JP2000228961A - Freeze-dried soybean-curd and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain freeze-dried soybean-curd enabling the character of silk- strained soybean-curd to be favorably reproduced by being reconstituted with water or hot water by freeze-drying treatment of soybean-curd without causing freeze denaturation. SOLUTION: This freeze-dried soybean-curd is obtained by the following process: starch and collagen peptide are mixed into soybean milk, a coagulant for soybean-curd is added to the resulting mixture followed by heating to a temperature higher than the temperature being higher one, starch gelatinization temperature or coagulant reaction temperature, and then cooling; the resulting system is frozen and then freeze-dried.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention enables freeze-drying of tofu, which is considered difficult to freeze, and reproduces the properties of ordinary silk tofu by freeze-drying and then returning it with hot or cold water. Freeze-dried tofu and a method for producing the same.

[0002]

2. Description of the Related Art Tofu has long been used in Japan as a food rich in high-quality protein and is one of the essential foods. However, the storage stability is poor due to the high water content. Generally, there is drying as a method for imparting preservability to food. Nowadays, freeze-drying is used as an effective drying method capable of minimizing loss of physical properties and components of food, and many food ingredients are freeze-dried and distributed on the market as instant foods. However, when freeze-dried tofu, even if the product is rehydrated with water, it has completely different physical properties from the tofu before freeze-drying. This is because, during freezing, which is usually performed in freeze-drying, ice crystals grow in a network of tofu protein molecules that form a tofu gel, thereby causing the protein molecules to approach and cause intermolecular bonding to form a sponge-like tissue. It can be explained that the freeze-dried product eventually becomes a sponge-like tissue due to freeze denaturation. In addition, when the self-freezing method is employed for freeze-drying, if the amount of tofu charged is reduced and the load on the cold trap during vacuum drawing is reduced, freezing can be performed quickly and freezing denaturation can be prevented. However, it is well known that such a method requires a large drying cost and is not suitable for practical use.

[0003] By making freeze-resistant tofu to prevent freeze denaturation during freezing before freeze-drying,
Methods have been developed to prevent sponge-like organization after freeze-drying.However, freeze-dried tofu found on the market today is disadvantageous in that it has an undesired texture due to auxiliary ingredients added to prevent freezing and denaturation. This is probably why consumers do not like it. In addition, the properties of the auxiliary materials make the manufacturing process difficult.

Japanese Patent Application Laid-Open No. 5-184321 discloses that tofu is prepared by mixing 1.0 to 1.5 parts by weight of a gelling agent and starch with soymilk and coagulating by heating with a soymilk coagulant. A method of freeze-drying is disclosed. This method gels and fixes the components and water in the tofu with a gelling agent, suppresses intermolecular bonding of the tofu protein molecules during freezing, prevents freezing denaturation, and makes the tissue after freeze drying not spongy. It is considered something. However, in this method, when the tofu after freeze-drying is returned with hot water or water, a texture other than the tofu protein gel is present in the tofu tissue, so the texture differs from the original tofu, and the texture of the gelling agent used is different. Was presented. In addition, since a gelling agent is used, the cooling temperature before heat coagulation is limited to 20 to 40 ° C.,
It is expected that management after adding the coagulant is difficult. In other words, under low temperature conditions, the thickener is caused by the reaction of the gelling agent, and conversely, when the temperature is high, the thickening is caused by the coagulant reaction,
It can easily be inferred that the subsequent operations such as filling will be hindered. In addition, although it is heated and coagulated, holding in such a temperature range should be avoided from the viewpoint of food hygiene.

[0005]

The present invention solves at least one of the above-mentioned problems. It enables freeze-drying of tofu that has been difficult to freeze until now.
The purpose is to produce freeze-dried tofu that can sufficiently cool and preserve the liquid before heat coagulation and can reproduce the texture and flavor very similar to ordinary silk tofu by returning the product with hot water or water. .

[0006]

Means for Solving the Problems The present inventors have intensively studied to solve the above-mentioned problems. As a result, by using the collagen peptide together with the starch, freeze-drying can be performed without freeze denaturation,
It has been found that the properties of silk tofu can be satisfactorily reproduced by returning with hot water or water. The present invention has been completed based on such findings.

