JPH09215479A - Bean curd having freezing resistance and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain smooth bean curd having freezing resistance, little in the separation of water, and excellent in gel strength, water holdability, elasticity and texture by adding an etherified starch and a coagulating agent in specific amounts, respectively, to a bean milk. SOLUTION: This bean curd is obtained by adding 5-40 pts.wt. of an etherified starch produced from tapioca starch, potato starch or waxy starch as a raw material and having a substitution degree of 0.04-0.2, and 3-4 pts.wt. of a coagulating agent such as bittern, calcium sulfate or glucono-δ-lactone to 1000 pts.wt. of a bean milk.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing tofu characterized by freezing resistance, which is capable of favorably retaining the characteristics peculiar to tofu even when it is stored frozen. That is, the present invention relates to a method for producing tofu having suitable texture and freezing resistance as ingredients for various foods (for example, frozen foods such as miso soup, sukiyaki and marbo tofu).

[0002]

2. Description of the Related Art When tofu is frozen, it is difficult to retain the original texture of tofu because the water is severely separated during thawing and the tissue is destroyed. Therefore, conventionally, raw tofu has been treated as a completely different food called "frozen tofu" by freeze-drying.

As a method for improving this, a method of adding a gelling agent and a saccharide-based treating agent (JP-A-5-316984)
Have been proposed, and soluble starch and cyclodextrin are preferred as the sugar-based treating agent. With this method, the water separation after freezing and thawing is slightly improved, but it is harder than before freezing and is not preferable in terms of elasticity and the like.

Further, addition of oils and fats, starch, thickeners and the like has been proposed (Japanese Patent Laid-Open No. 5-336916), and any starch can be used so long as it can be used in foods. With this method, the tissue destruction of tofu is slightly improved, but the water separation after freeze-thawing is severe, and it is harder than before freezing, making it feel dry.

[0005]

[Problems to be Solved by the Invention] These problems, namely,
It gives freezing resistance to tofu, and overcomes the problem of maintaining a suitable gel strength, and even after thawing, it has excellent water retention,
It is to provide tofu that has a smooth texture and elasticity and a good texture.

[0006]

Means for Solving the Problems As a result of repeated studies by the present inventors, the problems remaining in the above proposal, namely, giving freezing resistance to tofu and maintaining a suitable gel strength,
The present invention has been completed by finding that it can be remarkably improved by using tapioca starch, potato starch or waxy corn starch and using etherified starch having a substitution degree in the range of 0.04 to 0.2, and completed the present invention.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As the etherification applied to the modified starch in the present invention, etherification such as hydroxypropylation, hydroxylethylation, carboxylmethylation and the like can be shown. It can be easily achieved by reacting the obtained drug according to a conventional method. For example, as the reaction agent, propylene oxide can be exemplified in the case of hydroxypropylation. In addition, mild oxidation to the extent that the physical properties of the etherification of the present invention are not impaired,
Acid treatment, bleaching treatment, or crosslinking treatment may be performed.

The degree of substitution of etherification (D.
S. ) Means the average value of the substituted hydroxyl groups per anhydroglucose residue, and D. S. It is preferable to use tapioca starch, potato starch or waxy corn starch in the range of 0.04 to 0.2, and if the substitution degree is 0.04 or less, the freezing resistance is insufficient and the amount of water separation slightly increases, which is not good. Also 0.
When the degree of substitution is 2 or more, the tofu becomes viscous and loses its original texture.

The water separation rate used in the examples of the present invention is a value obtained by dividing the difference between the weight of tofu after production and the weight of tofu after freeze-thawing by the weight of tofu after production.

The breaking strength used in the examples of the present invention means the breaking of a measuring tofu sample piece having a thickness of 3 cm using a rheometer (made by Fudo Kogyo Co., Ltd.) with a spherical plunger having a diameter of 10 mm. The strength was measured as an average of three measurements.
The table rising speed was 6 cm / min.

The amount of the modified starch used in the present invention is slightly different depending on the kind of substitution degree and the substitution degree.
It is 5 to 40 parts by weight with respect to 00 parts by weight. If it is 5 parts by weight or less, the freezing resistance is insufficient and the effect is small. If the amount is 40 parts by weight or more, the texture of tofu is lost, which is not preferable.

As the coagulant used in the present invention, bittern, calcium sulfate, glucono delta lactone and the like are used, and 3 to 4 parts by weight is used per 1000 parts by weight of soymilk.

With respect to the method of using the starch of the present invention, the effect can be obtained by a commonly known method of adding starch. As an example, there may be mentioned a method in which the starch of the present invention is stirred and dispersed in a coagulant previously dissolved in water, and the starch is added to soy milk and stirred and dispersed, and then the tofu is solidified by heating.

As described above, the produced tofu does not release water even after being frozen and thawed, and it is possible to provide a tofu having smoothness and elasticity and a good texture.

Hereinafter, the present invention will be described specifically with reference to Examples, in which all parts are expressed as parts by weight.

