JPH0235054A - Improved production of sterile bean curd placed in vessel - Google Patents

Abstract

PURPOSE:To obtain a sterile bean curd in high thermal efficiency without using a sterilizer while reducing time under aseptic conditions by charging respectively specified sterilized soybean milk and aseptic coagulant solution into a sterilized vessel under aseptic conditions and carrying out mixing, sealing under aseptic conditions, standing to cool and coagulation. CONSTITUTION:A sterilized soybean milk prepared by treatment at >=128 deg.C for >=1sec and cooling to 75-90 deg.C is charged into a sterilized vessel under aseptic conditions at the same time or directly after when a sterilized coagulant solution prepared by filtration of a gluconic delta-lactone aqueous solution through a bacterial filter and cooling thereof to <=20 deg.C is charged into the vessel. After mixing sealing under aseptic conditions, packing into a packing vessel, standing to cool and coagulation are carried out, thus obtaining the objective sterile bean curd excellent in flavor and quality and capable of long period storage at room temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an improved method for producing packaged aseptic tofu without using sterilizing agents. In more detail.

Continuously heat-sterilized soybean milk at 75 to 90°C and sterilized coagulant solution at 20°C or below are continuously or sequentially filled, mixed, and sealed in a sterile container under aseptic conditions. The present invention relates to an improved method for producing packaged aseptic tofu that does not use a sterilizing agent, which comprises a series of steps of cooling and curing in a packaging material without reheating.

(Prior art 1. Problems to be solved by the invention) In the conventionally developed method for continuously producing aseptic tofu in containers,
After high-temperature sterilization to maintain the sterile conditions necessary for long-term storage, the wire materials are returned to room temperature in aseptic conditions, and then each is sent to a pipeline where they are continuously mixed. , filled in sterile molded containers under aseptic conditions.
The tofu is sealed and then reheated for complete coagulation, and this is the only way to produce sterilized, shelf-stable containerized tofu.

However, these methods require cooling the sterilized soymilk to room temperature, mixing, filling, and sealing the coagulant solution at room temperature and then reheating it, resulting in a process with poor thermal efficiency, and the aseptic state after sterilization. Excessive cost and time were required for long-term maintenance.

(Means for Solving the Problems) The present inventors focused on this point, and aimed to effectively improve the thermal efficiency in the manufacturing process, and to further improve the aseptic state without reheating the coagulated tofu. Shorten retention time,
Furthermore, we conducted research aimed at developing a method for producing container-packed aseptic tofu that does not use sterilizing agents and has excellent flavor and quality, and can be stored for long periods at room temperature, and we have finally achieved this goal.

In other words, sterilized soymilk is (1) kept at as high a temperature as possible, (2) mixed with the coagulant solution at as high a temperature as possible, and (3) the coagulant solution is kept as low as possible to maintain stability. , (4) mixing soy milk and coagulant solution at high temperature to omit reheating, (5) pouring and mixing coagulant solution and soy milk simultaneously or sequentially, (6) filling, mixing, and sealing process. By carrying out the process at high temperatures, it was possible to easily maintain sterile conditions, and at the same time, it was possible to shorten the manufacturing process and manufacturing time.

(Example) Each step of the method of the present invention will be explained in detail below, and the improved effects will be specifically described.

■First step The soymilk used in the production method of the present invention is one produced by a conventional method, or one obtained by dissolving powdered soymilk in water.
In terms of the quality and economic efficiency of the tofu obtained, the soy milk solid content concentration is preferably 9 to 12% by weight.In the case of the present invention, the soy milk is sterilized in an ultra-high temperature sterilizer and cooled to a predetermined temperature. Since this cooling temperature is the coagulation temperature at which the coagulant solution is mixed and filled, an experiment was conducted to determine the cooling temperature to make tofu sufficiently firm.

Experiment (1) Powdered soy milk was adjusted to have a solid content concentration of 10% by weight, and heat sterilized at 140°C for 4 seconds.
Cooled to 0 and 90°C. Immediately, 98 g of this sterilized soy milk was poured vigorously into a container containing 2 g of a 15% by weight glucono delta-lactone aqueous solution, mixed, and then sealed.
After cooling at room temperature for 30 minutes, refrigerate.

After 24 hours, the hardness of the obtained tofu was measured at 20° C. using a card meter manufactured by Fudo Kogyo ■. The measurement results are shown in Figure 1.

