JPH05184321A - Freeze-dried bean curd - Google Patents

Abstract

PURPOSE:To obtain the subject bean curd excellent in keeping quality, reconstituting properties, flavor, texture and springiness by keeping specific bean curd at a low temperature below the freezing point in a vacuum, removing the moisture and drying the bean curd. CONSTITUTION:The objective bean curd is obtained by mixing 100 pts.wt. soybean milk with 1.0-1.5 pts.wt. total amount of a gelling agent such as gelatin and starches such as modified starch, thermally coagulating the soybean milk with a soybean milk coagulant, preparing bean curd, keeping the resultant bean curd at a low temperature below the freezing point in a vacuum, removing the moisture and drying the bean curd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to freeze-dried tofu, which is a novel freeze-dried food which can be hydrolyzed without denaturation of components and deterioration of texture and which can reproduce particularly excellent taste and flavor like raw tofu. I will provide a.

[0002]

2. Description of the Related Art Generally, tofu has a high water content and is a raw food rich in proteins and fats, and is easily putrefaction, so that it is not easy to impart storability. Conventionally, processed tofu that has been preserved is "frozen tofu," which is raw spicy tofu that is frozen when it is extremely cold and then dried to form a spongy tissue. However, this is rehydrated because the protein freezes and denatures. However, the texture of tofu is not reproduced, and it is completely different from the original raw tofu.

On the other hand, it is known that freeze-drying, that is, freeze-drying, in which water is sublimated to remove food by keeping it at a low temperature in a vacuum, that is, freeze-drying, generally causes little change in food quality. It is considered that the production method is applied to raw tofu to avoid freezing denaturation of tissue, and the following are known examples of the freeze-dried tofu. (1) JP-A-59-28448 discloses that dextrin and / or starch is added in an amount of 2.5 to 7 per 100 parts by weight of soy milk.
There is disclosed tofu which is obtained by mixing parts by weight, coagulating it by a conventional method, and freeze-drying it in a vacuum. In this prior art 1, restoration properties such as water retention and elasticity when reconstituted with hot water are said to be improved as compared with, for example, raw tofu simply freeze-dried, but blending of a filler such as dextrin The fact is that the amount of the ingredients is too large and the Japanese who are sensitive to the flavor feel the powdery and gritty texture and flavor, and that the return time to the hot water is slow.

(2) Japanese Patent Publication No. 60-52792 discloses that
Soy milk is mixed with starch, egg white and casein, and coagulated by a conventional method, followed by freeze-drying tofu. In the prior art 2, an example in which fillers such as egg white, casein and corn starch are mixed in a total amount of approximately 12 parts by weight in terms of 100 parts by weight of soy milk liquid, and chopped into 1 cm ³ to obtain freeze-dried tofu
Regarding (see Sample 1 in Table 1 of the same publication), the tofu reconstituted with hot water had no cracks in appearance, and the texture was smooth and good (see Sample 1 in Table 2). .. However, in this example, the mixing ratio of the filler was higher than that of the prior art 1, and it was unavoidable that the taste and flavor became more powdery. In particular, the addition of egg white impairs the flavor of tofu. Further, an example in which a total of approximately 1.8 parts by weight of the above-mentioned filler is mixed in terms of 100 parts by weight of soy milk liquid to obtain freeze-dried tofu of 1 cm square (the same table-
3), the return time of the tofu reconstituted with hot water is 1
It took 20 seconds, the appearance was colored pale yellow and had cracks, and the texture was a little dull (Table 4-4).
See Sample 1). That is, in this example, although the mixing ratio of the filler was smaller than that of the conventional technique 1, it was thought that the restoration property of the tofu was deteriorated due to this, and that cracks particularly occurred in a size of about 1 cm square. Be done. Therefore, it seems that the larger tofu has a lower commercial value in terms of shape retention. An object of the present invention is to develop a freeze-dried tofu capable of extremely excellently restoring the texture and taste of raw tofu.

