JPH08131111A - Production of bean curd capable of being stored for long period - Google Patents

Abstract

PURPOSE: To obtain a bean curd excellent in taste, flavor and long period storage stability without deteriorating the quality by packing the bean curd, subjecting the packed bean curd to sterilization treatments such as a heat- resistant spore germination-stimulating treatment, and subsequently cooling the treated bean curd. CONSTITUTION: This method for producing a bean curd capable of being stored for a long period comprises packing the bean curd produced by a conventional method, subjecting the packed bean curd to a heat-resistant spore germination- stimulating treatment in a temperature zone of 60-100 deg.C for 1-60min to a heat- resistant spore germination treatment in a temperature zone of 10-60 deg.C for 1-180min, and subsequently to a sterilization treatment in a temperature zone of 60-100 deg.C for 1-40min, and finally cooling the treated bean curd. After the sterilization treatment, the bean curd is preferably stored at <= a room temperature.

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 long-term storable tofu, which is intended to retain a good taste and flavor without deterioration in quality even after being stored for a long period of time.

[0002]

2. Description of the Related Art Tofu is a traditional food containing high quality vegetable protein and fatty acids, but it contains a lot of water (about 90%) and contains a nutritional source (protein).
It is difficult to maintain a good taste and flavor even when stored in a refrigerator, and it is a food with low shelf life.

[0003] So far, attempts have been made to develop techniques for improving the preservability of tofu, but most of them have been tofu or microbial sterilization in tofu by a heating operation in the process of producing tofu. Heat sterilization has the advantage of being easy to incorporate into the heating step of soy milk or tofu, but for stable room temperature storage, ultra-high temperature sterilization is required to sterilize heat-resistant spores of bacteria,
A method (1) for producing aseptic tofu from aseptic soymilk by ultrahigh temperature treatment has been proposed (1).

Further, a method of mixing a tofu obtained by a conventional method with a coagulant, filling the container, and heating under pressure (JP-A-60-
149354) has also been proposed (2).

Next, as a heat sterilization technique for the purpose of extending the storage period under refrigerated conditions (10 ° C. or less), a method of sterilizing the packaged tofu produced by a conventional method as it is at 100 ° C. or less (special Kosho 62-15183) is also proposed (3).

Further, a method of converting heat-resistant spores into a heat-labile vegetative cell type and sterilizing by heating (Japanese Patent Publication No. 53-8780).
Japanese Patent Publication No. 55-39303) (4) and a method for preserving soymilk (Japanese Patent Laid-Open No. 52-148647).
No.) proposed (5).

[0007]

Problems to be Solved by the Invention In the case of the above-mentioned proposal (1), there is a problem that the soymilk component is browned by heating at an extremely high temperature, a heating odor is generated, and the soymilk coagulating power is lowered due to excessive heat denaturation of the soymilk protein. While it is always difficult to strike a balance between ensuring the effect and preventing the deterioration of the quality of soymilk, even if aseptic soymilk is obtained by heating at an ultrahigh temperature, subsequent packaging and coagulation steps also need to be performed aseptically, There were various problems, such as the requirement for a higher degree of microbial control than the tofu manufacturing equipment used.

Further, according to the proposal (2), the protein in the coagulation is excessively denatured during heating, browning and heating odor are generated as in the case of ultra-high temperature sterilization, and the tofu after coagulation is hardened. There was a problem that the texture was far from that of tofu.

According to the proposal (3), in order to obtain a stable bactericidal effect by heating at 100 ° C. or lower, it depends on the weight of tofu and the difference in microbial control during the production process, but at least several tens of minutes are required. As a result of the need for heating, hardening of tofu occurs due to heating, and there is a problem in texture that is different from untreated tofu.
If heat treatment at a temperature below ℃ for a short time causes less hardening of tofu and less quality change, it is not effective in sterilizing heat-resistant spores of bacteria. There was a problem that the residual bacteria varied and the increase in the number of bacteria varied even when stored under refrigeration, making it impossible to ensure stable storage.

Further, according to the proposal (4), there is a problem of ultra-high temperature sterilization such as browning of tofu, generation of heating odor, and reduction of coagulation power for ultra-high temperature sterilization, and only production of filled tofu. Limited to

According to the proposal (5), there is a problem that it is not limited to the filling tofu, but it cannot be used for the production of silken tofu or cotton tofu in which secondary contamination in the next step is inevitable.