From the results shown in Figure 1, the higher the cooling temperature of soymilk, the harder the obtained tofu will be, but in order to achieve sufficient hardness (30 or higher), the cooling temperature needs to be 75℃ or higher. I found out something.

Experiment (2) Next, the soymilk prepared, heat sterilized, and cooled in the same manner as in Experiment (1) was maintained at the respective temperature, and then placed in a container containing a coagulant solution under the same conditions as in Experiment (1). After pouring and mixing, seal, cool at room temperature for 30 minutes, refrigerate, and after 24 hours
The hardness of the obtained tofu was measured using a card meter at 0°C. The measurement results are shown in Figure 2.

From the results shown in Figure 2, it can be seen that when the cooling time of soy milk exceeds 30 minutes, the hardness of the obtained tofu decreases, and
It can be seen that the cooling holding temperature of "C" is the most suitable temperature range.

From the results of experiments (1) and (2), it seems that in the actual manufacturing process, the cooling temperature is maintained for approximately 30 minutes until the soy milk is sterilized at high temperature and filled into a sterilized container. It was found that a holding temperature of 75 to 90°C is suitable.

(2) Second step Glucono delta-lactone is dissolved in water in a coagulant dissolution tank, and the coagulant solution is sterilized through a sterilization filter with a pore size of 0.2 to 0.45H. in this case.

The concentration of the glucono delta-lactone aqueous solution should be as high as possible in relation to the coagulation temperature. In other words, the higher the concentration of the coagulant solution, the less the amount to be used. The change in coagulation temperature of soymilk also becomes smaller. Furthermore, mixing using the flow rate of the soybean milk to be filled and mixed becomes sufficient. However, the hydrolysis of glucono delta-lactone in an aqueous solution proceeds more rapidly as the temperature of the aqueous solution increases, so the temperature of the coagulant solution must be kept as low as possible, and it must be completely dissolved as quickly as possible. .

Experiment (3) Soy milk prepared, heat sterilized, and cooled in the same manner as in Experiment (1) was subjected to 2. l0120 and 15 dissolved and held at 30°C
The tofu was poured vigorously into a container containing 2 g of an aqueous solution of glucono delta lactone, mixed and sealed, allowed to cool at room temperature for 30 minutes, then refrigerated. The hardness was measured. The measurement results are shown in Figure 3.

From the results shown in Figure 3, it is clear that the temperature of the coagulant solution should be 20'C or less, and that the time it lasts for addition to soybean milk should be as short as possible, but there is no practical problem as long as it is within 15 minutes. Ta.

Further, the concentration of the coagulant solution is preferably 10 to 25% by weight, which is a concentration that can be dissolved in water at 20'C or less within 1 minute.

Further, as shown in FIG. 4, it can be seen that if the amount of glucono delta-lactone added as a coagulant is 0.25% or more, the resulting tofu will have sufficient hardness. Since glucono delta-lactone is expensive, it is preferable to reduce the amount of 'fA calories as much as possible, and in one experiment, 0.3% by weight was selected.

■Third step In the case of the present invention 5 Sterile soymilk and coagulant solution are mixed by injecting the coagulant solution into a sterile container in advance or at the same time, and mixing by utilizing the flow rate of the soymilk maintained at a high temperature. Use that temperature to solidify.

Therefore, unlike the general case, filling and mixing are carried out at the same time, but the containers used are completely sterilized and dried at the same time as molding from heat-resistant sheet material, or after molding and before filling. It is sufficient that the procedure is carried out in a timely manner and sterile conditions are maintained.

Further, in order to prevent the holding temperature of soymilk from being significantly lowered when the soybean milk is poured into the container, the amount of the coagulant solution used is preferably 1 to 5% by weight.

The soybean milk obtained in Experiments (1) and (2) whose cooling temperature is 75 to 90°C has ideal flavor, hardness, and storage stability (see Table 1). This proves that this process is comparable to ordinary ones.

The container used is made of a sheet material that is heat resistant enough to withstand the holding temperature of soy milk and durable against water as a medium.
Furthermore, if a pre-molded container is used, it must be sterilized before the coagulant solution is injected.

Sterilization of this container material is done with heated hydrogen peroxide,
After complete sterilization, unreacted hydrogen peroxide is completely removed in a sterile chamber and then dried.

This material is then pressure molded into sterile containers.

