JP2020010627A - Method for producing frozen raw bean curd skin - Google Patents

Abstract

To provide a method for producing a frozen raw bean curd skin capable of inhibiting the raw bean curd skin from being reduced in palate feeling and flavor and discolored due to freezing and thawing.SOLUTION: The method for producing a frozen raw bean curd skin according to the present invention includes a soybean milk preparation step of adding 31 to 50 wt.% of saccharides to raw material soybean milk to prepare soybean milk for preservation, a freezing preparation step of storing raw bean curd skin produced by using the raw material soybean milk to which no saccharides are added and the soybean milk for preservation in a freezing container, a freezing step of freezing the raw bean curd skin and the soybean milk for preservation which are stored in the freezing container in a temperature zone of -20 to -80°C, and a freezing storage step of storing the raw bean curd skin and the soybean milk for preservation in the freezing container in a frozen state, in a temperature zone of -18 to -80°C.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a technique for freezing raw yuba, such as raised yuba and kumiage yuba.

  Yuba, one of the processed foods of soybeans, is produced by heating a soymilk and scooping up a film formed on the liquid surface with a thin rod-shaped device. Yuba includes raw yuba and dried yuba. Raw yuba refers to the film itself scooped up from the liquid surface of soy milk, and dried yuba refers to the dried film scooped up. Raw yuba is cooked as it is, and dried yuba is cooked after returning with water and softening.

  In addition, raw yuba is divided into those that are scooped up after the film is completely formed on the liquid surface of soy milk, and those that are gathered and scooped up before the film is completely formed on the liquid surface of soy milk. Is called "Kaiage Yuba", and the latter is called "Kumiage Yuba" (also called "Tsumami Yuba"). Unless otherwise specified, in the present specification, both the raised Yuba and the Kumiage Yuba are collectively referred to as “raw Yuba”.

  Raw yuba has better texture and flavor than dried yuba, and is used as an ingredient in various dishes. In addition, raw yuba can be eaten with a seasoning such as soy sauce as it is without heating. However, unlike dried yuba, raw yuba has a drawback that it is easily rotted and cannot be stored for a long time.

  Therefore, there has been provided a product in which the storage period is extended by freezing raw yuba, but raw yuba thawed after frozen storage is inferior in texture and flavor as compared with raw yuba before freezing. This is because the protein contained in the raw yuba is denatured and aggregated by freezing the raw yuba, and once aggregated, the protein does not return to the original state. Therefore, when the frozen raw yuba is thawed, the raw yuba becomes hard due to the aggregated protein, and the texture and flavor are reduced.

JP 2001-057860 A

  As a solution to the above-mentioned problem, Patent Document 1 discloses that the texture of frozen soybean milk is added by adding a predetermined amount of saccharide to soymilk as a raw material of raw yuba or soymilk for immersing raw yuba. And a method for producing frozen raw yuba with a suppressed reduction in flavor. However, raw yuba frozen and stored by the method described in Patent Literature 1 may have a brown discoloration during frozen storage or thawing, which has a problem in appearance.

  The problem to be solved by the present invention is to provide a technique for producing frozen raw yuba that can suppress the deterioration and discoloration of the texture and flavor of the raw yuba due to frozen storage and thawing.

A method for producing a frozen raw yuba according to the present invention made to solve the above-mentioned problem,
a) a soymilk preparation step of adding 31 to 50% by weight of saccharide to raw soymilk to prepare soymilk for storage;
b) raw yuba manufactured using raw soymilk to which no sugar is added, and a freezing preparation step of preparing a freezing container containing the storage soymilk,
c) a freezing step of cooling and freezing the raw yuba and the stored soymilk contained in the freezing container to a temperature range included in a range of -20 ° C to -80 ° C;
d) storing the raw yuba and the soymilk for storage in the frozen container in a frozen state in a temperature range included in the range of −18 ° C. to −80 ° C.

  In the present invention, various types of sugars are included in the soymilk for preservation, but those having as little sweetness as possible are preferable. This is because the purpose of using the soymilk for preservation containing a saccharide in the present invention is to alleviate the damage to the raw yuba that is caused by freezing or frozen storage by the saccharide. By using a saccharide having a low sweetness, the effect of the saccharide on the taste of the raw yuba can be reduced when the storage soymilk containing the saccharide is frozen together with the raw yuba and stored frozen. In addition, monosaccharides and disaccharides are preferable to polysaccharides in that they have excellent solubility in raw material soymilk, and not only one kind but also a plurality of kinds of sugars can be used. For example, trehalose, lactose, and maltose are known as sugars having low sweetness. These are all disaccharides. In addition, in this invention, although the saccharide was added to the raw material soymilk and it was set as the soymilk for preservation, even if the thing which added the amino acid (glycine) to the raw material soymilk was used as the soymilk for preservation, the same effect as the present invention is obtained Has been confirmed.

