JPS61289850A - Production of sterilized packaged tofu - Google Patents

Abstract

PURPOSE:To obtain sterilized packaged TOFU (bean curd) having stable qualities during long-term storage, by sterilizing soybean milk under heating, adding sterilely a coagulant to it, packing it sterilely into a container and coagulating it under heating. CONSTITUTION:Soybeans from which >=45wt% soluble saccharide component is removed are ground to give soybean slurry and the slurry is heated and filtered to give soybean milk. Then, the soybean milk is sterilized underheating, blended sterilely with a sterilized coagulant and packed sterilely into a sterilized container. Then, the sterilely packed soybean milk is coagulated under heating. The soluble saccharides mean water-soluble saccharide eluted by water immersion, grinding, etc. and the total amount of them is obtained by the following method. Namely, raw material soybeans are immersed in a fixed amount of water, ground together with the immersing water, the ground mixture is filtered to give soybean milk, which is adjusted with hydrochloric acid to 4.5pH, protein is precipitated, centrifuged and the saccharide concentration of a supernatant liquid is obtained as an amount of glucose by phenol-sulfuric acid method.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a novel method for producing aseptically packaged tofu.

<Prior art> Glucono delta-lactone (hereinafter referred to as GD) is used as a coagulant for tofu.
Since the development of Tofu (referred to as L), mass production of packaged tofu has become possible. This containerized tofu was easy to manufacture and had a certain shelf life, creating a new form of distribution.

However, although mass production is possible using conventional manufacturing methods, it is impossible to produce sterile packaged tofu that can be stored for a long period of time. A method for producing aseptically packaged tofu has been proposed.

There are two main methods for manufacturing aseptic packaged tofu: one is to use sterilized soymilk and operate aseptically, and the other is to heat and sterilize the soymilk filled in a container (retort sterilization), which also serves as final coagulation. However, to obtain better quality tofu,
Although the operation is complicated, the former is better.

<Problems to be Solved by the Invention> As a method of aseptic operation using sterilized soy milk, for example, the method described in Japanese Patent Publication No. 56-23574 and No. 56-23577 is known. In any case, in order to obtain sterilized soymilk, the soymilk must be sterilized by heating it to a high temperature, and this high-temperature heating will eventually affect the quality, especially the dark color and odor of the tofu during storage. Currently, it is not possible to obtain aseptically packaged tofu with stable quality even during long-term storage.

The present inventors have investigated these problems in the production of aseptic packaged tofu and found that the above problems can be solved by using raw fζ1 soybeans from which 45% or more of soluble sugar has been removed. I learned that it can be done.

<Means for solving the problems> The present invention has been completed based on this knowledge, and has the following features:
The present invention will be specifically explained below in order of each step.

(a) Step (sugar removal, grinding treatment) The raw soybeans used in the present invention may be either whole soybeans or dehulled soybeans, and these soybeans have a soluble sugar content of 45% or more, preferably 50%, before grinding. Remove the above.

The soluble sugar content in the present invention refers to water-soluble sugar content that is eluted by immersion in water, grinding, etc., and the total amount thereof is determined by the following method.

The raw soybeans are soaked in a certain amount of water, then ground together with the soaking water, and filtered. Add soy milk to pH 4 with hydrochloric acid.
.

Soluble sugar can be removed by soaking raw soybeans in water.To remove 4-5% or more, for example, whole soybeans should be soaked at 50-60°C for 6-8 hours, and hulled soybeans should be soaked at 50-60°C for 6-8 hours. 6-8 hours at 20-30°C, 40-60°C
However, in order to suppress the oxidation odor of lipids, it is preferable to soak in a temperature range such as 40°C or higher, where phosphatase does not act. One method is to soak dehulled soybeans at 45 to 55°C for about 2 hours. Furthermore, by adjusting the p)T of the soaking water to an alkaline side (pH 8.5 to i1.o) where enzymes are less likely to work, it is possible to obtain soymilk for tofu with better quality.

Furthermore, when soluble sugars are eluted from whole soybeans or dehulled soybeans with water or hot water, it is preferable to use the endosperm of the soybean as much as possible without damaging the endosperm and other parts of the soybean in steps 1 to 1. This is because when soybeans or dehulled soybeans are crushed or crushed and their cells are broken, lipoxidase and β
- Enzyme such as glucosidase comes into contact with its substrate 1-1 Unpleasant odor and taste appear, and protein elution is promoted at the same time as sugar elution, leading to increased protein loss.

The soybeans from which 45% or more of the soluble sugar content has been removed in this way are washed with water and drained if necessary, and then put into a grinder with 2 to 4 times the amount of water and ground.

Grinding may be done at room temperature, but by grinding at 40 to 50°C, you can obtain tofu with a fine texture and at the same time suppress the effects of glypoxidase and β-glucosidase during grinding. This is preferable because it can be done.

