JPH0421460B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing pressed tofu. More specifically, the present invention relates to an industrially advantageous method for producing pressed tofu having a dense structure and elasticity and a good texture. Pressed tofu is also called ``dried tofu'' or ``dried tofu'' in China, and is suitable for use as an ingredient in stir-fries due to its good shape retention.
In addition, as it is highly suitable for processing, it can be widely applied to various dishes, and its high nutritional value makes it suitable for health-conscious people, so the demand for it has been increasing in Japan as well. However, due to the low demand for conventional pressed tofu, the scale of production was small and it was almost handmade. Therefore, an industrially advantageous method for producing high-quality pressed tofu, that is, a method suitable for mass production, has not yet been established. In addition, conventional methods require an extremely long compression process, and a large amount of salt must be added to make the texture even harder, which narrows the range of applications for pressed tofu. was inviting. In view of the current situation, the inventors of the present invention have conducted extensive research to establish an industrially advantageous manufacturing method for high-quality pressed tofu. As a result, the inventors of the present invention have developed a method of dividing the curds to be subjected to compression treatment with appropriate water syneresis. The present inventors have discovered that this method is effective in the industrial production of high-quality pressed tofu, and have completed the present invention. Therefore, an object of the present invention is to provide an industrially advantageous method for producing pressed tofu. Another object of the present invention is to provide a new pressed tofu that has a dense structure, elasticity, and good texture. The above and other objects and features of the present invention will become more apparent from the following description. That is, in the present invention, a coagulant is added to an aqueous solution of soybean milk or isolated soybean protein having a solid content concentration of 8 to 20% by weight to form a curd, and the curd is subjected to a dividing treatment accompanied by syneresis to eliminate the occurrence of syneresis. The present invention relates to a method for producing pressed tofu, characterized in that the amount of moisture contained in the curd is 4 to 46% based on the total weight of the curd, and the curd is subjected to compression treatment to reduce the moisture content to 80% or less. Thus, by subjecting the curd to a separation treatment accompanied by water separation according to the method of the present invention, it becomes possible to advantageously produce the pressed tofu intended by the present invention on an industrial production scale. The method of the present invention will be explained in more detail below. In the method of the present invention, soy milk or an aqueous solution of isolated soy protein is used. Here, soy milk can be produced by a conventional method. For example, whole soybeans, dehulled soybeans, or defatted soybeans (not soaked in water) are used as raw materials.
→ Water immersion → Addition of water → Grinding (Kure) → Heat treatment → Separation →
(soy milk). In some cases, the heat treatment may be omitted at the "go" stage and the soy milk may be directly subjected to a separation process to produce soy milk. However, in the present invention, it is desirable to perform heat treatment such as boiling heat treatment at about 80 to 100°C for about 30 seconds to 10 minutes.
Incidentally, such heat treatment is a desirable step because it causes appropriate thermal denaturation of soybean protein, thereby increasing the water retention capacity of the finished tofu and further improving its mouthfeel. In addition, in the present invention, it is also possible to use so-called powdered soymilk obtained by pulverizing or granulating the soymilk obtained as described above by spray drying or the like. In this case, it is preferable to use this product after dispersing and dissolving it in water or hot water. On the other hand, the aqueous solution of isolated soy protein used in the present invention is obtained by adding a precipitant such as an acid to soy milk obtained by a conventional method to precipitate soy protein, and then dispersing and dissolving the precipitate in water again. . A curd is then formed by adding a coagulant to the thus obtained aqueous solution of soy milk or isolated soy protein. In the present invention, by setting the solid content concentration of soymilk (or isolated soybean protein aqueous solution) in the range of 8 to 20% based on the total weight of soymilk (or based on the total weight of isolated soybean protein aqueous solution), it is suitable for subsequent compression processing. In other words, it is possible to obtain soybean milk curd having a hardness that allows easy dehydration. More preferable results can be obtained by setting the solid content concentration to 10 to 18%. Furthermore, as the coagulant, any known coagulant for tofu can be used, such as glucono delta lactone (hereinafter referred to as GDL).
and divalent metal salts such as calcium sulfate. These can be used alone or in combination of two or more. The coagulant is used in a conventional manner. That is, the powder can be directly mixed with soybean milk or the like, or it can be dissolved in water in advance and added as a solution. The amount of coagulant added can be selected as appropriate; for example,
For GDL, 0.30-0.65% (weight ratio of soy milk)
It is preferable to use the curd within the range of 100 to 100%, in which case the curd will not have a sour taste and will have a hardness suitable for compression processing. Furthermore, 0.4-0.6%
Better results can be expected by using it within this range. Furthermore, when using calcium sulfate as a coagulant, the range is preferably 0.25 to 0.65% in order to obtain a card with a hardness suitable for compression treatment, and the more preferred range is 0.3 to 0.5%. The curd of the present invention can be obtained by adding a coagulant to the soybean milk or aqueous isolated soybean protein solution and allowing the mixture to stand for about 5 to 60 minutes after mixing. According to the present invention, the curd obtained as described above is then subjected to a separation treatment accompanied by water separation, and the water content thereof is 4 to 46% (based on the total weight of water contained in the curd).
