JPS61254158A - Production of frozen bean curd (frozen tofu) - Google Patents

Abstract

PURPOSE:To obtain frozen bean curd (frozen TOFU) capable of being reconstituted into TOFU having improved quality and flavor in a large amount at a low cost, by adding soybean protein, dried soybean milk (TONYU), (modified) starch, etc., to TONYU, coagulating the TONYU, freezing the resultant TOFU directly or frying the TOFU in oil and freezing the fried TOFU, etc. CONSTITUTION:0.5-30% additive such as soybean protein, e.g. defatted soybean, dried soybean milk (dried TONYU), starch, e.g. rice starch, modified starch, e.g. alpha-starch, etc. is added to TONYU with 4-30% solid content heated at about 70 deg.C to give 8-40% solid content of the resultant bean curd (TOFU). The resultant mixture is then cooled to a temperature as low as about <=30 deg.C, and a coagulant is added thereto. The mixture is then sufficiently mixed and injected into a container, reheated to 70-95 deg.C with the container and all, kept at this temperature for 20-80min and coagulated to afford the aimed TOFU with a high solid content. The TOFU is package or without packaging is frozen at -10--40 deg.C for 30min-10hr or fried in oil and then frozen as described above. Alternatively, the frozen TOFU is treated, e.g. fried in oil and refrozen, to give the aimed frozen TOFU.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing frozen tofu that can be stored for a long period of time without any deterioration in quality. On the other hand, for producers, it is possible to produce in large quantities when raw materials are cheap, or to produce in factories when demand is low. The present invention relates to a tofu manufacturing method that is highly convenient for both consumers and producers. As described above, the present invention is an important technology for the tofu manufacturing industry, restaurants that use tofu, restaurants, households, retail stores, and the distribution industry.

[Conventional technology]

Tofu is a food that not only has a high water content but is also rich in high-quality protein and is therefore easily perishable, so at present no method of manufacturing tofu that can be stored for an extremely long period of time has been established.

Frozen tofu or Koya tofu, which is made by freezing and then drying tofu, is known as tofu that can be stored for a long period of time. It becomes a completely different food from tofu in terms of appearance and flavor.

As described above, no method has been developed for producing tofu that can be stored for a very long period of time without deteriorating its quality, and in particular, no method for producing excellent frozen tofu with these properties has been established at all. .

[Purpose of the invention]

The present invention was made to produce frozen tofu that has a texture similar to or better than that of the original tofu even after freezing and thawing the tofu.

[Structure of the invention]

When tofu is frozen, when it is thawed, the tofu has a different texture than the original tofu. This is because the moisture in the tofu crystallizes into ice, causing the protein in the tofu to deteriorate. This is because it undergoes freeze denaturation.

In this way, since tofu has a water content of around 90%, it is subject to freezing denaturation due to the moisture content, so if this moisture content is reduced, freezing denaturation can be prevented and the desired frozen tofu can be produced. I got the idea. In order to reduce the moisture content of tofu, we conducted intensive studies from physical and chemical aspects, and, quite unexpectedly, we added additives to tofu to relatively reduce the moisture content of tofu. They obtained new knowledge that it is possible to obtain a novel frozen tofu of extremely high quality, and based on this knowledge, they conducted further research and finally completed the present invention.

In the present invention, it is essential to add additives to soymilk, mix it, and coagulate it to produce tofu with a high solids content.

Additives include soy protein such as defatted soybeans and high-protein soy flour 1 isolated soy protein; dried soy milk; starches such as corn starch, sweet potato starch, potato starch, wheat starch, rice starch, tapioca starch, and potato starch; soluble starch, pregelatinized starch Modified starches such as , dextrin, pritelace gum, oxidized starch, starch ester, starch ether, crosslinked starch, and grafted starch are used alone or in combination.

As the raw soymilk to which these additives are added, any soymilk can be used. For example, raw soybeans or defatted soybeans that have not been heat-denatured are soaked in water and then processed by a conventional method. Soy milk prepared by grinding and heating water to transfer the soluble protein into hot water and separating it from okara, or Coreruga-style soy milk made by grinding soaked soybeans at high temperature and filtering them. Advantageously, soy milk produced by the University of Illinois method, which is obtained by soaking in water or dilute alkali, heating at high temperature, grinding, and forcefully dispersing the soy milk under high pressure, can be used advantageously.

Commercially available soy milk can also be used satisfactorily.

The soy milk has a solids content of 4 to 30 inches, particularly preferably 5 to 30 inches.
25 inches can be advantageously used. The solid content of tofu is adjusted by using the above-mentioned additives alone or in combination with this raw soy milk. If so, the amount added may be small; if the solid content of soymilk is low, the amount added needs to be increased.

The amount of additives such as starch added is 0.5 to 30 inches, preferably 4 to 20 inches of the product weight, and the solid content of tofu is 8 to 40 inches.
%, preferably 10 to 60%. If the amount added is less than the above range, the intended purpose of preventing freeze denaturation, imparting elasticity, and improving water retention will not be achieved, and if the amount added is too much beyond the above range, the original tofu The delicate, smooth flavor and texture will be affected, and the tofu-like quality will disappear, leading to a feeling of dissatisfaction.