[0005]

[Means for Solving the Problems] The present inventor (that is, the applicant of the present invention) previously mentioned that on February 6, 1991, soybean milk was mixed with gelatin and starch and heated and coagulated by a conventional method. A tofu that can be stored at cold temperature and which can be reproduced well without causing drip even when frozen and thawed by cooling and gelling (see Japanese Patent Application No. 3-38140). The present inventor has completed the present invention based on the idea of applying freeze-drying treatment to the frozen tofu, which has a high water-retaining property at a cold temperature and a low mixing ratio of the treatment agent.

That is, in the present invention 1, tofu is prepared by mixing gelling agent and starch in a total amount of 1.0 to 1.5 parts by weight with respect to 100 parts by weight of soymilk and heat-coagulating with a soymilk coagulating agent. Then, the freeze-dried tofu is obtained by subjecting this to freeze-drying treatment in which the water is removed by sublimation and dried while being kept in a vacuum at a temperature below the freezing point. The present invention 2 is characterized in that, in the above-mentioned present invention 1, the prepared tofu is cooled to a refrigerating temperature range, the tofu component is subjected to gelation treatment with a gelling agent, and then freeze-dried. The present invention 3 is characterized in that, in the above-mentioned present invention 1 or 2, the starch is a modified starch. This invention 4 is the above invention 1
Or 2 is characterized in that the starch is a mixture of modified starch and yam flour. Invention 5
Is characterized in that the gelling agent is gelatin in any of the above-mentioned present inventions 1 to 4. Invention 6
In any one of the above-mentioned present inventions 1 to 4, the gelling agent is a mixture of gelatin and vegetable gum.

The above-mentioned soy milk includes soy milk alone, soy milk mixed with powder of yuzu, edible wild plants, green peas, spinach and the like and various flavor liquids, and the solid concentration thereof is 8 to 10.
About 13 wt% is common. Tofu is prepared by heating and coagulating soymilk liquid or soymilk powder by adding water to a liquid state and heating the mixture with a soymilk coagulant. The soymilk coagulant refers to a treating agent having a heat coagulating action on soymilk such as clarified powder containing calcium sulfate as a main component, calcium chloride, bitter juice or gluconodeltalactone.

The above-mentioned gelling agent has a gelling and solidifying property when cooled, and is capable of gelling and fixing the tofu components. Specifically, the following gelling agents may be used alone or in combination. (1) Proteins such as gelatin and casein (2) Seaweed polysaccharides such as agar, carrageenan, furcellulan, and algin (3) Xanthan gum, tamarind gum, gum arabic,
Sap polysaccharides such as guar gum and locust bean gum, seed polysaccharides and polysaccharides of microbial origin (collectively these are called plant gums), or other polysaccharides such as pectin and konjak mannan, but as a gelling agent Is JP-A-61-1
As disclosed in Japanese Patent No. 63963, it is preferable to use easily water-soluble gelatin having a high solubility in an aqueous solution, which is produced by spraying a gelatin solution on a gelatin powder held in a fluid state.

The above-mentioned starches are not limited to natural products isolated from plants such as potato, corn, sweet potato, yam and tapioca, and various treatments such as dextrin, oxidized starch and modified starch which are chemically or physically treated. It includes starch and starch derivatives such as esterified starch, etherified starch and cross-linked starch, and specifically, soluble starch and yam starch of the modified starch are preferable.

The mixing ratio of the treating agent consisting of a combination of starches and a gelling agent is 1.0 to 1.5 parts by weight, more preferably 1.2 to 1.
3 parts by weight. If the amount of the above treating agent is less than 1.0 part by weight, the water retention of the tofu component will be lowered and the restorability will be lowered.
If the amount is more than 5 parts by weight, the taste and flavor of tofu will be slightly deteriorated. In particular, when the mixing ratio of the treating agent is 1.2 to 1.3 parts by weight, when the tofu is rehydrated, it returns quickly,
The texture of tofu is smooth and elastic, and the taste and flavor are perfect compared to raw tofu. Further, even if the cut shape of the tofu is about 3 cm square, no cracks appear in the appearance and there is no problem in the shape retention. The return speed of water restoration is fast within 20 seconds.

