JPS5959170A - Preparation of bean curd for preservation - Google Patents

Abstract

PURPOSE:To prepare a bean curd for preservation, preservable for a long period, giving smooth feeling to the tongue and having the excellent palatability of ordinary bean curd, in a short time in large quantities, without using troublesome procedure such as swelling. CONSTITUTION:Fresh bean curd prepared by conventional process is cooled to <=-15 deg.C as rapidly as possible to obtain a uniformly frozen bean curd. It is aged at -5-0 deg.C for 2-10 days, preferably at -3--2 deg.C for 3-5 days, and vacuum packed optionally after the addition of a seasoning. The packed bean curd is thermally sterilized at 110-140 deg.C for 20-60min, preferably at about 130 deg.C for about 50min.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing tofu that can be stored for a long period of time. More specifically, the present invention relates to a method for producing frozen tofu-like preserved tofu in large quantities in a short period of time.

Tofu is a food that has been widely used as food since ancient times, and the known methods of preserving it include vacuum-packing the manufactured tofu, or freezing, aging, and drying to make frozen tofu. It's just that. However, the former can only be stored for a few days at most and cannot be stored for long periods of time, while the latter requires many steps and time to manufacture, and must be swollen before use. Since the resulting food has a texture and taste completely different from the original tofu, neither method of preservation is necessarily satisfactory.

The inventor of the present invention has improved the drawbacks of conventional tofu for storage, and has created a tofu that can be stored in a stable state for a long period of time, and has a smooth texture without requiring any extra effort such as puffing. As a result of intensive research to develop a new type of preserved tofu, we succeeded in creating a completely new type of preserved tofu that incorporates the advantages of frozen tofu and vacuum packaging.

That is, according to the present invention, tofu produced by a conventional method is rapidly cooled and frozen, then aged at a temperature of -5°C to 0°C for 2 to 10 days, and then left as is or with the addition of seasonings. By vacuum-packing the tofu and sterilizing it at a temperature of 110 to 140° C. for 20 to 60 minutes, it is possible to obtain a new kind of tofu for preservation that has not been previously known.

Hereinafter, the present invention will be explained in more detail with reference to the accompanying drawings.

Figure 1 is a process diagram showing the manufacturing process of dough tofu used as the raw material of the present invention.As is clear from this, dough tofu, or ordinary tofu, is made by soaking soybeans in water for 10 to 12 hours at room temperature. A process of soaking the pickled beans, a grinding process of grinding the beans with a mill, a steaming process of heat-treating the ground product at 50 to 110°C for several minutes, a separation process of squeezing the processed product and separating it into soy milk and so-called okara. It is produced through a preliminary coagulation step in which separated soymilk is kept at about 80°C and an aqueous calcium chloride solution is added to coagulate the proteins, and a squeezing step in which the coagulated product is poured onto a cloth and treated under pressure.

The dough tofu produced in this way is sold as is or in vacuum packs, but since this product cannot be stored for long periods of time, it must be eaten within one or two days. The reality is that there are.

Figure 2 is a process diagram showing the manufacturing process of frozen tofu, so-called Koya tofu, which is a typical type of tofu for long-term storage.
This product is made by rapidly cooling the dough tofu produced as described above to a low temperature of about 115 parts and freezing it.
It is produced by leaving it to mature for about 20 days at a temperature of about 100°C, thawing it in a hot water bath, dehydrating it using a centrifuge, impregnating it with brine or Jiso water, dehydrating it again, and drying it with hot air. The frozen tofu obtained in this manner needs to be soaked in water to puff up and then cooked before use.

FIG. 3 is a process chart showing the process of manufacturing tofu for preservation according to the present invention.
The process consists of an aging process in which the product is stored for 2 to 10 days at a temperature of 0°C to 0°C, a vacuum packing process in which the product is packaged in plastic under vacuum, and a high temperature sterilization process in which the packaged product is heat treated at 110 to 140°C for 20 to 60 minutes. .

The freezing step in the method of the present invention is carried out by rapidly cooling the dough tofu to -15°C or lower and freezing it, as in the case of conventional frozen tofu. In this step, in order to solidify the dough tofu without damaging its taste and flavor, it is necessary to bring the tofu to a temperature of -15°C or lower as quickly as possible and freeze the whole tofu homogeneously. At this time, if the cooling rate is slow, a layered frozen layer is formed from the surface to the inside of the tofu, making it impossible to obtain a high-quality product.

Next, the aging process denatures the proteins in the frozen tofu.
It is intended to provide some degree of strength, and can be heated between -5℃ and 0℃,
Preferably at a temperature of 2 to 3°C for 2 to 10 days, preferably 3
It is carried out by holding for ~5 days.

The temperature and time of this aging are appropriately selected within the above range depending on the taste, texture, etc. required of the target product.