[0016]

【Example】

Example 1 A solution prepared by dissolving 300 parts of sodium sulfate and 10 parts of sodium hydroxide in 1200 parts of water was prepared for each sample number shown in Table 1, and 1000 parts of raw material starch and propylene oxide as an etherifying agent were added as shown in Table 1. After reacting at 40 ° C. for 20 hours, it was neutralized with hydrochloric acid, washed with water, dehydrated and dried to obtain hydroxypropyl starch. Table 1 shows the substitution degree.

[Table 1] In the table, T starch is tapioca starch, P starch is potato starch, W
Starch indicates waxy corn starch, C starch indicates corn starch, and H starch indicates high amylose corn starch.

Example 2 As a control example, 8 parts of starch without addition of starch and 8 parts of unmodified raw starch and all of the modified starches of all sample numbers prepared in Example 1 were added, Was prepared as shown in to produce tofu. Water 2
After stirring and dispersing 8 parts of starch in 1.4 parts of magnesium chloride dissolved in 0 part of the mixture, 400 parts of soybean milk was added thereto, and the mixture was stirred and dispersed, and heated to 85 ° C. to coagulate. The obtained tofu was immersed in cold water to gel and fix the tofu component. This was cut into test tofu pieces, frozen in a freezer for 1 week and then thawed, the water separation rate and breaking strength were measured, and the gel state was examined by comparing with the state before treatment. The results are shown in Tables 2 and 3.

[Table 2]

[Table 3] In the table, T starch is tapioca starch, P starch is potato starch, W
Starch indicates waxy corn starch, C starch indicates corn starch, and H starch indicates high amylose corn starch.
The evaluations in Tables 2 and 3 were evaluated according to the following criteria. ⊚: No water separation, moderate gel strength, good texture, and texture of tofu. ◯: The texture is good and the texture of tofu is present, but there is some water separation. X: A large amount of water was released, the structure was destroyed, and a large change was observed in the physical properties after treatment. Alternatively, there is little water separation and no tissue destruction, but it is sticky, sticky, and the texture of tofu disappears.

Example 3 The modified starches of Sample Nos. 2, 3 and 4 prepared in Example 1 were respectively 1, 2, 4, 8, 1 respectively.
Tofu was prepared by adding 6 and 24 parts as described below. Starch was stirred and dispersed in 1.4 parts of magnesium chloride dissolved in 20 parts of water, and then the soymilk 400 was added.
In addition to the parts, the mixture was stirred and dispersed, heated to 85 ° C., and solidified. The obtained tofu was immersed in cold water to gel and fix the tofu component. This was cut into test tofu pieces, frozen in a freezer for 1 week and then thawed, and the water separation rate and breaking strength were measured, and the gel state was examined by comparing with the state before treatment. The results are shown in Table 4.

[Table 4] The evaluations in Table 4 were evaluated according to the following criteria. ⊚: No water separation, moderate gel strength, good texture, and texture of tofu. ◯: The texture is good and the texture of tofu is present, but there is some water separation. X: A large amount of syneresis and destruction of tissue. Alternatively, there is little water separation and no tissue destruction, but it is sticky, sticky, and the texture of tofu disappears.

Example 4 Sample No. 4 prepared in Example 1
Tofu was prepared by adding 8 parts of the modified starch of Example 1 and adjusting as follows. Starch was stirred and dispersed in 1.4 parts of magnesium chloride dissolved in 20 parts of water.
In addition to 00 parts, the mixture was stirred and dispersed, heated to 85 ° C., and solidified. The obtained tofu was immersed in cold water to gel and fix the tofu component. This is cut into a suitable size, and after freezing,
Vacuum drying was performed to produce freeze-dried tofu. As a result of reconstitution of the obtained freeze-dried tofu with water, it was a good tofu with a smooth texture.

As can be seen from the above examples, the modified tapioca starch, the modified potato starch or the modified waxy corn starch which has been etherified to a degree of substitution of 0.04 to 0.2 is another raw material starch. From the modified starch from
It is clear that it is excellent in terms of water separation and changes in physical properties.
Therefore, the frozen tofu using this is useful and excellent as a frozen food or an ingredient thereof.

[0021]

EFFECTS OF THE INVENTION Frozen tofu produced using the starch of the present invention is a preferable product having no tissue destruction due to freezing, almost no change in physical properties, suitable gel strength, and almost no water separation.

Claims (3)

[Claims] 1. The degree of substitution using tapioca starch, potato starch or waxy corn starch as a raw material is 0.04 to 0.2.
Tofu characterized by freezing resistance, which is produced by adding etherified starch in the range of 1. to soymilk. 2. Tofu characterized by freezing resistance, wherein 5 to 40 parts by weight of the etherified starch according to claim 1 and 3 to 4 parts by weight of a coagulant are added to 1000 parts by weight of soy milk. 3. A method for producing tofu characterized by freezing resistance, which comprises adding 5 to 40 parts by weight of the etherified starch according to claim 1 and 3 to 4 parts by weight of a coagulant to 1000 parts by weight of soy milk.