That is, according to the present invention, a starch and a collagen peptide are mixed in soy milk, and a coagulant for tofu is added thereto,
Heating to a temperature higher than the higher of the starch gelatinization temperature and the coagulant reaction temperature to coagulate and freeze, then keep this at a low temperature below the freezing point in a vacuum, remove water by sublimation and dry. A freeze-dried tofu characterized by the following features:

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, soymilk refers to soymilk and soybean protein powder prepared by a conventional method or those prepared from powdered soymilk, and other food materials (eg, hijiki, shiitake, etc.) ) And flavors (e.g., matcha, sesame, yuzu, etc.), including soymilk having a solid content of 5 to 20%, and more preferably 1 to 5% by solid content, prepared by a conventional method.
Soy milk of 0 to 15%, and soy milk of 13% solid content is most preferable for improving the flavor and texture of the final product.

In the present invention, the starch may be any starch that can be used for food, such as natural products such as potato, corn starch, tapioca, and processed products thereof. Among them, potato starch that has been etherified is excellent in freezing resistance and aging resistance, and is most preferable in order to achieve the object of the present invention of gelatinizing a solution in a tofu tissue and preventing freezing denaturation of tofu. The amount used is 0.1 to 10 parts by weight, based on 100 parts by weight of soy milk,
It is more preferable to use 1 to 5 parts by weight, and 2 to 3 parts by weight to minimize the influence on the texture and flavor of the product and to achieve the object of the present invention.

The collagen peptide referred to in the present invention is gelatin or a gelatin raw material having a molecular weight distribution of 5,000 to 50,000 in which gelation ability has been eliminated by enzymatic treatment with a protease or other treatment. It is soluble in cold water, unlike gelatin. Preferably, those having a molecular weight distribution of 5,000 to 20,000 have the least effect on viscosity even after being dissolved in soy milk, and are most preferred in order to achieve the object of the present invention of preventing freezing denaturation of tofu. The amount to be used is 0.1 to 100 parts by weight of soymilk.
Although it is in the range of 0.01 to 5 parts by weight, it can be said that it is sufficient to use 0.5 to 1 part by weight in order to obtain the desired effect of the present invention.

The tofu coagulant referred to in the present invention may be any of magnesium chloride, calcium sulfate, glucono-delta-lactone, a preparation obtained by mixing these, and any other coagulant for tofu. Good. Among them, glucono delta lactone is most preferable in that it is easy to control the temperature after the addition of the coagulant and that it forms a uniform and smooth tofu gel by heating. The amount to be used is 1% soymilk 13% solid as in the case of ordinary silk tofu production.
It is desirable to use about 0.3 parts by weight with respect to 00 parts by weight. Heating for coagulation may be performed by filling a desired container such as a filled tofu container or a coagulation can. The heating condition may be a temperature equal to or higher than the higher of the starch gelatinization temperature and the coagulant reaction temperature. Specifically, the product temperature is 75 to 90
C. for 15 to 30 minutes, preferably at 85.degree. C. for 20 minutes.

The thus obtained tofu is freeze-dried by a conventional method, but it is preferable that the tofu be cooled once, cut to a desired size and then frozen in order to make the frozen tissue uniform. Freezing may be by self-freezing in a vacuum dryer, but as mentioned above, as a practical method taking production costs into account, it is realistic to freeze tofu separately from freeze drying. . In this case, depending on the amount of tofu, -2
If there is a sufficient air flow at 0 ° C. or less, it is possible to freeze with a good tissue. The shelf heating temperature during freeze drying is 40
~ 70 ° C is desirable, but at the time of tofu loading, the shelf is cooled and vacuum drawing is started, and when the degree of vacuum reaches about 0.1 torr, the shelf heating temperature is set to about 60 ° C. It is more preferable to drop the temperature to about 40 ° C. and terminate the drying when the temperature becomes stable at about 0.02 torr.
This means that while ice crystals are present in the food, heat is consumed in the sublimation, but as the ice crystals disappear, the food temperature rises, and in the case of tofu, it causes yellowing and oxidation of ingredients Because.