The above-mentioned treating agent is basically a mixture of a gelling agent and starches. Specifically, it is preferable that gelatin and modified starch are mixed in equal amounts. In this case, the following effects can be obtained by making the amount of one gelatin mixed constant and replacing a part of the other modified starch with, for example, the following. Replacing the starch with yam flour smoothes the texture of the tofu and increases the fineness of the texture. Replacing with vegetable gum, which is a gelling agent, makes tofu more sticky and more elastic. Thereby, the fragility peculiar to the freeze-dried product can be improved. In this case, yam flour and vegetable gum are
Single substitution or multiple substitution may be possible.

When the soy milk is mixed with a gelling agent or a treating agent composed of starches, it is preferable to mix the soy milk in the upper and lower temperature regions around the normal temperature. For example, gelatin and modified starch are added. In the case, basically, the heat setting temperature of the soymilk coagulant is higher than the gelatinization temperature of gelatin (approximately 8
A temperature range of about 20 ° C to 40 ° C, which is 0 ° C or less, is desirable. The tofu that has been heat-solidified is left to cool, refrigerate or freeze, and then freeze-dried.However, in order to sufficiently gelate the tofu component (that is, to gelate and fix more of the water content of the food), refrigerate it once. It is preferable to freeze-dry after passing through the temperature range. Therefore, tofu is refrigerated temperature range (ie, 0 ℃ ~
It is preferable to hold the material in the refrigerating atmosphere for a predetermined time while cooling it to a chilled region of 10 ° C.), and then perform a freezing process.

The freeze-drying process is not an evaporative drying of water in an open system, but a freeze-drying process in which water is removed and dried by a sublimation method under vacuum. Prior to freeze-drying, it is general to pre-freeze in another freezing device, but it is also possible to put tofu in a refrigerated state directly into a freeze-drying device (specifically, a vacuum drying device) for self-freezing. Absent. The pre-freezing can be carried out by air freezing, air blast freezing, contact freezing, immersion freezing, liquefied gas spray freezing, or the like. To rehydrate the freeze-dried tofu, reconstitute with hot water or rehydrate.

[0014]

[Action]

(1) In the present invention, the mixing ratio of the gelling agent and both treating agents such as starches is set to a low value of 1.0 to 1.5 parts by weight per 100 parts by weight of tofu. That is, by significantly suppressing the mixing ratio of the treatment agent with respect to soybean milk as compared with the above-mentioned prior arts 1 and 2, when the freeze-dried tofu is reconstituted, the texture such as elasticity and water retention is kept high, and the original tofu is These can be reproduced well without impairing the taste and flavor of. In particular, in the prior art 2, cracking occurred when the mixing ratio of the treating agent was low even with a size of 1 cm square. However, in the present invention, even when the mixing ratio of the treating agent is low, even a cut shape of 3 cm square is rehydrated. The tofu has no cracks and the return speed is quick within 20 seconds.

(2) By adding two components, a gelling agent and starch, to soymilk, the water retention in the tofu tissue before freeze-drying treatment is improved, and the fluidity of water that is in a bound state with solutes is improved. In the freeze-drying process, the ice crystals in the tofu tissue are finely and uniformly dispersed in the freeze-drying process, and the flow of bound water that does not precipitate as ice crystals is restricted, so that the sublimation and removal of water is promoted smoothly. Can be estimated. Therefore, it is considered that the decrease in water activity and the immobilization of solutes and insoluble components proceed extremely smoothly, and the texture and taste / flavor of tofu necessary after restoration can be well secured. In this case, once the prepared tofu is frozen after passing through the refrigerating temperature range, the water content in the tofu can be gelated and fixed more efficiently.

(3) The tofu tissue was freeze-dried to have a water content of about 3
Since the water content of the tofu is extremely reduced, it is possible to reliably prevent spoilage of the tofu by microorganisms and improve the storage stability. In general, freeze-dried foods become porous and have an increased surface area, so that there are many opportunities for sorption of moisture and exposure to air, resulting in high hygroscopicity and oxidative property. It is necessary to package the material with low gas permeability such as polyethylene, nylon, or laminated film. In addition, a desiccant such as silica gel is put in the package (IPD method), antioxidants such as BHT and vitamin C and oxygen scavengers are enclosed, and the inside of the package is filled with an inert gas such as nitrogen or carbon dioxide. Gas replacement is performed. However, since the freeze-dried tofu of the present invention gels and fixes the water content in the tissue with gelatin and starch in advance, the freeze-dried tofu has resistance to moisture absorption even in an open state as compared with a normal freeze-dried product.
Preservability such as oxidation resistance function is improved. For this reason, the life cycle is significantly longer than that of conventional raw tofu, and sales, distribution, and inventory management are extremely easy.

