JPH11169128A - Bean curd having freeze resistance and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the freeze denaturation of bean curd without influencing on the quality of the bean curd before freezing by adding a starch having a specific particle diameter to soya milk. SOLUTION: Bean curd capable of keeping the taste, the feeling to the tongue and the palatability even by thawing after storage in frozen state can be produced by incorporating soya milk with a starch having an average particle diameter of <=10 μm, preferably a particle diameter range of <=10 μm. Preferably, the soya milk is incorporated with the starch at 50-75 deg.C and heat-treated. The starch is preferably taro starch and/or rice starch because these starches are composed of uniform small particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to tofu having freeze resistance, and more particularly to tofu having a quality comparable to that of conventional products before and after freezing.

[0002]

2. Description of the Related Art It is well known that when tofu is frozen, it cannot be restored to its original state even after thawing, resulting in a completely different tissue. Being manufactured.

[0003] By storing frozen tofu and thawing,
If you can get something that is comparable to normal tofu, cut it appropriately and store it in a frozen state.You can use the necessary amount for pots and miso soup when needed. Frozen marbo tofu that can be eaten is possible.

[0004] From such a viewpoint, attempts have been made to improve the freezing denaturation of tofu. Means for producing freeze-dried tofu by adding natural gums or natural gums and a wetting agent to soy milk (Japanese Patent Application Laid-Open No. 52-90650), means for adding an emulsifier to soy milk (Japanese Patent Application Laid-Open No. 54-154247), Means for producing freeze-dried tofu by adding sugars to soy milk
No. 5,153,574) have been proposed, but all of them have not only escaped the tofu-like region, but also have a problem that the use of an emulsifier or the like leads to a decrease in flavor and taste.

[0005] There is also an attempt to improve the freeze denaturation of tofu using starch. For example, means for adding a processed starch having a freeze-tolerance and a saccharide having a low sweetness, preferably a protein and transglutaminase to soymilk (JP-A-6-21)
No. 7729), means for adding gelatin and starch to soymilk (Japanese Patent Application Laid-Open No. 6-217730), means for adding dextrin and / or starch to soymilk and performing degassing treatment (Japanese Patent Application Laid-Open No. 6-1).
No. 13777), means for adding fats and oils, starch, a thickener and the like to soymilk (Japanese Patent Application Laid-Open No. 5-336916) and the like have been proposed. Japanese Patent Application Laid-Open No. 9-215479 discloses a method of adding etherified starch having a substitution degree of 0.04 to 0.2 from tapioca starch, potato starch, and waxy corn starch to soymilk.

However, in these methods, the case of eating without freezing is not considered in any case, and it is examined from the viewpoint of whether or not it has the property of tofu when thawed after frozen storage. In addition, the tofu obtained is not so crisp and textured that it can be eaten cold. In these proposals, the use of starches is disclosed, but no consideration is given to the effect of starch particle size on the improvement of freeze denaturation of tofu, There is no suggestion in this regard. Japanese Patent Application Laid-Open No. 9-215479
The average particle size of tapioca starch described in
m, potato starch 40 μm, corn starch 15 μm
(Cooking Science, Vol.6 No.2, P78, 1973).

[0007] In recent years, the number of people living alone, including those who have been relocated alone, has increased, and there is too much tofu for one person, and there is a situation in which it is difficult to preserve the remaining tofu. Therefore, if there is tofu that is not only cryopreserved but also has a quality comparable to that of the conventional product in a normal sales form, it will be a very gospel for a person living alone.

As described above, various attempts to improve the freezing and denaturation of tofu have been proposed, and each of them is somewhat effective for the purpose of improving the freezing and denaturation.
Those that could be eaten equally without being frozen and the rest were stored frozen and thawed were not inferior to those of commercially available products, and all were still unsatisfactory in terms of tofu that could be eaten as a cold roll.

[0009]

The problem to be solved by the present invention is that when not frozen, it has a quality that can be used as a normal product, and the flavor that has been thawed after freezing and storage is comparable to that of a normal product. Another object of the present invention is to provide a tofu having a freezing resistance that can provide a texture, texture and texture.

[0010]

In view of the above situation, as a result of intensive studies to solve the above-mentioned problems, surprisingly, the use of starch having a particle smaller than a specific limit among starches has led to The present inventors have further found that freezing denaturation can be prevented without affecting the quality before freezing.