is removed (hereinafter referred to as the amount of syneresis). In the present invention, the "amount of syneresis" is defined as the amount of syneresis that occurs when a card after separation is left on a 120-mesh stainless steel wire mesh for 15 minutes. This separation process accompanied by water syneresis makes it easier for the moisture in the card to seep out, which increases the dewatering efficiency during the compression process, and enables an extremely effective short-term compression process, resulting in dense It becomes possible to obtain pressed tofu with good texture and texture and appropriate elasticity. If this dividing treatment is not performed, or if the amount of water released from the card by dividing treatment is less than 4%, it will be difficult for the moisture inside the card to seep out during compression treatment, and therefore a long-term compression treatment will be necessary. As a result, productivity also decreases. In addition, if the compression process is performed under high pressure without dividing to shorten the compression process time, the tofu structure will be greatly destroyed, making it difficult to obtain pressed tofu with a dense structure, which is the objective of the present invention. Can not. On the other hand, if the amount of syneresis exceeds 46%, pressed tofu with good texture cannot be obtained, and the result is pressed tofu that lacks the compactness and elasticity that are the lifeblood of pressed tofu, and has a crumbly texture with poor texture. Therefore, in order to obtain the pressed tofu that is the object of the present invention, the amount of syneresis generated during the dividing process is critical.
It is necessary that it be within the above range. Furthermore, when the amount of syneresis is set to 9 to 32%, it becomes possible to obtain pressed tofu that is even more excellent in the denseness and elasticity of the tofu structure. The dividing process in the present invention may be any process that can physically divide the tofu curd tissue. Specific aspects are as follows. (b) Cutting process: Cut the card with a cutter, etc.
Note that the cut shape may be arbitrary, such as a cylindrical shape or an irregular shape. (b) Crushing process: Crush the cards using an agitator or the like. (c) Drilling process: Use small diameter metal rods, etc. to drill holes at appropriate intervals. (d) Engraving process: Engraving an appropriate number of line grooves on the card using a cutter, etc. Note that the above-mentioned dividing process may be performed at any stage, for example, while the card is maintained in its forming container, after being transferred to another container, or after the card is further filled into a compression container. . In addition, among the above-mentioned dividing processes, the cutting process (a), the punching process (c), or the engraving process (d) maintain the overall shape of the card without significantly destroying the card structure. The above three types of pressed tofu can be used to efficiently carry out the compression process so that the moisture contained in the curd can easily ooze out while the curd is still standing, and to obtain pressed tofu that is elastic, denser, and has a good texture. It is preferable to use the following treatment method. In the present invention, the card after the cutting process is filled into a compression container (if the cutting process is performed in the compression container, the card is left as it is), and the card is compressed to reduce the water content to 80% or less. The compression container used in this process may have any shape or capacity. However, it is preferable that an appropriate number of holes be provided on the side or bottom surface of the container in order to facilitate dehydration of moisture contained in the curd to the outside of the container during compression.
In addition, it is preferable to use a compression device such as a hydraulic press for this compression treatment, and to gradually increase the pressure from low pressure to high pressure, thereby suppressing the destruction of the card structure. It is possible to obtain pressed tofu with a dense and elastic texture. To give an example of the operating conditions, approximately 0.04 to 0.6 kg/
Compression operation is started at an initial pressure of 0.2 to 0.4 Kg/cm ² , preferably 0.80 to 3.2 kg/cm ² , and the pressure is gradually increased to approximately 0.80 to 3.2 kg/cm 2 .
It is desirable to complete the operation at a final pressure of Kg/cm ² , preferably 1.2-2.0 Kg/cm ² . In addition, the compressive load per unit area of the surface part of the compressed object (tofu curd after dividing treatment) of the present invention is shown as a unit (the same applies hereinafter). In the present invention, since the card to be compressed is divided in advance, the dehydration efficiency of the card is high. Therefore, it is possible to complete the compression process in an extremely short time of about 10 to 90 minutes. The compression process also reduces the moisture content of the curd.
By setting it to 80% or less, it becomes possible to obtain pressed tofu having a dense structure and appropriate hardness. The thus obtained pressed tofu of the present invention can be filled into a heat-resistant container made of synthetic resin or the like, sealed, and then subjected to heat treatment such as hot water sterilization or high-temperature and high-pressure treatment using a retort. Such heat treatment not only imparts the desired preservability to the pressed tofu, but also binds together the curd structure that was once cut in the previous cutting process to create an even more dense structure, and further improves elasticity. Therefore, it is advantageous. The heat treatment is preferably carried out at a temperature of about 80 to 135°C for about 5 to 60 minutes, and particularly the heat treatment is carried out at a temperature of about 90 to 105°C.