[0017]

EXAMPLES Next, examples of producing tofu of the present invention will be described in order. << Example 1 >> An example of adding gelatin and curdlan will be described with reference to FIG. First, the air supply temperature is 70 ° C and the exhaust temperature is 35
After granulating the gelatin by spraying a 5 wt / vol% gelatin solution kept at 60 ° C. at a spraying amount of 250 ml from above 80 wt% or more of fine powdered gelatin in a fluidized state at a temperature of 70 ° C., an air feeding temperature of 70 A water-soluble gelatin was prepared by drying at a temperature of 43 ° C., an exhaust temperature of 43 ° C., a drying time of 25 minutes, and a cooling time of 15 minutes (see step 1 in FIG. 1). "Gure" that had been boiled and matured was squeezed and filtered to obtain soy milk having a solid content concentration of 12%, and the soy milk was allowed to cool to a mixing treatment temperature of about 25 to 30 ° C (procedure 2). Also, 6 g of soluble starch is added to 1 part of water.
Mix with 00cc and continue stirring for about 10 minutes
(Procedure 3) 6 g of the water-soluble gelatin was mixed and stirred to dissolve it (Procedure 4). Approximately 100 cc of a mixed solution of soluble starch and water-soluble gelatin is mixed with 900 cc of soy milk held at the above mixing temperature (procedure 5), and then a mixture of calcium salt and gluconodeltalactone is used as a main component. 3 g of soy milk coagulant was mixed (procedure 6). Pour the mixture of soy milk into a container for coagulation (step 7), 85
The soy milk was solidified by boiling at 30 ° C. for 30 minutes (procedure 8). The obtained tofu is dipped in cold water at 10 ° C. or lower in a state of being housed in the above container to gel and fix the tofu component (step 9),
It was cut into a substantially cubic shape of 3 cm square and frozen at -30 ° C or lower (procedure 10). The frozen tofu with a thickness of 3 cm is evenly placed on a tray and stored in a vacuum dryer, and 1.
The water content becomes 5.0% or less, preferably 3.0% or less under the conditions of a vacuum degree of 0 Torr or less, preferably 0.5 Torr or less, and a maximum shelf (heating plate) temperature of 80 ° C or less, preferably about 60 ° C. Until freeze-dried for about 15-25 hours (Procedure 1
1).

60 to 70 of the obtained freeze-dried tofu
The results of reconstitution with hot water at ℃ were as follows. (1) Appearance of tofu: White-like and uniform surface is maintained, and there is no cracking despite the cubic shape of 3 cm square. (2) Tofu texture: Elasticity and smoothness are comparable to those of raw tofu, and it has a soft texture and texture. (3) Tofu taste and flavor: Reproduce the taste and flavor comparable to that of raw tofu. There is no odor or powdery feeling. (4) Rehydration time: Rapid, within 20 seconds. In Example 1, even if the mixing amount of gelatin or soluble starch was increased, for example, from 6 g to 7 g, there was almost no change in the properties of the tofu rehydrated. However, the combination of 6 g of soluble starch and 7 g of gelatin made the texture of tofu smoother.

Example 2 Based on Example 1 above,
A portion of the soluble starch was replaced with yam flour while keeping the gelatin content constant. That is, by replacing approximately 17% of 6 g of soluble starch with yam flour, a mixture of 5 g of soluble starch and 1 g of yam flour was mixed and stirred in 100 cc of water, and 6 g of the gelatin was dissolved. Freeze-dried tofu was produced under the same conditions as in Example 1. When the obtained freeze-dried tofu was reconstituted with hot water, the smoothness of the tofu was increased, and the texture of the tofu became fine like a silk strainer, allowing for a milder texture.