When producing conventional frozen tofu, the protein must be solidified to provide sufficient strength to maintain its shape after drying, which requires aging for a long period of time, but the present invention Since there is no particular need to improve the strength of protein, a short maturing time of μ to 100% is sufficient for frozen tofu.

Further, the vacuum packing step in the method of the present invention can be performed by a method commonly used for vacuum packing foods. Packaging materials in this case include plastics such as polyethylene, polypropylene, polyvinyl chloride, copolymers of ethylene and other monomers, and coated metals such as aluminum that do not have air permeability. is suitable.

When vacuum-packing, aged tofu may be packed as is, but it is convenient to add seasonings such as dashi stock to the packaging, as there is no need to prepare stock separately during cooking.

In addition, the high temperature sterilization process is performed on vacuum packed items at 110℃.
This is done by heating at a temperature of ~140°C for 20 to 60 minutes, and this treatment inactivates any bacteria that may get into the pack, and also completely solidifies the protein so that it no longer deteriorates. do. in this case,
If a relatively high temperature is used, a short treatment time is sufficient, but if a relatively low temperature is used, a long treatment time is required. Preferably, it is heated at about 130° C. for about 50 minutes.

Unlike conventional frozen tofu, the preserved tofu obtained by the method of the present invention does not need to be expanded with water during cooking, and can be used as is after tearing the package. In addition, because the protein is not completely solidified during the manufacturing process, it is a new type of food that has a unique flavor with a smooth texture.

Unlike conventional frozen tofu, which deteriorates due to oxidation and loses its commercial value in about 5 months, this tofu can be stored stably for 12 months, so it is a preserved food that is widely available in supermarkets, department stores, and stores. It is suitable as a commercial product.

The method of the present invention further has the following advantages.

(b) When a certain degree of strength is required for a dried product after hot air drying, such as frozen tofu, a long period of aging is required to solidify the protein, but in the present invention, the dried product is Therefore, the aging period can be significantly shortened.

(b) Long-term storage is possible through high-temperature sterilization, so
The thawing, dehydration and drying steps required for frozen tofu can be omitted.

(c) Since there is no need for leavening during cooking, there is no need for leavening agents such as brine, superimposed aqueous solutions, and ammonia.

B) Dry products such as frozen tofu are often damaged during packaging and transportation processes, so the yield is inevitably reduced, but the preserved tofu according to the present invention has a high yield because it is not a dried product.

Next, the present invention will be explained in more detail with reference to Examples.

Reference Example After a mixture of equal volumes of soybeans and water was allowed to stand at room temperature for 10 hours, the remaining water was removed and the soybeans were ground, and the temperature of this ground material was raised from 50°C to 110°C in a trench for 3 minutes. Steam in water. Next, this steamed product is filtered by pressing through a rice cloth to separate the soymilk having a concentration of 4 from the solid content, that is, the okara. This soymilk was cooled to 80℃ in a trench, 2t of Baume 20℃ calcium chloride aqueous solution was added to 350t, and the proteins in the soymilk were coagulated by mixing well. and leave it for 5 hours.

In this way, a dough σ-rot with considerable hardness was obtained.

Example 1 The dough tofu obtained in Reference Example was rapidly cooled to -15°C and completely frozen, and then placed in a refrigerator maintained at -3°C for 5 days. Next, this is vacuum-packed into a non-porous polyethylene container using a commonly used vacuum-packing device, and this is sterilized at high temperature at 130° C. for 50 minutes in a hot-air heating device.

When the preserved tofu thus obtained was opened after one month and used for cooking as miso soup, the resulting food had the flavor of doughy tofu and was soft to the touch.

Also, this product was used for cooking after being stored for 12 months.
No change in texture was observed.

Example 2 Preservative curd with seasoning diagonally added was produced in the same manner as in Example 1, except that approximately the same amount of bonito stock as tofu was added during vacuum packing.

This product could be made edible by simply seasoning it with soybean oil during cooking.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing a method for manufacturing dough tofu, FIG. 2 is a process diagram showing a conventional method for manufacturing frozen tofu, and FIG. 3 is a process diagram showing a method of the present invention. Patent Applicant Hara Minor Agent Isomorphic Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 After rapidly cooling and freezing the dough tofu, the temperature is -5°C to θ°C.
A method for producing tofu for storage, which comprises aging the tofu for 2 to 10 days at a temperature of 110 to 140 °C for 2 to 10 days, then vacuum-packing it, and sterilizing it at high temperatures for 20 to 60 minutes at a temperature of 110 to 140 °C. 2 After rapidly cooling and freezing the dough tofu, -5℃ to 0℃
It is aged for 2 to 10 days at a temperature of
A method for producing tofu for preservation, characterized by high temperature sterilization for 0 to 60 minutes.