That is, the present invention relates to a tofu having a freezing resistance obtained by adding a starch having an average particle size of 10 μm or less to soy milk in the production of the tofu.
At a certain temperature, the starch is added and heat-treated, and more preferably the starch having an average particle size of 10 μm or less relates to a freeze-resistant tofu using taro starch and / or rice starch.

[0012]

In the present invention, tofu means a soy milk having a predetermined shape without coagulation by adding a coagulant such as natural bittern, calcium sulfate, calcium chloride, glucono delta lactone to the soy milk and filtering and dehydrating the soy milk. It refers to ordinary tofu that has been hardened in a tofu and fried tofu. In addition, soy milk is obtained by immersing whole soybeans in water, grinding, adding water, heating and then squeezing to separate okara, which is generally used for the production of tofu, and also obtained from full fat soy milk powder. Soy milk and soy milk obtained by adding water and vegetable oil to isolated soy protein and emulsifying it.

The starch used in the present invention has an average particle size of 1
A starch having a particle size of 0 μm or less. Such starch can be obtained by classifying wheat starch containing large particles and small particles, potato starch, etc., and extracting only small particles, and the size of the starch granules contained varies depending on the type of plant, It can also be obtained by selecting a starch obtained from a plant that originally contains only small starch particles. The former is difficult to completely classify commercially, and it is inevitable that large and small particles are mixed. In contrast, the latter is more effective and preferable because the particles are uniform in size.

Examples of the latter include taro starch having an average particle size of about 1 μm and rice starch having an average particle size of about 5 μm. In these, small particles are arranged so that there are no large particles exceeding 10 μm. Preferred. Taro starch is a starch separated and collected from taro, and rice starch is a starch separated from non-glutinous rice and glutinous rice, regardless of the type of rice, for example, single grain rice or long grain rice. Among these, in terms of long-term freezing storage resistance, glutinous rice starch is the most excellent and preferable.

In the case of starch having an average particle size exceeding 10 μm, the texture after freezing,
Not only does the tongue not be of a quality that can be eaten as a cold guy,
In particular, the texture and texture before freezing are inferior. Even if the average particle diameter is 10 μm or less, if the particle diameter exceeds 10 μm, the effect is inferior to that part. Therefore, it is desirable to select starch having a particle diameter of 10 μm or less as a whole. Taro starch (particle size about 0.2 ~
3 μm), glutinous rice starch and non-glutinous rice starch (particle size: about 2 to 8 μm).

As described above, in the present invention, the average particle size is 1
A starch having a particle size of 0 μm or less, preferably 10 μm or less is used, but the lower limit of the particle size is not particularly limited. However, the available starch of small particles is taro starch, and in this sense, the preferred starch particle size can be said to be 0.2 to 10 μm.

The starch used in the present invention may be unprocessed starch or a means generally used in starch processing such as esterification, etherification, cross-linking, sodium hypochlorite treatment, and moist heat treatment. May also be processed.

The details of these modified starches are as follows. That is, the esterified and etherified starch is obtained by reacting a commonly used esterifying agent or etherifying agent such as acetic anhydride, vinyl acetate monomer, octenylsuccinic anhydride, succinic anhydride or propylene oxide on the above-mentioned starch in a conventional manner. The degree of substitution (expressed in the number of substituents per glucose of starch) from 0.01 to
Esterified starch or etherified starch treated to 0.2.

The cross-linking treatment refers to cross-linked starch obtained by allowing a commonly used cross-linking agent such as phosphorus oxychloride, metaphosphate, adipic acid to act on starch in a conventional manner. In this case, if the crosslinking is too strong, the swelling of the starch tends to be suppressed and the effect tends to be weakened. Therefore, when the viscosity is measured at a concentration at which the peak viscosity becomes 800 to 1000 BU on a pravender amyrograph, the peak viscosity of the crosslinked starch becomes lower. 6 of peak viscosity of original starch
It is preferred to keep it to a level of at least 0%.

The hypochlorous acid treatment refers to a product obtained by treating starch with sodium hypochlorite, and generally includes a method in which starch molecules are partially cut to reduce viscosity due to bleaching degree. It refers to what is called soluble starch. The wet heat treatment adjusts the moisture of the starch to around 20% by weight,
This refers to starch that has been heat-treated to about 130 ° C. Since the heat-moisture treated starch has the same properties as the crosslinked starch, it is preferable to keep the same degree as in the case of the crosslinked starch. Further, a combination of the above-described processings is also included.