In producing the freeze-dried tofu of the present invention, a vegetable gum may be added together with the collagen peptide. Any vegetable gum may be used as long as it is used for food, but tamarind gum, guar gum, those having no gelling ability such as tragacanth gum are desirable, and those soluble in cold water are more preferable. preferable.
It is necessary to use an appropriate amount for each kind of gum depending on the viscosity applied to soymilk. The use of the vegetable gum makes it possible to more stably maintain the size liquid in the tofu tissue, further suppress the growth of ice crystals, and make the tissue after freeze-drying more fine.

In producing the freeze-dried tofu of the present invention, vegetable fats and oils may be further added. In this case, vegetable gum may or may not be used. Vegetable oils and fats may be any edible vegetable oils such as soybean oil, rapeseed oil, corn oil, safflower oil, peanut oil, sesame oil and coconut oil. Among them, soybean oil is the most preferable in achieving the object of the present invention, which imparts a tofu-like richness to the product and suppresses the appearance of flavor such as starch. By using 0.1 to 10 parts by weight, preferably 3 to 5 parts by weight, per 100 parts by weight of soymilk, natural richness is given to tofu, and it becomes possible to suppress the appearance of flavor such as starch.

Further, it is desirable to use an emulsifier in order to completely mix the oil and fat in the soymilk. The emulsifier may be any as long as it is used in food production, but soy lecithin is most preferred because it does not affect the flavor of tofu. This makes it possible to prevent the release of fats and oils after freeze drying.

[0016]

[Examples] Examples of the production of frozen tofu of the present invention are described below in Example 1.
And Comparative Example 1 in which a gel-type water-dispersible granulated gelatin having improved solubility in water was used instead of collagen peptide, and Comparative Example 2 in which soy milk was coagulated only with a coagulant In addition to the description of the production method, the viscosity before the addition of the coagulant in the production process, the state of the freeze-dried product, and the sensory evaluation results when the product is returned by adding hot water at 90 ° C. are described. However,
The present invention is not limited by these Examples and Comparative Examples.

[0017]

Example 1 Kure was heated and squeezed by a conventional method to prepare soymilk having a solid content of 13% and cooled to room temperature. The reason for setting the temperature at normal temperature is to prevent gelatinization from occurring during starch mixing. Separately, 3.2 g of soy lecithin was dissolved in 430 g of soybean oil. Add 10 kg of soy milk to etherified potato starch 270
g, 65 g of collagen peptide having a molecular weight distribution of 5,000 to 20,000, 11 g of cold water-soluble tamarind gum, and the entire amount of soybean oil were added and mixed with a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). This is called a soymilk preparation. The soymilk preparation was cooled to 10 ° C. or lower, and 0.28% by weight of glucono delta lactone was dissolved in 4 times the weight of water with respect to the soymilk preparation, and added and mixed. This was poured into a coagulation can, and after reaching a product temperature of 85 ° C. in hot water of 90 ° C., it was heated for 20 minutes to coagulate and then cooled to room temperature. Take this out of the container and cut it on a tray with 2 layers of 1 cm square,
The mixture was frozen in an atmosphere of -20 ° C for 2 hours, loaded into a vacuum freeze dryer cooled to a shelf temperature of -10 ° C, and vacuum drawing was started.
Thereafter, heating was started at a shelf temperature of 60 ° C. at a degree of vacuum of 0.1 torr, and the shelf temperature was lowered to 40 ° C. at 0.03 torr.
Drying was completed at 0.02 torr to obtain freeze-dried tofu.

[0018]

Comparative Example 1 A gel-type water-dispersible granulated gelatin having a molecular weight distribution of 100,000 to 300,000 (main peak 100,000) and improved water solubility was used in place of collagen peptide based on Example 1. The tofu was prepared in the same manner as in Example 1, except that the temperature of the soy milk was set to 40 ° C. in order to dissolve the water-dispersible granulated gelatin. I got tofu.

[0019]

[Control group 2] Soy milk having a solid content of 13% was prepared in the same manner as in Example 1, cooled to 10 ° C or less, and 0.3% by weight based on the soy milk.
Of glucono delta lactone was dissolved in 4 times the weight of water and added and mixed. Thereafter, tofu was prepared in the same manner as in Example 1 to obtain freeze-dried tofu.