Furthermore, during grinding, adding a small amount of monoglyceride improves the protein extraction rate. Furthermore, if a small amount of sodium ascorbic acid or tocopherol is added, oxidation is prevented, which has a favorable effect on sterilization treatment at high temperatures, and it is possible to produce tofu with a more pleasant odor.

(b) Step (Heating of Go, filtration step) Heat the Go obtained in step (a) at 80 to 110°C for
The tofu is heated for 5 minutes and then filtered, but this Jl is used for the purpose of elution or thermal denaturation of soybean protein, and is no different from the heating that is normally done during tofu production.

After heating the soybean in this manner, it is filtered by a conventional method, for example, using a filter cloth, to obtain soymilk.

(c) Step (heat sterilization step) The soybean milk obtained in step (b) is heat sterilized at a temperature of at least 130° C. for at least 1 second, preferably 1 to 5 seconds. The purpose of this step is to reduce the number of remaining spores in the soybean milk to zero, and for this purpose, a heating temperature of 130'C or higher, preferably 130 to 150'C, is required for safety.

The heating time is about 1 to 5 seconds; heating for a long time will result in soft tofu, which is not preferable.

For the heat sterilization treatment, a known sterilizer such as a plate type sterilizer or a direct heating type using steam can be appropriately used.

In addition, by homogenizing the soymilk in the heat sterilization process using a Takasho homogenizer at a rate of 200 to 500 kg/cTI, good results can be achieved in the texture of the tofu. You can reduce the generation of cards on the plate if you do so.

(d) Step (sterile filling step) A sterilized coagulant, such as GDL, is added aseptically to the sterilized soymilk obtained in step (c), either alone or in combination with a divalent metal salt. Then aseptically fill and seal in a sterile container.

Specifically, G D L is approximately 25% in the coagulant dissolving tank.
The GDL aqueous solution was dissolved in water or a 10-20% ethanol aqueous solution to a concentration of Sterilize. When a divalent metal salt such as calcium chloride, magnesium chloride, etc. is used in combination, the divalent metal salt is added and mixed in an amount of 2 to 10% with respect to the GDL aqueous solution.

In addition, GD L was sterilized by immersing it in a 75% ethanol aqueous solution, and sterilized water was added to this solution to give an ethanol concentration of 1.
A sterile coagulant solution having a concentration of 0-30%, CD I, or 25% may be prepared.

The coagulant solution thus obtained was added at 0.0% to the volume of sterilized soybean milk.
5-2.0% volume addition condition. The addition and mixing may be carried out by any method as long as it is carried out in an aseptic manner; for example, the sterile coagulant solution may be directly injected into a pipe through which sterilized soybean milk is flowing.

The sterilized soybean milk to which a coagulant has been added is aseptically filled and sealed in a sterile container. This can be done using known methods such as Japanese Patent Publication No. 56-2357.
4, No. 56-23577, and No. 56-39865 are advantageously used, and it can also be carried out by the following method.

For example, using an aseptic filling machine ABS type manufactured by Tetra Pritter, a composite paper made of paper as a base material and aluminum foil and polyethylene bonded together is sterilized with hydrogen peroxide, molded, filled and sealed to produce GDL-added soymilk. It is possible to aseptically package it in a rectangular parallelepiped container. When using a form or fill-seal type aseptic filling machine, a cup processed and molded from polyethylene resin is fed into a previously sterilized sterile chamber, and after sterilization with hydrogen peroxide, GDL-added soymilk is added. The container is packed aseptically by filling it with a lid and sealing it with a lid material sterilized with hydrogen peroxide. An example of this type is DN manufactured by Dai Nippon Printing Co.
-AP type, aseptic filling machine manufactured by Hoefliger & Kalta, etc. may be mentioned.

(e) Step (coagulation step) The sterile sealed soymilk obtained in step (d) is heated to 70 to 100°C to coagulate it. This process is similar to the coagulation process in the production of normal stuffed tofu, for example, 70 to 100
The sealed soymilk is immersed in hot water at 100°C for 20 to 60 minutes, or left in a steam-filled room at 100°C for 10 to 30 minutes to heat and coagulate the soymilk. It is then cooled and made into a product. After preheating in hot water,
It may also be solidified with steam.

As explained in detail below, the present invention includes (a) to (e)
A method for obtaining aseptic packaged tofu through a process, in which 45% or more of the soluble sugar content is removed from the raw soybeans in the conventionally known production method for aseptic packaged tofu, and by using this method, tofu with high storage stability can be obtained. This has the effect of saying.

The present invention will be explained in detail in the following experimental examples.

Experimental Example Dehulled soybeans were soaked under the conditions shown in Table 1 to remove soluble sugars.

Table 1 shows the soluble sugar removal rate (sugar dissolved in soaking water/soluble sugar in raw soybean).

After draining these soaked soybeans, wash them with water at 50°C.
Grind with hot water in a grinder (Tokushu Kika Kogyo Wave L M-8 type), and steam is immediately blown into the obtained raw go so that it becomes 100%
℃ for 0.5 minutes, cooled to 80'C, and filtered to obtain soymilk.