The freeze-resistant tofu of the present invention can be obtained by adding a starch having an average particle size of 10 μm or less to soy milk during the production of tofu. The amount of starch added is adjusted depending on the desired degree of freezing tolerance (freezing period) and the like, but is generally 1 to 7% by weight based on the soymilk. If the amount of starch added to soymilk is less than 1% by weight, the freezing resistance becomes insufficient, and if it exceeds 7% by weight, the paste becomes textured before freezing and becomes hard after freezing. It is not preferable because it tends to be too much.

The starch can be added to the soymilk directly in powder form while stirring the soymilk.
It is preferable that the starch is dispersed in about twice the amount of water and starch is easily dispersed uniformly in soymilk.

Tofu is produced by adding a coagulant to soy milk and coagulating the soy milk liquid. The starch may be added to the soymilk before or after the addition of the coagulant or simultaneously with the coagulant, as long as the coagulation of the soymilk does not occur. The point is that the starch is added to the soymilk so that the soymilk liquid solidifies after the soymilk is added. From this point of view, it is preferable to add starch before adding the coagulant because there is no operation error. Furthermore, before the soy milk solidifies,
When the starch is added to soymilk at a temperature at which a part of the starch swells when added to the soymilk, the starch is easily dispersed uniformly in the soymilk, and tofu of constant quality is obtained, which is preferable.

The soymilk temperature at which a part of the starch swells means the temperature at which the starch starts to gelatinize or slightly higher. The gelatinization start temperature of starch differs depending on the type of starch, the presence or absence of processing, and the degree of processing, and the gelatinization start temperature is measured at a concentration at which the maximum viscosity becomes about 700-1000 BU using a Brabender amyrograph. It is practical to use the temperature at which the viscosity starts to appear as the standard gelatinization start temperature. The preferred soymilk temperature for adding starch, taking into account the gelatinization initiation temperature depending on the type of starch, is generally in the range of 50 to 75 ° C. When starch is added at a temperature at which the added starch does not swell, for example, at room temperature, a portion of the starch tends to settle and become uneven, and the added starch gelatinizes,
When added at such a high temperature that the starch particles are disintegrated, the resulting tofu gel tends to be weak.

In the production of the tofu of the present invention, the starch and the coagulant are added, and the mixture is heated to sufficiently swell the starch and completely coagulate the soymilk liquid. At that time, the tofu may be filled in a molding container and subjected to heat treatment, or after the whole is subjected to heat treatment, appropriately dehydrated to produce a tofu having a desired hardness, and may be cut into a desired shape and molded. . Depending on the coagulant to be used, the soymilk liquid may be coagulated, dehydrated, molded, and then heat-treated. Heat treatment is about 85-95 ° C
For 2 to 60 minutes.

As the coagulant used in the present invention, a coagulant generally used in the production of tofu can be used, and specific examples thereof include calcium sulfate, magnesium chloride, calcium chloride, natural bittern, glucono delta lactone and the like. No. It is preferable to add about 0.2 to 1 part of these to powdery or lukewarm water by dissolving or dispersing them in 100 parts of soy milk and then adding the starch as described above.

The tofu of the present invention thus obtained has a texture,
The tongue texture and taste are the same as those of the conventional product, and even after being frozen and thawed, the tofu has the same texture, tongue and taste, and has a quality that can be eaten as a cold roll.

Hereinafter, the present invention will be described in more detail with reference to Reference Examples and Examples. In the reference examples and examples, “parts” means “parts by weight” and “%” means “% by weight”.

[0029]

REFERENCE EXAMPLE 1 100 parts of potato starch was dispersed in a solution obtained by dissolving 20 parts of sodium sulfate in 120 parts of water, and 30 parts of a 3% aqueous sodium hydroxide solution and 6 parts of propylene oxide were added thereto and reacted at 42 ° C. for 21 hours. Later, neutralize with hydrochloric acid,
Washing with water, dehydration and drying gave hydroxypropyl potato starch. The substitution degree was 0.103.

