claims 10 to 21, characterized in that the apparent density of the product is adjusted so that, when it is placed in a box and that it is just covered with liquid rehydration, the product rehydrates to a water content which corresponds to that which is normally present in the food when it is ready to be consumed.