Mixing of soymilk and these additives is preferably carried out at as high a temperature as possible; for example, it is preferable to add the additives to soymilk heated to 70° C., preferably 80° C. or higher.

Next, add a coagulant to the mixed soymilk and pour it into a container.
Tofu is produced by coagulating it, but in this case, if a coagulant is added when the mixed soymilk is at a high temperature as described above, the coagulation will occur too quickly and it will be difficult to pour it into a container. It is preferable to cool the mixture to a low temperature of .degree. C. or lower, preferably 25.degree. C. or lower, mix thoroughly, and pour the mixture into a container. As the coagulant, any known coagulant for tofu can be used, such as glucono delta lactone, bittern, calcium salts such as calcium sulfate, and magnesium chloride. After injecting into the container in this way,
The container is heated again to 70 to 95°C, preferably 80 to 90°C, and maintained at the above temperature for an appropriate period of time, for example, 20 to 80 minutes (preferably 50 to 60 minutes) to complete solidification.
Raw tofu with high solids content is obtained.

The raw tofu thus obtained is packaged or unwrapped and frozen in a freezer at 10 to -40°C for 30 minutes to 10 hours using a conventional method to obtain the desired frozen tofu. obtain.

In addition, according to the method of the present invention, tofu with a high solid content obtained using specific additives exhibits excellent resilience even when frozen as described above, but it is It is extremely unique in that when it is prepared into deep-fried tofu or fried tofu and then frozen, when the frozen product is thawed, it shows an extremely outstanding effect that is completely different in flavor and texture from the original fried tofu or nama-age. It is. Therefore, the present invention is particularly excellent as a method for producing frozen fried tofu and frozen raw fried food. High-quality frozen fried tofu and frozen raw fried foods with excellent restorability are novel foods that were previously unknown.

The oil treatment may be performed on fresh tofu produced by the above-described manufacturing method, or on frozen tofu.

The raw tofu or fried tofu obtained in this way is
After freezing as described above, if stored at a low temperature of about -15 to -20°C, it can be perfectly preserved for several months to several years without deteriorating quality. This can then be thawed and cooked in a conventional manner. The reconstituted tofu has excellent elasticity, texture, and flavor, and has excellent water retention properties, and is even slightly inferior to commercially available raw tofu. It's not a thing.

Therefore, according to the method of the present invention, it is possible to freely produce dried tofu that is comparable in quality to fresh tofu and has a particularly excellent flavor. However, it has now become possible to make it practically possible, and it has become possible to provide tofu, which is an excellent health food, in large quantities and at low cost. Furthermore, when this tofu is fried in oil, it is also possible to obtain frozen raw fried food or frozen tofu that has excellent quality with excellent restorability.

Example 1 10 kg of soy milk with a solid content of 14 times produced by a conventional method is cooled to 25° C. or lower, and 50 g of starch is dissolved therein. Next, add 30g of glucono delta-lactone and mix.

Pour into a container and heat at 85°C for 40 minutes. Leave to cool to obtain tofu. Freeze this in a -25°C freezer.

This frozen tofu was frozen for one month, then thawed and restored. At the same time, ordinary stuffed tofu was also frozen and stored.

The restored state is shown in the table below.

Example 2 The frozen tofu prepared in Example 1 was fried in oil at 200°C for 4 minutes to give it raw fried food, which was then frozen in a freezer at -25°C. One month later, this frozen Naimaage was taken out of the freezer along with ordinary Naimaage that had been frozen in the same way, and the taste of the ones boiled in oden was compared.The results are shown in the table below.

Example 6 Tofu is obtained in the same manner as in Example 1, except that 100 g of grafted starch is used instead of 50 g of starch.

The obtained raw tofu is fried in cooking oil at 200°C for 6 minutes, allowed to cool, and then frozen in a -60°C freezer. After 6 months, I thawed and cooked this.

There was no difference in flavor, texture, or structure from raw raw fried food.

Example 4 Frozen tofu was obtained by processing in the same manner as in Example 1 (however, 80 g of dried soy milk was used as a substitute for 50 g of starch), and this was processed in the same manner as in Example 2 to obtain high quality frozen raw fried tofu. I got it.

Example 5 The process of Example 2 was repeated using an equal mixture of dextrin and defatted soybean instead of starch to obtain frozen raw fried food.

After storing it in the freezer for a year, when it was boiled with shredded kelp, there was no difference in flavor or texture from raw namaage.

Claims (1)

[Claims] One or more of soy protein, dried soy milk, starch, and modified starch are added to soy milk, mixed, and coagulated by a conventional method to produce tofu with a high solid content, which can be frozen as it is or after being fried in oil. A method for producing frozen tofu, which comprises frying the tofu frozen in this way, or frying the tofu in oil, and then freezing the tofu.