This soymilk was homogenized at a pressure of 400 kg/cJ, then heat sterilized at 140°C for 12 seconds, cooled, and sterilized GDL was added and mixed to a concentration of 0.3%. This was aseptically filled into a plastic container, immersed in hot water at 90°C for 40 minutes to solidify, and cooled to obtain aseptically packaged tofu.

The color and aroma of this aseptically packaged tofu were measured immediately after production and after storage at 30°C for 60 days, and the results shown in Table 1 were obtained.

As is clear from the results shown in Table 1, tofu (sample No.
Items 3 to 5) were white in color and had no history of heating. In addition, the taste and texture were good, and there was little browning or change in flavor during storage, and the product could be stored at room temperature.

In addition, as a feature of the aseptic packaged tofu according to the present invention, when it is made into boiled tofu, it does not contain any soot even after being boiled for a long time.
One example is that the texture does not change.

Examples are shown below.

Example 1 10 kg of dehulled soybeans were immersed in 50°C warm water 501,
After immersing for 1 hour while maintaining the immersion temperature at 50'C, the immersion water was removed, fresh warm water 4-01 at 50°C was added, and immersion was again carried out for 1 hour while maintaining the temperature at 50'C. (Total soaking time: 2 hours) After soaking, drain the water and add 8% of monoglyceride to this.
0, q, add 30g of sodium ascorbic acid, 5
0°C warm water4. The mixture was ground using a grinder (Model LM-S, manufactured by Tokushu Kika Kogyo) while adding Ol. The temperature of the gou during grinding was 48°C.

Immediately after grinding, steam is blown into the steam pipe installed in the grinder discharge pipe to heat the go to 100°C, and
After being held for a second, the mixture was cooled to 80°C, filtered through a pressure filter equipped with a 100-mesh sieve, and immediately degassed and cooled in a mixing tank to obtain soymilk.

This soymilk was homogenized using a high-pressure homogenizer (Model M, manufactured by Mann Ngorin) at a pressure of 4-00 kg/cl, degassed, and then sterilized using a plate-type sterilizer (Model P-20, manufactured by Alfa Laval) at a pressure of 140 kg/cl. The mixture was heat sterilized at ℃ for 2 seconds and pooled in a sterilized storage tank while cooling.

On the other hand, a 25% GDL aqueous solution was sterilized using a millibore membrane filter (SW-47 manufactured by Millibore Limited), and a coagulant solution was added thereto at a volume of 1.0% per weight of soymilk, and this mixed solution was sterilized. The mixture is brought into an atmosphere and filled aseptically into plastic containers that have been sterilized using hydrogen peroxide.
This was also sealed with a lid material sterilized with hydrogen peroxide, and this was immersed in hot water at 90°C for 40 minutes to coagulate the soymilk.
Aseptically packaged tofu was obtained.

The obtained tofu had a fine texture and good texture, and no change was observed even after storage at room temperature for 2 months.

Example 2 After dissolving 50 I of potassium carbonate (anhydrous) in 50 I of warm water at 45°C, 10 kg of dehulled soybeans were immersed (pH 10.5).
). After soaking for 1 hour and 15 minutes while maintaining the soaking temperature at 45°C, remove the soaking water and add fresh 45°C warm water 4.07
! (containing 20.9% of soda carbonate) was added and immersed for 1 hour and 15 minutes while maintaining the temperature at 45°C.

The raw soybean paste obtained by the same procedure as in Example 1 was heated to 105°C by blowing steam, held for 30 seconds, cooled to 85°C, and treated in the same manner as in Example 1. and obtained soy milk.

This soymilk was homogenized using a high-pressure homogenizer (Model M manufactured by Manton-Gaulin) at a pressure of 200 kg/ctA, degassed, and then sterilized at 130°C for 15 seconds using a plate-type sterilizer (Model P-20 manufactured by Alfa Laval). Perform heat sterilization of
Pooled into sterile storage tank while cooling.

On the other hand, GDL and magnesium chloride were sterilized by immersion in 75% ethyl alcohol, and then diluted with sterilized water to a concentration of 10% alcohol. The concentrations of GDL and magnesium chloride at this time were 30% and 10%, respectively.

This coagulant solution was added and mixed in a volume of 1.0% based on the weight of soymilk, the mixed solution was brought into a sterile atmosphere, filled into a previously sterilized plastic container, sealed, and then immersed in hot water for 90 minutes.
Preheated for 15 minutes at 100°C, then allowed to stay in a steam-filled room at 100°C for 20 minutes to heat and solidify.
Aseptically packaged tofu was obtained.

The obtained tofu had a fine texture and good taste and texture, and no change was observed even after storage at room temperature for 2 months.

Claims (1)

[Claims] (a) Step of grinding soybeans from which 45% or more of soluble sugar content has been removed to obtain go, (b) Step of heating and filtering go to obtain soy milk, (c) Step of heat sterilizing soy milk, (d) A method for producing aseptic packaged tofu, which comprises the steps of (e) heating and coagulating the sealed soy milk.