[0030]

REFERENCE EXAMPLE 2 The same procedure as in Reference Example 1 was repeated except that the potato starch was changed to waxy rice starch and the amount of propylene oxide was changed to 10 parts. I got

[0031]

Example 1 Whole soybeans immersed in water were ground in accordance with a conventional method, heated, and filtered. 100 parts of soymilk obtained were each brought to the temperature shown in Table 1, and various starches shown in Table 1 were mixed with 3 parts of starch.
After cooling to 40 ° C., 0.28 parts of glucono delta lactone was added, and the soymilk was then molded (8 cm ×
(8 cm × 5 cm) and heated at 90 ° C. for 30 minutes.
Then, it was put in water, cooled, taken out of the container and exposed to running water, and evaluated according to the following criteria. Table 1 shows the results. In addition, what was manufactured similarly without adding starch was made into the control example. As evaluation criteria, those that are evaluated to be comparable to commercially available tofu with respect to flavor, texture, and texture are good (◎), and slightly inferior to commercially available products, but generally good to eat as tofu (○), Those which were inferior to commercial products and hard to produce tofu were evaluated as slightly poor (△) and poor (×) depending on the degree.

[0032]

[Table 1]

In Table 1, the average particle size of starch is a value measured by a laser diffraction particle size analyzer SALD-1000 (manufactured by Shimadzu Corporation). Also, among the types of starch,
Wheat starch having an average particle size of 17.6 μm (containing about 76% of large particles exceeding 10 μm) is a commercially available ordinary wheat starch, and 7.5 μm wheat starch (containing about 31% of large particles exceeding 10 μm). (Including about 54% of large particles exceeding 10 μm) are commercially available wheat starch (Comparative Example 1) and classified wheat starch (Example 1). )), The gelatinization start temperature is 53
The waxy rice starch at ° C. is the etherified waxy rice starch obtained in Reference Example 2, the HPS is the hydroxypropyl potato starch prepared in Reference Example 1, and the others are untreated taro starch, non-glutinous rice starch, and glutinous rice starch.

[0034]

Example 2 Of the seven types of tofu evaluated in Example 1, Comparative Examples 1 and 3, and Examples 1 to 5,
Table 2 shows the results of freezing in a freezer at −40 ° C., storage at −20 ° C. for 1 week, thawing at room temperature, and similarly evaluating. The glutinous rice starch used was tofu obtained in Example 1 by adding to soy milk at 65 ° C.

[0035]

[Table 2]

[0036]

EXAMPLE 3 To 100 parts of soy milk at 69 ° C., the non-glutinous rice starch and the glutinous rice starch (unprocessed product) used in Table 2 were added in the amounts shown in Table 3, and 0.25 part of calcium sulfate was dispersed in lukewarm water. After adding and mixing, the mixture was left for 10 minutes to solidify. This was taken in a mold box, put on a weight and pressed to produce noodle tofu. Cut and pack the obtained tofu,
After heating at 90 ° C. for 10 minutes, the mixture was cooled in running water. Then, it frozen at -40 degreeC, and stored at -20 degreeC. After one month of frozen storage, the samples were thawed at room temperature and evaluated.

[0037]

[Table 3]

[0038]

Example 4 10 parts of dried soymilk powder was dissolved in 90 parts of water, an antifoaming agent was added, and the soymilk obtained by boiling under heating was cooled to 67 ° C. to give a glutinous rice starch (average particle size of 5.4 μm). Five parts were added, mixed, and allowed to cool to 45 ° C. To this was added 0.3 parts of glucono delta lactone, and a filled tofu was produced according to Example 1 below. After tasting half of the tofu that has been exposed to the cold as a cold, and storing the other half in a home freezer for two weeks,
Thawed at room temperature and tasted as cold. Both had flavors, textures, and textures comparable to those of commercial products.

Claims (5)

[Claims] 1. A freeze-tolerant tofu characterized in that a starch having an average particle size of 10 μm or less is added to soy milk in the production of tofu. 2. A method for producing freezing-resistant tofu, comprising adding a starch having an average particle size of 10 μm or less to soy milk during the production of tofu. 3. The method according to claim 2, wherein the starch is added at a time when the temperature of the soymilk is in the range of 50 to 75.degree.
3. The method for producing tofu having freeze resistance according to item 1. 4. The freeze-resistant tofu according to claim 1, wherein the starch having an average particle size of 10 μm or less is taro starch and / or rice starch. 5. The method for producing freezing-resistant tofu according to claim 2, wherein the starch having an average particle size of 10 μm or less is taro starch and / or rice starch.