[0012]

SUMMARY OF THE INVENTION Therefore, according to the present invention, a packaged tofu is subjected to a germination stimulation treatment step of heat-resistant spores at a relatively low temperature,
By passing through the germination step of heat-resistant spores and the heating bacterium treatment step, we succeeded in producing tofu that can be sterilized reliably and stably by heating at a relatively low temperature, and does not suffer heat denaturation, etc. is there.

That is, according to the present invention, after tofu produced by a conventional method is packaged, a heat-resistant spore germination stimulation step, a heat-resistant spore germination step, and a heat sterilization step are successively performed to sterilize and then cool. This is a method for producing long-term storable tofu.

According to another invention, in the germination stimulating treatment step of heat-resistant spores, the temperature is higher than 60 ° C. and lower than 100 ° C.
In the germination step of heat-resistant spores, the treatment time is from 1 minute to 180 minutes in the temperature range of more than 10 ° C and less than 60 ° C, and in the heat sterilization treatment step,
It is characterized in that it is treated in a temperature range of over 100 ° C and under 100 ° C for 1 minute or more and 40 minutes or less, and after sterilization, it is cooled to room temperature or below and refrigerated.

In the above, the temperature of the germination stimulation treatment step of the heat-resistant spores is preferably 70 ° C. to 85 ° C., and the time is preferably 20 minutes or more and 40 minutes or less. In the above, if the heating temperature is 60 ° C or lower, the germination stimulating effect is drastically reduced, and
If the temperature is 00 ° C or higher, heat denaturation may occur. Therefore, the temperature is set higher than 60 ° C and lower than 100 ° C.

Since the temperature and time for germination of the fungus are appropriately selected depending on the flora of the heat-resistant spores, the effective germination condition is 1
It is set in multiple stages of more than 0 ° C. and less than 60 ° C. for 1 minute or more and less than 180 minutes.

Next, the heat sterilization is preferably maintained at a temperature range of 80 ° C. to 90 ° C. for 5 minutes to 30 minutes. When the heat sterilization temperature is 60 ° C. or lower, the sterilizing power is remarkably reduced, and when it is 100 ° C. or higher, various problems due to protein heating occur. Therefore, the temperature is set higher than 60 ° C. and lower than 100 ° C. It is common and effective to carry out the temperature control in water. The quality of the treated tofu after heat sterilization can be maintained by quickly cooling with cold water and refrigerating.

[0018]

The present invention effectively sterilizes heat-resistant spores, which is a factor that limits the shelf life of tofu products, so that the heat-resistant spores in tofu are easily converted into vegetative cells by the first step germination stimulation. And the heat-resistant spores are easily converted into heat-labile vegetative cells by the second-step germination process. Therefore, all the vegetative cells are killed in the third step of killing. In addition, heat-resistant spores are reduced in the first and second steps, so the sterilization condition in the third step is to sterilize the bacteria in tofu for a short time as long as it is above the temperature at which vegetative cells die, and simple heat sterilization is performed. Compared to, there is less adverse effect on the quality of tofu,
Storability is stable.

[0019]

Example 1 Silken tofu and cotton tofu (400 g each) produced by a conventional method were hermetically packaged together with water in a container,
After the center temperature reached 80 ° C. in water at 0 ° C., it was held for 30 minutes. Next, after the central temperature reached 35 ° C. in water at 35 ° C., it was held for 60 minutes, and then the central temperature reached 85 ° C. in water at 85 ° C., then held for 20 minutes for sterilization. After sterilization, it was cooled to 10 ° C. or lower with cold water and stored under 10 ° C. condition, and 15 days after storage, the general viable cell count, breaking strength, appearance and flavor of tofu were examined. The untreated tofu product is stored as control 1 after storage for 4 days, and as control 2 after reaching to 85 ° C. and sterilized only for 40 minutes. As can be seen from Table 1, the tofu according to the present invention has a better shelf life than the untreated Control 1 for both silky and cotton tofu, the number of general viable bacteria is low even after 15 days of storage, and there is no problem in appearance and flavor. There was no Further, the breaking strength of the tofu was numerically almost the same as that of the untreated control 1, and hardening of the tofu by the treatment of the example was not recognized. On the other hand, 85 ℃, 40
Tofu after storage for 15 days in Control 2 with only heat treatment for
It was suggested that the preservability is greatly influenced by the difference in the flora of the heat-resistant spores remaining after the heat treatment, since the number of general viable bacteria varies widely and some specimens have spoiled. Further, since the tofu is hardened due to the heat treatment for a longer time than this example, the breaking strength is also a high value.