Table 1 shows the viscosities of the soymilk preparations and the state at the time of filling in Example 1 and Comparative Examples.

[0021]

[Table 1]

As shown in Table 1, in Example 1 and Comparative Example 2, the liquid was completely maintained even when cooled to 8 ° C., and there was no problem in filling the container. (Using gelatin) at 10 ° C., it was barely fluid, but bubbles generated during filling of the container did not float, it was very difficult to fill, and much liquid remained during filling.
Next, the appearance of the freeze-dried product is shown in Table 2.

[0023]

[Table 2]

As shown in Table 2, in Example 1 and Comparative Example 1, there was no particular problem in appearance, and the structure was white and dense. A coarse sponge-like structure was obtained. Next, the results of sensory evaluation in the case where hot water of 90 ° C. was added to the product and returned was described.

[0025]

[Table 3]

As shown in Table 3, in the sensory evaluation after hot water replenishment, the evaluation was high in both texture and flavor in Example 1, whereas
Comparative Example 1 was inferior in evaluation due to reasons such as being hard and difficult to sense the flavor, and Comparative Example 2 resulted in very poor texture and flavor due to completely different physical properties.

[0027]

The present invention is embodied in the form described above and has the following effects. That is, by adding starch and collagen peptide to soy milk, which is a tofu raw material, the aqueous solution in the tofu tissue after heat coagulation is gelatinized with starch, and the paste liquid in the tofu tissue is stably maintained by the collagen peptide to freeze. The growth of ice crystals can be prevented. In addition, since the collagen peptide does not have a gelling ability, it is possible to sufficiently cool the soymilk solution which has been prepared until it is heated and coagulated, so that operations such as temperature control and filling are easy. In addition, it can be stored in a safe state from the viewpoint of hygiene management in the manufacturing process. Then, by adding the vegetable gum to the soymilk, the size liquid in the tofu tissue can be further stably maintained, and the effect of suppressing the growth of ice crystals can be further enhanced. Further, by adding vegetable oils and fats to soymilk, the product is given a rich body, and the expression of flavor such as starch can be sufficiently suppressed.

As a result of these combined actions, freeze-dried tofu which can be freeze-dried without freezing denaturation and which can reproduce the properties of silk tofu satisfactorily by returning with hot water or water can be easily obtained. It has become possible to manufacture.

[Brief description of the drawings]

FIG. 1 is a process chart of Example 1 of the present invention.

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[Procedure amendment]

[Submission date] November 30, 1999 (1999.11.
30)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

[0019]

COMPARATIVE EXAMPLE 2 Soymilk having a solid content of 13% was prepared in the same manner as in Example 1, cooled to 10 ° C. or less, and 0.3% by weight based on the soymilk.
Of glucono delta lactone was dissolved in 4 times the weight of water and added and mixed. Thereafter, tofu was prepared in the same manner as in Example 1 to obtain freeze-dried tofu.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0025

[Correction method] Change

[Correction contents]

[0025]

[Table 3]

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4B020 LB10 LC04 LG05 LK04 LK05 LK06 LK07 LP04 LP10 LP19 LP20 LR06

Claims (4)

[Claims] 1. A mixture of starch and collagen peptide in soy milk, a coagulant for tofu added thereto, and coagulation by heating to a temperature higher than the higher of the starch gelatinization temperature and the coagulant reaction temperature. Freeze-dried tofu characterized by freezing afterwards, keeping it at a low temperature below the freezing point in a vacuum, removing water by sublimation and drying. 2. The freeze-dried tofu according to claim 1, further comprising a vegetable gum. 3. The freeze-dried tofu according to claim 1, further comprising a vegetable oil or fat. 4. A mixture of starch and collagen peptide in soy milk, a coagulant for tofu added thereto, and coagulation by heating to a temperature higher than the higher of the starch gelatinization temperature and the coagulant reaction temperature. A method for producing freeze-dried tofu, comprising freezing and maintaining the temperature in a vacuum at a temperature lower than the freezing point, and removing and drying water by sublimation.