<< Embodiment 3 >> Based on the above Embodiment 1,
A portion of the soluble starch was replaced with vegetable gum while keeping the gelatin content constant. That is, 6 g of soluble starch
By replacing about 17% of the above with tamarind gum, a mixture of 5 g of soluble starch and 1 g of tamarind gum was mixed and stirred in 100 cc of water, and 6 g of the gelatin was dissolved, and thereafter the same as in Example 1 above. Freeze-dried tofu was produced under the conditions. The freeze-dried tofu thus obtained had the fragility peculiar to the freeze-dried product described in Example 1 above.
The shape retention was further improved and the elasticity or stickiness of the tofu was improved due to the increased water retention, which was suitable for cold tofu, for example.

<Embodiment 4> Based on the above Embodiment 1,
A part of the soluble starch was replaced with a composite treatment agent of yam flour and vegetable gum while keeping the gelatin content constant. That is, by replacing 1/3 of the soluble starch 6 g with the above-mentioned two-component composite treating agent, soluble starch 4
g, 1 g of yam flour and 1 g of tamarind gum are added to 1 part of water.
The mixture was added to 00 cc and stirred, and further 6 g of the gelatin was dissolved. Thereafter, freeze-dried tofu was produced under the same conditions as in Example 1. As a result of reconstitution of the obtained freeze-dried tofu with water, smoothness and elasticity of the tofu are increased,
From Example 1, mild tofu was able to give the original natural taste and flavor of tofu. Also, the hydration restoration time could be shortened to 10 seconds or less.

[0022]

【The invention's effect】

(1) When freeze-dried tofu is rehydrated by mixing gelling agent and starch with soymilk, smoothness and elasticity similar to raw tofu can be reproduced well, and you can enjoy soft texture and texture. Moreover, by controlling the mixing ratio to a low level, the taste and flavor similar to those of raw tofu can be restored, so that a completely new and revolutionary freeze-dried tofu can be provided.

(2) Even if the cut shape of the tofu is about 3 cm square, there is no cracking in the appearance, the fragility peculiar to freeze-dried products is overcome, and the freeze-dried tofu before reconstitution with water has high shape retention. In addition to being able to give, the return speed is as fast as within 20 seconds, so that it can be widely used, for example, for large-sized sukiyaki as well as for miso soup, and the commercial value can be increased.

(3) By changing the combination components and the mixing ratio of the gelling agent and starch, the properties of the tofu rehydrated, such as smoothness and elasticity, can be improved. Further, since the treating agent added to soymilk is basically a gelling agent and starch, it can be carried out at low cost.

(4) Since the water in the tofu tissue is preliminarily gelled and fixed by the gelling agent and the starches, the storability in the open state can be improved as compared with the conventional freeze-dried food, and the stock or distribution management can be facilitated. Become. In particular, once the prepared tofu is freeze-dried after being refrigerated, it can be expected to improve the water-retaining ability by gelling and fixing, so that the above-mentioned storability is further improved. In addition, the improvement of vulnerability contributes to the reduction of transportation management labor, and the distribution management is reduced.

[Brief description of drawings]

FIG. 1 is a flowchart showing a manufacturing procedure of a first embodiment.

Claims (6)

[Claims] 1. A tofu is prepared by mixing a gelling agent and starch in a total amount of 1.0 to 1.5 parts by weight with 100 parts by weight of soymilk and heat-coagulating with a soymilk coagulant to prepare a tofu. Freeze-dried tofu characterized by being subjected to a freeze-drying process in which water is removed by sublimation and dried at a temperature below the freezing point. 2. The freeze-dried tofu according to claim 1, wherein the prepared tofu is cooled to a refrigerating temperature range, the tofu component is subjected to gelation treatment with a gelling agent, and then freeze-dried. 3. The freeze-dried tofu according to claim 1, wherein the starch is a modified starch. 4. The freeze-dried tofu according to claim 1, wherein the starch is a mixture of modified starch and yam flour. 5. The freeze-dried tofu according to any one of claims 1 to 4, wherein the gelling agent is gelatin. 6. The freeze-dried tofu according to any one of claims 1 to 4, wherein the gelling agent is a mixture of gelatin and vegetable gum.