JPH09187243A - Process for keeping freshness of bean curd - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the retention time of the freshness of bean curd by a safe process. SOLUTION: In an electrolysis tank having an anode chamber and a cathode chamber partitioned by a diaphragm having ion permeability, an aqueous solution of an alkali chloride compound is electrolyzed to produce an anode water having an oxidation-reduction potential of 1000-1200mV and pH of 2.0-3.0 in the anode chamber. Bean curd is placed in an adequate container, and the anode water is poured into the container in such an amount that the bean curd is dipped in the water. The opening of the container is covered with a food packaging film, etc., to intercept the inner materials from the outer atmosphere, and the container is allowed to stand. The proliferation of microorganisms on the surface of the bean curd is suppressed by the anode water, and the suppressing effect lasts for several days because of the interception from the outer atmosphere. Since the anode water is converted into water, the anode water is harmless.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for maintaining quality of tofu that can be retained without impairing the taste, appearance, etc. of tofu.

[0002]

2. Description of the Related Art Tofu is one of the foods that is indispensable in daily eating habits because it has a high nutritional value, but the cell membrane is destroyed in the process of miniaturizing the raw soybean, and the protein is suitable for the growth of various bacteria Shredded into small pieces, the above bacteria rapidly propagate in the presence of water. Therefore, the so-called poor shelf life is a drawback. Tofu is usually sold, purchased, and eaten on the date of manufacture, but when it is stored until the next day, it is generally refrigerated at both retail stores and homes. However, this refrigerated storage is limited to a few days at the most, and it is the actual situation that even such storage is difficult especially in the summer when the progress of decay is fast.

Therefore, in retail stores, not only tofu that has remained unsold and deteriorated in quality, but even if there is no deterioration in quality, the products on the next day or the day after the second day of manufacture tend to lose sales, and are discarded without being sold. I have to do it. On the other hand, even if the consumer does not eat one or two days after purchase for some reason, he / she must discard it for safety. For safety reasons,
In either case, it is uneconomical and wastes agricultural resources. These problems are almost negligible if we consider the fact that tofu is eaten nationwide and internationally in recent years, and expanded to a global perspective. Absent.

[0004]

As one of the methods for extending the freshness retention period of tofu, it is possible to add a preservative and increase the amount thereof. However, the problems of carcinogenicity and allergic diseases caused by additives have become known, and it is now easy to apply natural foods containing no or no additives as much as possible. The use of different preservatives is undesirable.

Therefore, the present invention provides a method for keeping freshness of tofu which can be retained for a long period of time without using additives such as preservatives without impairing the freshness such as taste and appearance of tofu and safety. The purpose is.

[0006]

In order to solve the above-mentioned problems, the method of keeping freshness of tofu according to the present invention comprises, as described in claim 1, an aqueous solution of an alkali chloride compound separated by an ion-permeable membrane. In an electrolyzer having an anode chamber and a cathode chamber, the tofu is immersed in the anode water (hereinafter referred to as “oxidation potential water”) produced in the anode chamber and isolated from the external atmosphere. It is characterized by saving in a state.

Further, in order to solve the above-mentioned problems, the method of keeping freshness of tofu according to the present invention is, as described in claim 2, the oxidation potential water and the oxidation reduction potential of 1000 to 1200.
It is characterized by having a mV and a pH of 2.0 to 3.0.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for maintaining freshness of tofu according to the present invention, tofu is treated with oxidizing potential water, which is obtained by electrolyzing an aqueous solution of an alkali chloride compound. For example, JP-A-6-246265
It can be manufactured by the method described in the publication. Next, an example thereof will be described with reference to FIG. FIG.
It is a schematic sectional drawing of the electrolytic cell for obtaining oxidation potential water.

First, an aqueous solution of an alkali chloride compound, for example, an aqueous solution of sodium chloride, is supplied from the supply port 20 of the electrolytic cell 10 to the anode chamber in which the anode 18 is installed and the cathode chamber in which the cathode 16 is installed. Both chambers are ion-permeable diaphragm 14
Are separated by Next, start energizing from the electrodes,
Make electrolysis. As a result, electrolyzed water, that is, cathode water is generated in the cathode chamber and oxidation potential water (anode water) is generated in the anode chamber. Then, by extracting the generated water inside the anode chamber, the oxidation potential water used in the present invention can be obtained.
Reference numeral 8 is an ORP meter for measuring the redox potential, and 9 is a pH meter. Reference numeral 22 is a discharge port on the cathode chamber side. In addition to sodium chloride as an alkali chloride compound,
Potassium chloride, potassium chlorate, sodium chlorate, etc. can be used. In the figure, the continuous electrolytic cell in which the alkali chloride compound continuously flows in from the supply port 20 is shown, but as a so-called batch type electrolytic cell in which a valve is provided in front of the supply port 20 to intermittently supply water. Good.

In order to obtain oxidation potential water having an oxidation-reduction potential of 1000 to 1200 mV and a pH of 2.0 to 3.0 using the electrolytic cell 10 as shown in FIG. 1, sodium chloride is added to raw water. 3 to 10% sodium chloride aqueous solution is mixed with the mixture, and a constant amount of this mixed solution is continuously supplied to the raw water, that is, an aqueous solution containing an electrolyte maintained at a constant concentration is supplied per hour via the supply port 20. A fixed amount is supplied into the electrolytic cell 12. At this time, the energization amount increases as the electric conductivity of the aqueous solution increases, and strong electrolysis is performed. The oxidation potential water obtained by this electrolysis is discharged from the water discharge port 24, and this is measured by the ORP meter 8 or the pH meter 9 and the desired value of water discharge is used. The current flowing through the electrolytic cell 10 varies depending on the nature of the raw water, the amount of the alkali chloride compound mixed in, the shape of the electrolytic cell 10, etc., but these are appropriately controlled by a control circuit (not shown).

The oxidation-potential water thus obtained has an excellent effect of suppressing the growth of microorganisms, and therefore has an oxidation-reduction potential of about 1000 to 1200 mV and a pH of 2.0.
It is preferably about 3.0.

The treatment of tofu with oxidation potential water is carried out by immersing all or part of the tofu in oxidation potential water while being shielded from the external atmosphere. As the processing method, for example, the following method can be applied. First,
The tofu is placed in a suitable container and then the oxidizing potential water is poured in an amount such that the tofu is preferably completely immersed. Of course, this procedure can be reversed. Further, at this time, it is preferable to inject the oxidizing potential water to the extent that it overflows from the container so that there is no space in the container. After that, the opening of the container is sealed with a non-breathable material such as a lid and a food packaging film to shield it from the external atmosphere, and then allowed to stand. This may be left at room temperature, and may be left at a low temperature such as in a refrigerator, if necessary. A polyethylene or polypropylene film can be used as the food packaging film, but a polyvinylidene film is preferable.

[0013]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Production Example 1 Oxidizing potential water was produced by the electrolytic cell 10 as shown in FIG. The aqueous solution of the alkali chloride compound was a mixture of 100 liters of tap water and 1 liter of 10% saline. Also, electrolysis is 6V,
It carried out on the energization conditions of 30A. By this method, oxidation potential water having a redox potential of 1150 mV and a pH of 2.6 was obtained.

Example 1 and Comparative Examples 1 to 3 Four commercially available cotton tofu (using magnesium chloride as a coagulant and a surfactant as a defoaming agent) were placed in four 1-liter containers, one by one, The oxidation potential water of Fig. 1, respectively
100 ppm aqueous sodium hypochlorite solution (Comparative Example 1)
Alternatively, tap water (Comparative Example 2) was poured until the tofu was completely immersed and near the edge of the container. Moreover, nothing was injected into the remaining one container (Comparative Example 3). Then, the mouth of the container was completely covered with a commercially available film for food packaging (polyvinylidene laminated polyethylene), and the inside of the container was shielded from the external atmosphere. In that state, it was left indoors at 25 ° C. for 7 days, and the change with time was observed.

As a result, no change in appearance was observed in the tofu of Example 1 even after 7 days, and when tasted by seven food panelists, no change in taste was observed. Was confirmed. The tofu of Comparative Example 3 was apparently spoiled after about 1 day. The tofu of Comparative Example 1 was confirmed to be turbid in water after a lapse of about 1 day, and the tofu surfaced after a lapse of about 5 days. The tofu of Comparative Example 2 showed no change in appearance, but swelling of the food packaging film was observed due to the generation of gas.

Oxidizing potential water used in the present invention has the property of deactivating by reacting with proteins. Therefore, in Example 1, the oxidizing potential water is deactivated after contact with tofu and becomes mere water. Therefore, it is completely harmless. On the other hand, when the oxidation potential water comes into contact with tofu, the growth of microorganisms attached to the surface is suppressed, and thereafter, the microorganisms are kept in a sealed state, so that the inhibitory effect is continuously retained. Therefore, in Example 1, excellent results were obtained as compared with Comparative Examples 1 to 3.

[0018]

According to the method for maintaining freshness of tofu of the present invention,
With a simple method, the quality of tofu can be maintained for several days to a week. Further, the oxidation potential water used in the present invention is harmless because it changes to simple water after contact with tofu. With the method of maintaining freshness of tofu according to the present invention, it is possible to secure a sale date and a period from the purchase date that can be sold and can be consumed to a certain extent longer than before. And contribute to effective use of agricultural resources.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view for explaining a method for producing oxidation potential water.

[Explanation of symbols]

 8 ORP meter 9 pH meter 10 Electrolyzer 14 Ion permeable diaphragm 16 Cathode 18 Anode 20 Supply port 22 Discharge port 24 Discharge port

Claims (2)

[Claims] 1. A tofu is dipped in an anode water obtained by electrolyzing an aqueous solution of an alkali chloride compound in an electrolytic cell having an anode chamber and a cathode chamber separated by an ion-permeable diaphragm. A freshness-preserving method for tofu, which is characterized by storing in a state of being shielded from the external atmosphere. 2. The redox potential of the anode water is 1000.
The method for keeping freshness of tofu according to claim 1, wherein the method is to 1200 mV and pH is 2.0 to 3.0.