JPH05236899A - Production of soybean curd capable of long-term storage - Google Patents

Abstract

PURPOSE:To rapidly and efficiently produce packaged soybean curds and to simplify its equipment in relation to the subject method for producing soybean curd capable of long-term storage. CONSTITUTION:Soy milk obtained by the conventional method is heat sterilized at >=100 deg.C and then cooled. During the above-mentioned cooling process, the soy milk cooled to the coagulation treatment temperature of <=90 deg.C and a sterilized soy milk coagulant are charged into a package. At a time of the packaging, the soy milk is immediately subjected to coagulation treatment at the above-mentioned coagulation temperature and the package is then tightly sealed. Thus, the supply efficiency of heat is improved by utilizing surplus heat in the sterilization process and continuously coagulating soy milk. Three processes of soy milk packaging, admixture of a coagulant and coagulation of the soy milk can almost simultaneously be carried out and the production procedure can be simplified. Thereby, production of soybean curd can be done promptly.

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 tofu having a long-term storage property, and provides a tofu that can be quickly and efficiently produced in a container.

[0002]

2. Description of the Related Art Since tofu has a high water content and contains proteins and the like, it easily rots. Therefore, a bag of tofu has been developed in which a bactericidal agent is added to suppress rot. Therefore, safe and long-term storable tofu without the addition of a bactericide is demanded because its properties are pointed out. As a conventional technique of long-term shelf-life tofu containing no germicide, there is one disclosed in Japanese Patent Publication No. 56-23574, and its manufacturing method is as follows.

That is, (1) soybean milk obtained from soybean by a conventional method is sterilized by holding it at a temperature of 128 ° C. or higher for 1 second or longer, (2) once cooled to room temperature, and (3) this room temperature. Mix the sterilized soy milk cooled to and the glucono delta lactone aqueous solution aseptically filtered with a Millipore filter in a sterile mixing tank,
(4) Transfer the mixed solution of soy milk and a coagulant to a filling machine, continuously fill the mixed solution while aseptically forming a container from a heat-resistant and water-resistant sheet-shaped material, and It is sealed and (5) soymilk is heated and coagulated under the conditions of a heating temperature of 70 to 95 ° C. and a heating time of 20 to 60 minutes to produce tofu in a container.

[0004]

This tofu of the prior art can be stored at room temperature for about 2 months without the addition of a bactericide, but soy milk is sterilized, cooled to room temperature, and heated and coagulated again. It is produced according to the procedure. Since this conventional system is a system in which soy milk and a coagulant are mixed in an aseptic mixing tank and transferred to a filling machine, as described in the publication, soy milk is preliminarily stored at a temperature of 20 ° C. or lower at room temperature. This is to prevent solidification in the tank by cooling it to a smooth pipe transfer to the filling machine.

As a result, in the prior art, after the sterilization step, at least four steps of cooling to room temperature, mixing soybean milk with a coagulant, filling a container and heating and coagulating soymilk are required. Therefore, by incorporating a mixing tank, a water tank for heating and solidification, etc., the production equipment becomes complicated and the production cost rises. Further, in the conventional method, since the soymilk temperature is raised and lowered, there is much waste of heat supply, and production loss occurs due to the time required for raising and lowering the temperature. An object of the present invention is to efficiently produce long-term storage tofu.

[0006]

The present inventor has conceived that the high temperature of sterilization treatment is used for heating and coagulating soymilk, and completed the present invention. That is, the present invention 1 is a soy milk obtained by a conventional method, which is heat-sterilized at a temperature of 100 ° C. or higher at an ultrahigh temperature for a short time, cooled, and in the cooling process, soy milk whose temperature is lowered to a coagulation temperature of 90 ° C. or lower and aseptic treatment A soymilk coagulant mixed with a soymilk coagulating agent, which is a method for producing a long-term preservative tofu characterized in that the soymilk is coagulated at the coagulation temperature at the same time as filling the container, and the packaging container is sealed. .. Invention 2 is
In the present invention 1, the soy milk coagulation temperature is 50 ° C. or lower, and the soy milk coagulant is an acid-based coagulant such as lactic acid or malic acid, or a divalent metal salt-based coagulant such as magnesium chloride or calcium sulfate. It is characterized by being.
The present invention 3 is characterized in that, in the above-mentioned present invention 2, after the packaging container is sealed, the solidified tofu is kept warm to be aged.

[0007] The soybean milk refers to a conventional product such as one obtained by grinding soybeans and extracting with hot water, commercially available dry soybean milk powder, and one prepared by adding separated soybean powder to water. If the heating temperature is too high, the aroma of soy milk may escape, or the coagulability of tofu may decrease, but conversely, at low temperature and for a short time, the heat-resistant bacteria are not sufficiently killed. Therefore, the heating is performed, for example, at 120 ° C. for several minutes or at 128 ° C. for 1 second or more as in the conventional technique. The sterilization treatment is, for example, continuous sterilization using an ultra-high temperature sterilizer (hereinafter referred to as UHT sterilizer) (either an indirect heating method using a plate or a direct heating method using steam), batch sterilization using a tank, or these Can be used together. The cooling after the heat sterilization treatment may be forced cooling or standing cooling, but it is preferable to shorten the cooling time by forced cooling with a cooler. Since it is important for the cooling process to properly pass through the coagulation temperature range of soymilk, it is preferable to perform gentle cooling at least from the point of time when the temperature is close to this temperature range. The aseptic treatment of the soymilk coagulant is, for example, aseptic filtration using a micropore filter.

As the soymilk coagulant, bitter juice (magnesium chloride, etc.), sushi powder (calcium sulfate), divalent metal salts such as magnesium sulfate, monobasic calcium phosphate, or gluconodelta lactone is used alone or Combined.
However, for example, when the above-mentioned divalent metal salt-based coagulant and acid-based coagulants such as lactic acid, malic acid, citric acid and their salts are used, soy milk is coagulated relatively quickly even under low temperature heating of 50 ° C or lower. it can. The coagulation treatment means that the soy milk is heated and coagulated by utilizing the heat energy supplied in the heat sterilization step without newly heating from the outside in the coagulation process,
Soy milk is filled in a packaging container and solidified at the same time. In the case of filling the packaging container, for example, sterilized soy milk and aseptically treated coagulant are simultaneously transferred by pipe transfer, or if they are mixed in the packaging container with a time difference (that is, the coagulant is first added to the container (liquid, If fine powder is added] and then soy milk is pressure-injected, both can be efficiently and forcibly stirred. However, when the coagulant is glucono delta lactone, etc., a preliminary milk storage tank for contacting the coagulant and soy milk with the coagulant is arranged above the soybean milk filling machine described later, and this spare tank is used for multiple filling machines. There is no problem even if the container is dropped and distributed (batch type or continuous type) to fill the container.

The above packaging container has a proper sealing property, durability,
It is required to have gas barrier properties, and it does not matter whether it is a pack container or a bag container (blow container). The blow container is filled with soy milk and a coagulant in a mold or into a filling chamber while the container is blow molded from a synthetic resin pellet made of polyethylene, polypropylene, polystyrene or the like, or a sheet material. And the like, for example, by improving a commercially available filling machine for blow tofu production to fill a sterile blow container immediately after injection in a sterile atmosphere. The above-mentioned pack filling is, for example, using a commercially available filling machine, heat-sealing a multi-layered sheet-shaped container material obtained by laminating polyethylene foil, polyethylene, etc. into a bag shape, and then filling soymilk in a sterile room. It does not matter if it is molded by pressing into a rectangular parallelepiped pack, or the resin sheet for the container body and the resin sheet for the lid are separately supplied to the filling machine by a foam seal type aseptic filling machine.

On the other hand, soy milk is coagulated at 90 ° C. or lower. In this case, generally, as the temperature approaches 90 ° C., the solidification rate increases and the productivity increases, but on the other hand, the low temperature solidification has the advantage that the heat resistance of the packaging container is not strictly required if the water resistance is sufficient. For example, when low-temperature solidification is performed at 50 ° C or lower,
Compared with heat solidification at around 90 ° C., there is less risk of peeling or breakage of the adhesive portion of the container, and the structure of the container can be simplified by reducing the number of laminated layers. In the low temperature coagulation treatment, an aging step may be added in which the temperature of the sealed container is maintained at the coagulation treatment temperature to promote tofu formation (homogeneous coagulation). For the aging, the filled container is stored in a heat-retaining box or is treated by blowing hot air at a predetermined temperature.

[0011]

[Action]

(1) The production procedure of the prior art is heat sterilization step → room temperature cooling step → mixing step of soy milk and coagulant → container filling step → soy milk heat coagulation step, whereas the production procedure of the present invention is heat sterilization step → Container filling / mixing (in the cooling process from heat sterilization)
This is the soy milk coagulation process. That is, by utilizing the excess heat in the cooling process from the heat sterilization process (in other words, under the coagulation treatment temperature in the return process from the heat sterilization process) soymilk is rapidly heated and coagulated, like the prior art, It is possible to omit the trouble of raising and lowering the temperature of once cooling the soy milk to room temperature and then heating and coagulating it. Further, the present invention, the mixing step of soy milk and a coagulant, the step of filling the container, the heating and solidifying step of the soy milk are simultaneously performed, and at the same time the container is filled (the filling container also serves as a mixing container) coagulates. Since soy milk under the processing temperature is mixed with a coagulant and starts heating and coagulation, outside the soy milk container filling step, as in the prior art,
It is not necessary to separately provide a tank for mixing soy milk and a coagulant or a water tank for heating and coagulating the soy milk filling.

(2) By selecting a divalent metal salt-based coagulant or an acid-based coagulant such as lactic acid, tofu can be rapidly coagulated even at a coagulation treatment temperature of 50 ° C. or lower. In this low-temperature coagulation, foaming of soy milk is suppressed and smooth inclusion of air bubbles in tofu is prevented. Further, with a magnesium salt-based coagulant such as bitter juice or a calcium salt-based coagulant such as sushi powder, it is difficult to uniformly coagulate soymilk when the coagulation temperature is high, soybean milk solids and water are separated. Homogeneous tofu can be easily obtained by low temperature treatment at 50 ° C or lower. In particular, it is said that “nigari tofu” obtained from a magnesium salt-based coagulant has the best taste, and even if lactic acid, bitter soup, sushi powder, etc. are used together, the taste unique to soybeans can be utilized to improve the taste mildly.

[0013]

【The invention's effect】

(1) The soy milk is given heat energy for sterilization by ultra-high temperature heating, and the soy milk is solidified in the cooling process of sterilization heating. Therefore, when looking at the production of tofu from the aspect of heat supply, room temperature cooling after sterilization and reheating for soymilk coagulation as in the prior art are not necessary, and basically only heating in the sterilization process is required. Therefore, there is no waste of heat supply, and the heat supply system can be simplified. Also, there is no loss of production time due to raising or lowering the temperature. (2) The soy milk filled in the packaging container is brought into contact with the coagulant to coagulate, and the container filling, mixing, and coagulation are performed at the same time. The production equipment and production procedure can be simplified. Especially 70 ℃
At a normal coagulation treatment temperature above a strong level, the tofu in the container can be immediately produced by filling after the sterilization treatment, so that the tofu production rate can be greatly improved. (3) Generally, in the production of tofu, it is necessary to leave the soy milk that has started to solidify in order to homogenize the tofu structure.
(Especially remarkable in the case of a divalent metal salt-based coagulant). Therefore, in the above-mentioned conventional method of filling the container with the sterilized soymilk and the coagulant mixed in advance in the mixing tank, if the coagulant is bitter soybean powder or the like, the soymilk is mixed even when cooled to room temperature. At the same time, coagulation begins, making pipe transfer for container filling difficult. Therefore, in the above-mentioned conventional technique, it is necessary to specify the coagulant as glucono delta lactone, but in the present invention, the filling container also serves as a mixing tank, so there is an advantage that the coagulant is not restricted.

(4) High-temperature solidification When heated, there is a risk that the bonded portion of the pack container will peel off and cause water leakage, for example, so it is necessary to develop a special adhesive.
When the low temperature coagulation treatment is performed at 0 ° C. or less, the seal portion does not peel even with a normal adhesive. Therefore, the sealing property of the packaging container can be enhanced to reduce the production cost of the container, and the structure of the packaging container can be simplified by relaxing the heat resistance requirement. (5) When the low temperature coagulation treatment is performed as in the above (4), the commercial value can be increased without the inclusion of bubbles in the tofu during the heat coagulation.
In addition, the coagulation conditions affect the quality of tofu, and if the amount of coagulant added is constant, the tofu becomes harder as the coagulation temperature rises, but if the coagulation treatment is performed at a low temperature as in (4), the tofu tissue becomes soft. You can make the texture mellow. Moreover, if the soy milk concentration is constant, the taste of tofu depends on the coagulant,
Using a magnesium salt-based coagulant, it is possible to obtain delicious bittern tofu, and tofu with excellent taste can be obtained by using lactic acid, bitter soup, sushi powder, etc. in combination. (6) Since the tofu in this container is produced by mixing soymilk that has been sterilized at ultra-high temperature for a short time and a coagulant that has been sterilized, it can be stored at room temperature for 3 to 4 months without using a bactericide. It is possible.

[0015]

【Example】

<Example 1> Soybeans obtained by washing and grinding soybeans and extracting with hot water were adjusted to a solid content of about 10% in a solid content adjusting tank,
After transferring to a UHT sterilizer with a pump and sterilizing at a high temperature for a short time at 127 ° C for 6 to 7 minutes, cool the soymilk at a high temperature to a low-temperature coagulation treatment temperature of about 50 ° C and then paper. The soybean milk was transferred to the upper part of the pack type soybean milk filling machine (in this case, the soybean milk was in the cooling process from the sterilization process and was not heated from the outside after the sterilization process). In addition, a lactic acid-based coagulant mainly composed of lactic acid, calcium sulfate or the like for low temperature treatment is aseptically filtered through a micropore filter, and pipe-transferred together with the above-mentioned sterilized soymilk while maintaining the temperature at 50 ° C., and a soymilk filling machine is used for container. Each was poured and filled. That is, while molding a sterile bag from a laminated sheet material using a pack type filling machine (manufactured by Nippon Tetra Pak Co., Ltd.), a coagulant liquid and sterilized soy milk are simultaneously pressure-injected with the vertical movement of the pipe inlet.
It was filled, quickly sealed and stamped into a rectangular parallelepiped pack container. In the pack container, the soybean milk under the coagulation treatment temperature of 50 ° C. and the coagulant come into contact with each other to immediately start coagulation,
It solidified into tofu in about 5 minutes. Next, a plurality of pack containers were collected in a basket-like form, and stored in a heat-retaining container under conditions of slightly less than 50 ° C. and 30 minutes for aging, and then discharged and allowed to cool to obtain a tofu packaged in a pack container.

In filling the soybean milk with the container, the soybean milk and the coagulant were simultaneously pressed while the pipe inlet was moved shallowly with respect to the container, so that the coagulant was well forcibly stirred into the soymilk to homogenize the composition of the coagulum. I was able to The concentration of the lactic acid-based coagulant added to the soymilk was a little over 0.7 wt%. The composition of the lactic acid-based coagulant is as follows: lactic acid 25 wt%, sodium malate 10
The content was wt%, calcium sulfate 55 wt%, and magnesium chloride 10 wt%. The sheet material of the container was a three-layer sheet having an inner layer of polyethylene and a cardboard layer coated with wax with an aluminum foil layer interposed. The soy milk is 127 ° C
Although the sterilization was performed at the heating temperature of 1, the heat sterilization may be performed at a temperature of 110 ° C. by a heat shock method of about 3 times. (1) Properties of Tofu by Container Filling and Simultaneous Coagulation Method As described above, the tofu coagulated at low temperature at 50 ° C. had a soft texture and good texture without lack of elasticity. The tofu tissue is even and uniform in coagulation,
No inclusion of air bubbles in the tissue was found. In addition, since a lactic acid-based coagulant was used, the scent unique to soybeans was retained, and it had a mellow taste and a rich flavor. (2) Long-term storage stability test Tofu in this container and commercially available tofu (with a bactericide added) were stored at room temperature and observed as a result of aging. As a result, the commercially available product had a slight sour taste and lost flavor after 1 month. In addition, the surface of the tofu turned pink and the occurrence of syneresis was also observed. On the other hand, the tofu of the present invention did not change in taste and flavor for about 3 months, and there was no problem in texture such as elasticity and smoothness.

Example 2 In this example, different from Example 1 in which sterilized soybean milk introduced from each transfer pipe to an aseptic filling machine and the coagulant were simultaneously filled in a container, the time difference between the coagulant liquid and the soymilk was obtained. It was configured to be provided and filled. That is, soybean milk that had been heat-sterilized under the same conditions as in Example 1 was cooled to 80 ° C (to 90 ° C) with a cooler. In addition, aseptically processed aqueous solution of glucono delta lactone (concentration of coagulant is 1 wt
%) And the above-mentioned sterilized soy milk that has been maintained at a temperature of 80 ° C (to 90 ° C) are separately pipe-transferred, and polyethylene pellets are blow-molded into a container by each aseptic filling machine, and the coagulant liquid is first prepared in the mold. To store at the bottom of the container,
Then, sterilized soymilk was injected under pressure to fill the container, and the container was quickly sealed while immediately solidifying the soymilk that was in contact with the coagulant, and the container-containing tofu was produced without the aging step.

In Example 2, the soy milk solidified into tofu almost instantaneously when the container was filled and the aging step was omitted, so that the tofu production efficiency was extremely high. In addition, the soybean milk was pressed into the coagulant liquid stored in the bottom of the container, so that the mixed liquid could be efficiently and forcibly stirred, and thus tofu with high homogeneity was obtained.

Claims (3)

[Claims] 1. Soymilk obtained by a conventional method is sterilized by heating at a temperature of 100 ° C. or higher for an ultrahigh temperature for a short time, cooled, and in the cooling process, soymilk whose temperature is lowered to a coagulation temperature of 90 ° C. or lower and aseptically processed soymilk. A method for producing long-term shelf-life tofu, which comprises mixing a coagulant with a packaging container, filling the container with the coagulating agent, and coagulating soymilk at the coagulation temperature, and sealing the packaging container. 2. The soy milk coagulation temperature is 50 ° C. or lower, and the soy milk coagulant is an acid coagulant such as lactic acid or malic acid or a divalent metal salt coagulant such as magnesium chloride or calcium sulfate. The method for producing long-term preservable tofu according to claim 1, wherein 3. The packaged container is sealed, and then the solidified tofu is kept warm for aging.
The method for producing a long-term shelf-life tofu described in.