[0020]

[Table 1]

[0021]

[Example 2] Silken tofu and cotton tofu (400 g each) produced by a conventional method were hermetically packed in a container together with water.
After the center temperature reached 80 ° C. in water at 0 ° C., it was held for 30 minutes. Next, after the central temperature reached 55 ° C. in water at 55 ° C., it was held for 60 minutes, then, after the central temperature reached 85 ° C. in water at 85 ° C., it was held and sterilized for 20 minutes. After sterilization, it was cooled to 10 ° C. or lower with cold water and stored under 10 ° C. condition. After 15 days of storage, the general viable cell count, appearance and flavor of tofu were examined, and the results shown in Table 2 were obtained. In addition, 4 of untreated tofu products
The storage result after one day was used as control 1. As can be seen from Table 2, the properties of the tofu were good even after storage for 15 days for both silken and cotton tofu.

[0022]

[Table 2]

[0023]

Example 3 Silken tofu and cotton tofu (400 g each) produced by a conventional method were hermetically packaged together with water in a container,
After the center temperature reached 80 ° C. in water at 0 ° C., it was held for 30 minutes. Next, after the central temperature reaches 35 ° C in water at 35 ° C, it is held for 60 minutes, then, after the central temperature reaches 55 ° C in water at 55 ° C, the temperature is kept for 60 minutes, and then to 85 ° C. After reaching, it was kept for 20 minutes for sterilization. After sterilization,
After cooling to 10 ° C. or lower with cold water, it was stored under the condition of 10 ° C., and 15 days after storage, the general viable cell count, appearance and flavor of tofu were examined.
The survey results are shown in Table 3. As can be seen from Table 3, the germination probability of heat-resistant spores in tofu is set to two stages of 35 ° C. and 55 ° C. and the holding time is 120 minutes in total, so that the germination probability is higher than that in Examples 1 and 2. It was considered that the tofu was improved, the subsequent heat sterilization effect was enhanced, and the preservability of the tofu was stable.

[0024]

[Table 3]

[0025]

The present invention is intended to improve the preservability of the tofu after packaging by heat treatment. According to the present invention, soymilk, which is a drawback of the known technique of ultrahigh temperature sterilization of soymilk, is used. There is no adverse effect of excessive heat treatment such as browning, generation of heating odor, and reduction of coagulation power, and strict control is also required to prevent secondary contamination after sterilization, which is a common problem in sterilization technology at the soymilk stage. Instead, there is an effect that the problem disappears in a normal manufacturing environment. In addition, the present invention incorporates a germination treatment step of heat-resistant spores with the tofu after packaging as an object, and makes the subsequent heat sterilization treatment more effective in a short time. Therefore, compared with the case where the tofu after packaging is simply heat-sterilized, there is no adverse effect such as hardening of tofu, browning and generation of heating odor, and the preservability of the untreated product is maintained for 15 days or more. Has the effect of improving.

[Brief description of drawings]

FIG. 1 is a process schematic diagram when the present invention is incorporated into conventional tofu production.

FIG. 2 is a schematic view of a conventional tofu manufacturing process not using the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kota Hatano 2-17-8 Mochida, Gyoda City, Saitama Asahi Food Products Co., Ltd.

Claims (3)

[Claims] 1. A method of wrapping a tofu produced by a conventional method, sterilizing the tofu spore germination stimulation step, heat-resistant spore germination step and heat sterilization step, and then cooling. The method of manufacturing tofu that can be stored for a long time. 2. In the heat-resistant spore germination stimulation treatment step, 6
Treatment in the temperature range of over 0 ° C and less than 100 ° C for 1 minute or more and 60 minutes or less. In the germination process of heat-resistant spores, treatment in the temperature range of over 10 ° C and less than 60 ° C for 1 minute or more and 180 minutes or less In the heat sterilization process, the temperature exceeds 60 ° C,
The method for producing long-term storable tofu according to claim 1, wherein the tofu is treated in a temperature range of less than 0 ° C for 1 minute or more and 40 minutes or less. 3. The method for producing long-term storable tofu according to claim 1, which is characterized by cooling to room temperature or below after refining and refrigerating.