Filled with sterile coagulant solution and soy milk. Filling is done in a sterile chamber pressurized with sterile air, so
Complete sterility is maintained. Further, the filled container is heat-sealed with a lid material that has been sterilized using hydrogen peroxide in the same manner in the sterile chamber to completely seal the container.

■Fourth step In the present invention, soy milk is filled and mixed at 75 to 90°C, so as is clear from the results of experiments (1) and (2), there is no need to reheat it after mixing with the coagulant solution. However, soy milk completely curdles. However, in the method of the present invention, which investigated the effects of cooling temperature and time in order to completely coagulate the obtained tofu and improve its flavor, the sealed container is immediately stored in a cardboard packaging container. . According to the results of a preliminary experiment, it was found that the temperature of tofu in a packaging container containing 18 pieces filled, mixed and sealed at 90°C was 75°C or higher even 20 minutes after packaging.

Experiment (4) 98 g of soy milk prepared and sterilized in the same manner as in Experiment (1), cooled and held at 90°C was poured into a sterile container containing 2 g of coagulant solution, mixed and sealed, and then heated to 20 or 70°C. After holding the tofu for a predetermined period of time, the hardness of the tofu was measured using a card meter in the same manner as in Experiment (1). The results are shown in FIG.

From the results shown in FIG. 5, it can be seen that the hardness of the obtained tofu becomes faster and harder when the cooling temperature is higher. Also, 2
It was also found that sufficient hardness can be obtained even if the material is left to cool at 0° C. if left to cool and held for 30 minutes or more.

(Effects of the Invention) As described above, the method of the present invention is effective in controlling the cooling and holding temperature of sterilized soymilk, the concentration and holding temperature of the coagulant solution, the prior or simultaneous injection of the coagulant solution, and the filling and mixing of soybean milk based on the flow rate. , which is characterized by the fact that it does not require reheating, and therefore cannot be replaced with other methods in terms of the soy milk sterilization method, coagulant solution treatment method, container filling method, heat retention, and cooling temperature. , it becomes impossible to produce high-quality aseptic tofu in containers.

That is, the method of the present invention can be achieved only by performing all of the first to fourth steps in this order.

In addition, in the method of the present invention, soymilk that is initially heated to a high temperature for sterilization is cooled and held without being reheated, resulting in extremely high thermal efficiency, and therefore rapid production, and the equipment used can be simplified, resulting in equipment costs. It also has the advantage of significantly saving factory space.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the cooling temperature of sterilized soymilk and the hardness of the obtained tofu. FIG. 2 is a diagram showing the relationship between the holding time of sterilized soymilk at each cooling holding temperature and the hardness of the obtained tofu. FIG. 3 is a diagram showing the relationship between the waiting time after dissolving the glucono delta-lactone aqueous solution and the addition of soymilk at each dissolution/holding temperature and the hardness of the obtained tofu. FIG. 4 is a diagram showing the relationship between the absolute amount (wt%) of glucono delta-lactone added and the hardness of the obtained tofu. Table 1 shows the relationship between the cooling temperature of sterilized tofu and the flavor, hardness, and storage stability of the obtained tofu. FIG. 5 is a diagram showing the relationship between the cooling temperature after sterilized soymilk held at 90° C. is mixed with a low-temperature coagulant solution and sealed, and the hardness of the obtained tofu. Figure 1 Figure 3 95℃ Cooling temperature of soymilk ('C) Figure 2 Figure 4 Cooling temperature retention time of soymilk (minutes) Addition amount of glucono delta-lactone (%) Table 1. Procedure amendment (method) 2 , Method for producing aseptic tofu in containers with improved title of the invention 3, Relationship with the case of the person making the amendment

Claims (1)

[Claims] (1) (a) Soy milk at a temperature of at least 128°C or higher,
Continuous sterilization by holding for 1 second or more, cooling and holding at 75 to 90°C; (b) Cooling the sterile coagulant solution obtained by filtering the glucono delta lactone aqueous solution with a sterilization filter to 20°C or below.・
(c) sterilizing the soymilk held at 75 to 90°C with the sterilized coagulant solution at 20°C or lower, continuously under aseptic conditions, simultaneously or immediately after filling the coagulant solution; (d) Immediately filling the sealed container into a packaging container without reheating it and allowing it to cool and harden. A method for producing sterile tofu in a container without using a sterilizing agent, characterized by: