JPH0153029B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel method for producing aseptically packaged tofu. Since the development of gluconogeltalactone (hereinafter referred to as GDL) as a coagulant for tofu, 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 aseptic tofu that can be stored for a long period of time. A manufacturing method has been proposed. There are two main methods for producing 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 a final coagulation process. To obtain tofu of better quality, the former method is better, although the operation is more complicated. However, even with this method, the quality of tofu tends to be inferior to that of regular tofu. As an aseptic method using sterilized soy milk, for example,
The methods described in No. 23574 and No. 56-23577 are known, but in any case, in order to obtain sterilized soymilk, the soymilk must be sterilized by heating it to a high temperature. This causes the proteins inside to become insolubilized, resulting in a negative impact on the texture and texture of the tofu.
At present, it is not possible to obtain aseptically packaged tofu that has the same quality as regular tofu. By the way, the present inventors first heated the soaked soybeans at 40 to 60℃.
The company applied for a patent based on the knowledge that the soybean paste obtained by grinding the soybeans produces significantly less foaming when heated for purposes such as protein extraction and thermal denaturation. Furthermore, various studies were conducted on the grinding conditions, and surprisingly, the soybean milk obtained by grinding soaked soybeans at 40 to 50℃ and then filtering was superior to the soymilk obtained by grinding at room temperature or at high temperature. As a result, we obtained the knowledge that the insolubilization rate of protein in soymilk is low, and aseptically packaged tofu produced using this soymilk has a fine texture and excellent texture. The present invention was completed based on such knowledge, and it is a great invention that contributes to improving the quality of aseptically packaged tofu. The present invention will be specifically explained below in order of each step. (a) Process (grinding treatment) First, whole soybeans or dehulled soybeans are soaked in water to swell. Soaking is the same as the usual method; for example, the soybeans are soaked in water at room temperature in an amount about four times the weight of the soybeans for 16 to 20 hours. The soaked soybeans thus obtained are ground at a temperature of 40-50°C. This can be done by, for example, charging soaked soybeans into a grinder together with warm water at 45 to 55°C in an amount of 4 to 6 times the weight of the soybeans. In short, any method may be used as long as it maintains a temperature of 40 to 50°C during grinding. (b) Process (heating of go and filtration process) The go obtained in step (a) is heated at 80 to 100℃ and then filtered, and this is for the purpose of elution of soybean protein or heat denaturation. There is no difference from the heating that is done during normal tofu production. Kure obtained by normal grinding foams violently when heated and requires the addition of an antifoaming agent, but the Kure used in the present invention does not foam much and does not require the addition of an antifoaming agent or only uses a small amount of it. is sufficient. An experimental example regarding this foaming is shown below. Experimental example 1 Whole soybeans were soaked in 4 times the volume of tap water at room temperature for 16 hours, then taken out of the soaking water, and poured with water or hot water in an amount of 5 times the volume per raw soybean at the temperature shown in Table 1. In addition, Go was obtained by grinding using a tabletop homogenizer (model HB, manufactured by Nippon Seiki Seisakusho) while keeping the temperature constant during grinding by cooling or heating the outer wall of the grinding container. The obtained soybean paste was placed in a 500 ml beaker with a scale of 50 ml, and heated in boiling water at 98°C for 3 minutes, and the foaming during heating was measured. The results are shown in Table 1.

[Table] Shown as +total amount of bubbles.
After heating the soybean in this manner, it is filtered by a conventional method, for example, using a filter cloth, to obtain soymilk. (c) Process (heat sterilization process) The soymilk obtained in step (b) is heated to at least 130℃ or higher for 1 hour.
Heat sterilize for at least 1 second, preferably 1 to 5 seconds. The purpose of this step is to eliminate residual spore bacteria in the soymilk, 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. With plate-type sterilizers, cards (scale) adhere to the plates depending on the concentration of soymilk and the sterilization temperature, making it difficult to operate continuously for long periods of time.
Although the protein concentration of soymilk is limited to 4.5%, the soymilk of the present invention has an extremely low protein insolubilization rate even when subjected to high-temperature heat treatment, as is clear from Experimental Example 2 described below. Therefore, adhesion of cards to the plate is hardly observed, and a plate-type sterilizer can be used more advantageously. By homogenizing the soymilk before the heat sterilization process using a high-pressure homogenizer to approximately 200 to 500 kg/ ^cm2 , it will give good results for the texture of tofu. You can generate fewer cards upwards. Experimental Example 2 Whole soybeans were soaked in 4 times the amount of tap water at room temperature for 16 hours, then taken out of the soaking water, and poured with 5 times the amount of water or hot water per raw soybean at the temperature shown in Table 2. 95 millimeter of the obtained go
After heating at ℃ for 1 minute, the mixture was filtered through a filter cloth to obtain soymilk. The protein concentration of soy milk is 5.3% (solids concentration
10%). Each of these soy milks was heated at 130℃ in a plate-type sterilizer.
Heat sterilization was performed for 5 seconds, and the protein insolubilization rate was measured, and the results shown in Table 2 and FIG. 1 were obtained. As is clear from Table 2 and Figure 1, at 40°C and
The protein insolubilization rate after heat sterilization of soybean milk obtained by grinding at 50°C was extremely low.

[Table] After adding 1% volume of a 25% aqueous solution of GDL to each sterilized soymilk, the container was filled and sealed, and the resulting tofu was immersed in hot water for 30 minutes to solidify. When observed, samples 3 to 4 (40
The sample (ground at ~50°C) was finer and more textured than other samples, and was much better. In order to clarify this effect, sample 1, sample 4,
After staining the cross section of the tofu obtained from sample 7 with an alkaline phenol reagent, a 16x enlarged photograph was taken using a stereomicroscope. These are shown in Figure 2 (Sample 1) and Figure 3.
(Sample 4) and FIG. 4 (Sample 7). By comparing Figures 2 to 4, it can be clearly understood that the texture of tofu produced by the method of the present invention is superior to that of other samples. (d) Process (aseptic filling process) A sterilized coagulant, such as GDL, alone or in combination with a divalent metal salt is added and mixed aseptically to the sterilized soymilk obtained in step (c), and the mixture is placed in a sterile container. Aseptically fill and seal. Specifically, GDL is approximately 25% in the coagulant dissolving tank.
Dissolve it in water or a 10-20% ethanol aqueous solution to a concentration of 0.3-1%.
The GDL aqueous solution is sterilized by passing it through a Millipore membrane filter (manufactured by Millipore Limited) at a flow rate of /min. Divalent metal salts such as calcium chloride,
When using magnesium chloride etc. in combination, GDL
Divalent metal salt is added and mixed in an amount of 2 to 10% based on the aqueous solution. Alternatively, GDL may be sterilized by immersing it in an aqueous solution of about 75% ethanol, and sterilized water may be added thereto to prepare a sterile coagulant solution with an ethanol concentration of 10 to 30% and a GDL concentration of about 25%. The thus obtained coagulant solution is added and mixed in an amount of 0.5 to 2.0% based on the volume of sterilized soymilk. Any method of addition and mixing may be used as long as it is done aseptically.
For example, a sterile coagulant solution may be injected directly into a pipe through which sterilized soy milk is flowing. The sterilized soymilk to which the coagulant has been added is aseptically filled and sealed in a sterile container. This can be done using known methods such as
The methods disclosed in Japanese Patent Nos. 56-23574, 56-23577 and 56-39865 are advantageously used, and the method can be carried out as follows. For example, aseptic filling machine AB8 manufactured by Tetrabrik
Using a mold, GDL-added soymilk can be packaged aseptically in a rectangular parallelepiped container by sterilizing a composite paper made of paper as a base material and laminating aluminum foil and polyethylene with hydrogen peroxide, molding, filling and sealing. It is. In addition, when using a foam/fil-seal type aseptic filling machine, processed polyethylene resin is filled into a pre-sterilized sterile chamber.
A molded cup is supplied, sterilized with hydrogen peroxide, filled with GDL-added soymilk, and sealed with a lid material sterilized with hydrogen peroxide to aseptically package the cup. Examples of such types include the DN-AP model manufactured by Dainippon Printing Co., Ltd. and the aseptic filling machine manufactured by Hoefliger & Calk. (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 regular bagged tofu, and for example,
Soybean milk is heated and coagulated by immersing the sealed soymilk container in ~100℃ hot water for 20 to 60 minutes, or by leaving it in a 100℃ steam-filled environment for 10 to 30 minutes. It is then cooled and made into a product. In addition, after preheating in hot water, it may be solidified with steam. As explained in detail above, the present invention is a method for obtaining aseptic packaged tofu through the steps (a) to (e), and instead of grinding soaked soybeans at room temperature in the conventionally known method for producing aseptic packaged tofu, By grinding at 50°C, there is less foaming when the go is heated, the protein insolubilization rate during soy milk sterilization is low, and tofu with a fine texture can be obtained. Examples are shown below. Example 1 Whole soybeans were washed and soaked in 4 times the amount of tap water for 16 hours, then drained, and 5 times the weight of the soybeans of warm water at 55°C was added to maintain the temperature at 50°C during grinding. At the same time, it was ground with a grinder (Model LM-S manufactured by Tokushu Kika Kogyo Co., Ltd.) to obtain Go. The resulting soybean was heated at 98°C for 1 minute by blowing steam into it, and filtered through a filter cloth to obtain soymilk with a protein concentration of 5.1%. This soymilk was homogenized using a high-pressure homogenizer (Model M manufactured by Manton-Gaulin) at a pressure of 400 kg/ ^cm2 , degassed, and then sterilized at 140℃ for 2 seconds using a plate sterilizer (Model P-20 manufactured by Alfa Arával). Heat sterilization was performed and the mixture was pooled in a sterilized storage tank while cooling. On the other hand, a 25% GDL aqueous solution was sterilized using a Millipore membrane filter (SW-47 manufactured by Millipore Limited), and a coagulant solution was added thereto at a volume of 1.0% per volume of soymilk, and this mixed solution was brought into a sterile atmosphere and pre-peroxidized. The soymilk is filled aseptically into a plastic container sterilized using hydrogen, sealed with a lid material also sterilized using hydrogen peroxide, and immersed in hot water at 90°C for 40 minutes to coagulate the soymilk, resulting in aseptically packaged tofu. Obtained. The obtained tofu had a fine texture, a good taste, and a good texture, and no change was observed even after storage at room temperature for 2 months. Example 2 Whole soybeans were washed and soaked in four times the amount of tap water at 20°C for 16 hours, then drained and ground at a temperature of 45°C.
Grinding machine (Model LM-S manufactured by Tokushu Kika Kogyo) while adding 5 times the weight of soybean warm water at 50℃ to maintain the temperature at ℃.
Grind it and get Kure. Steam is blown into the resulting soybean paste, which is cooled immediately after reaching a temperature of 100℃, and then filtered through a filter cloth to obtain a protein concentration of 5.1%.
of soy milk was obtained. This soymilk was homogenized using a high-pressure homogenizer (Model M manufactured by Manton-Gaulin) at a pressure of 200 kg/cm ² , degassed, and then sterilized using a plate sterilizer (Model P-20 manufactured by Alfa Arrabal) at 130°C for 5 seconds. The samples were heat sterilized and pooled in a sterilized storage tank while cooling. On the other hand, after sterilizing GDL and magnesium chloride by immersion in 75% ethyl alcohol, 10%
Diluted with sterile water to alcohol concentration. at this time
Concentration of GDL and magnesium chloride is 30% each
and 10%. Add and mix this coagulant solution in a volume of 1.0% based on the weight of soy milk, bring this mixed solution into a sterile atmosphere, fill it in a previously sterilized plastic container, seal it, and preheat it in hot water at 90℃ for 5 minutes. do this
The tofu was allowed to stay in a room filled with steam at 100°C for 20 minutes to heat and coagulate it, yielding aseptic packaged tofu. 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.

[Brief explanation of drawings]

Figure 1 shows the relationship between the grinding temperature and the insolubilization rate of protein in soymilk in Experimental Example 2, and Figures 2 to 4 show the relationship between the grinding temperature and the protein insolubilization rate in Experimental Example 2.
and 7 are cross-sectional micrographs of tofu obtained from Example 7.

Claims (1)

[Claims] 1. (a) A step of grinding soaked whole soybeans at 40 to 50°C to obtain go, (b) A step of heating the go to 80 to 100°C and then filtering it to obtain soymilk, (c) A process of obtaining soymilk by grinding the soybeans at a temperature of at least 130°C. (d) Aseptically adding and mixing a sterilized coagulant to the sterilized soymilk and aseptically filling and sealing it in a sterile container; (e) Sterilizing the sealed soymilk at a temperature of 70 to
A method for manufacturing aseptic packaged tofu that consists of heating to 100℃ and coagulating it.