It is even more preferable to carry out the cooking for 10 to 20 minutes at a temperature of 100 to 200, because the texture is more markedly improved. Hereinafter, the present invention will be explained in more detail with reference to Examples and Control Examples. Example 1 Whole soybeans are soaked in water, water is added to the soybean, ground, and the resulting soybean is centrifuged to remove okara.
Soy milk with a solid content of 11.2% was obtained. After the soybean milk thus obtained was boiled for 1 to 2 minutes, 0.6% GDL (weight ratio to soybean milk) was added as a coagulant, mixed, and left to stand for an additional 15 minutes to form a curd. Next, the card is placed in a compression container with an appropriate number of holes on the side, lined with a drying cloth, and filled, and then the card is vertically inserted by inserting a thin stainless steel plate vertically from above the card. It was cut into 10mm square pieces in the shape of a scythe and divided into pieces. The amount of syneresis generated after the same separation treatment was 22%. The amount of syneresis was measured as the amount of syneresis when the card after the separation treatment was left on a 120-mesh stainless steel wire mesh for 15 minutes. Further, the following examples were also based on the same measurement method. Next, this is 0.20Kg/0.20Kg/
Compression was performed while gradually increasing the pressure from cm ² to 1.2 Kg/cm ² (compression time: 39 minutes) to obtain pressed tofu (sample A) according to the present invention with a moisture content of 72.7%. Example 2 Cards obtained by the same method as Example 1 were crushed with an agitator and subjected to fragmentation treatment (the amount of syneresis generated after fragmentation treatment was 35%), and then filled into a compression container in the same manner as Example 1. Then, it was compressed using a hydraulic press machine while gradually increasing the pressure from 0.20Kg/cm ² to 1.2Kg/cm ² (compression time: 25 minutes) to obtain a product according to the present invention with a moisture content of 71.1%. Pressed tofu (sample B) was obtained. Comparative Example 1 A card obtained in the same manner as in Example 1 was filled into a compression container in the same manner as in Example 1 without being divided, and then compressed to 0.20 kg using a hydraulic press. The mixture was compressed while gradually increasing the pressure from /cm ² to 1.2 Kg/cm ² to obtain a control pressed tofu (sample C) with a moisture content of 75.1% (compression time: 6 hours). Comparative Example 2 Similar to Example 2, the card was crushed with an agitator and subjected to fragmentation treatment (however, the amount of syneresis generated after the fragmentation treatment was 3.5%), and then filled into a compression container in the same manner as Example 1. , and then compressed using a hydraulic press while gradually increasing the pressure from 0.20Kg/cm ² to 1.2Kg/cm ² (compression time: 3.5 hours) to determine the water content.
A control product pressed tofu (sample D) with a yield of 74.3% was obtained. Control Example 3 In the same manner as in Example 2, the card was crushed and divided using an agitator. The card state after the same cutting process is close to that of paste, and the amount of syneresis generated is
It was 44%. Next, this was filled into a compression container in the same manner as in Example 1, and then compressed to 0.20 kg/kg using a hydraulic press.
Compression was performed while gradually increasing the pressure from cm ² to 1.2 Kg/cm ² (compression time: 17 minutes) to obtain a control pressed tofu (sample E) with a water content of 70.9%. Comparative Example 4 In the same manner as in Example 1, the card was subjected to a dividing process and then hydraulically pressurized to 0.2Kg/cm ²
The mixture was compressed while gradually increasing the pressure from 1 to 0.8 Kg/cm ² (compression time: 1.9 minutes) to obtain a control pressed tofu (sample F) with a water content of 82.2%. The samples obtained above were compared in terms of density (hardness) and elasticity through a taste test. The results are shown in Table 1.

【table】

[Table] As is clear from the above results, control samples C and D are not subjected to the separation treatment of the present invention or correspond to the lower limit of syneresis of the present invention.
It takes a long time to compress, making it unsuitable for industrial production. Furthermore, the control sample E, which exceeds the upper limit of the specific syneresis amount of the present invention, and the control sample F, whose moisture content after compression deviates from the present invention, both have the compactness and elasticity that can be said to be the lifeblood of pressed tofu. does not have On the other hand, samples A and B according to the present invention can both be compressed efficiently and are satisfactory as pressed tofu in terms of quality.

Claims (1)

[Claims] 1. A coagulant is added to soybean milk or an aqueous solution of isolated soybean protein with a solid content concentration of 8 to 20% by weight to form a curd, and the curd is subjected to a separation process accompanied by syneresis, and the amount of syneresis generated is calculated from the amount of syneresis produced by the curd. A method for producing pressed tofu, characterized in that the water content is 4 to 46% based on the total weight of the tofu, and the pressed tofu is subjected to compression treatment to reduce the water content to 80% or less.