  In the present invention, the method for producing the raw soymilk used in the soymilk preparation step and the raw soymilk used in the production of raw yuba is the same as the general method for producing soymilk. That is, soybeans immersed in water are further ground by adding water to obtain raw gou. After heating the raw gou to obtain boiled gou, the soymilk (raw soymilk) is squeezed out. can get.

In the soymilk preparation step, a raw material obtained by adding 31 to 50% by weight of saccharide to the above raw material soymilk is used, and for the production of raw yuba, the above raw material soymilk is used as it is (that is, without adding saccharides). .
In this case, the raw soymilk used for the storage soymilk preferably has a higher Brix value than the raw soymilk used for the production of raw yuba, and in particular, the storage soymilk has a Brix value of 7 to 9 degrees. It is preferable to use raw soymilk having a Brix value of 4 to 6 degrees for the production of raw yuba. The Brix value in soy milk refers to the concentration of soluble solids, and a higher value means that more soluble solids are included.

  Raw yuba is obtained by heating raw soymilk placed in a kettle to 75 ° C. to 95 ° C., whereby proteins are thermally coagulated, and the film formed on the liquid surface of the raw soymilk is scooped up with an elongated rod. When the film is completely formed on the liquid surface of the raw material soy milk, it is pulled up when it is picked up, and when it is picked up before the film is completely formed, it is picked up. Since the more soluble solids contained in the raw soymilk used in the production of raw yuba, the faster it solidifies, the higher the brix value of the raw soymilk, the higher the brix value (for example, 5-6 degrees) when producing the raised yuba. When producing, the Brix value of the raw material soymilk should be slightly lower (for example, 4 to 5 degrees).

  The film picked up from the kettle is stored in a container. This container may be the above-mentioned container for freezing, or may be a container other than the container for freezing. The raw material soymilk before becoming a film adheres to the film housed in the container. Since the temperature of the film and the raw soymilk is high for a while after being stored in the container, the thermal coagulation of the protein in the raw soymilk proceeds. Then, the raw coagulation is completed by the completion of the thermal coagulation of the protein due to a decrease in temperature or the like. When the above operation is performed in a container different from the freezing container, the raw yuba formed in the other container is transferred to the freezing container. Then, the soymilk for preservation is added to the freezing container containing the raw yuba. Thus, a container for freezing containing raw yuba and soymilk for storage is prepared.

  In addition, soymilk for preservation may be added while heat coagulation of the protein is progressing in the container. Thereby, the progress of the thermal coagulation of the protein can be suppressed or stopped halfway. Usually, if the storage soymilk is at room temperature (around 15 ° C.), protein coagulation can be stopped. Therefore, raw yuba with different softness and viscosity can be obtained by changing the timing and amount of addition of soymilk for preservation, and the temperature of soymilk for preservation to be added. The soybean milk for preservation added to the container as described above may partially coagulate, but most of the soymilk remains in the container in a liquid state. When the above operation is performed in a container different from the freezing container, the raw yuba and the soymilk for storage formed in the other container are transferred to the freezing container. Thus, a container for freezing containing raw yuba and soymilk for storage is prepared.

  The raw yuba and the soymilk for storage in the freezing container obtained as described above are cooled and frozen to a temperature range included in the range of -20C to -80C. In order to prevent evaporation and contamination of the soymilk for storage during freezing and during frozen storage described below, preferably the freezing container is closed with a lid or the like, more preferably sealed, and even more preferably sealed after degassing. You. The raw yuba in the freezing container has a surface covered with soymilk for preservation, so that the raw yuba does not dry during freezing. Further, since the soymilk for preservation contains a high concentration of saccharides of 31 to 50% by weight, not only the denaturation and coagulation of the protein in the soymilk for preservation at the time of freezing but also the denaturation of the protein in the raw yuba are suppressed. be able to. Furthermore, since the denaturation and coagulation of the protein in the soymilk for preservation are suppressed, discoloration of the raw yuba during thawing can also be suppressed.

  The raw yuba and the soymilk for storage in the freezing container frozen by the above method are stored in a temperature range included in the range of -18C to -80C. In this case, the frozen food may be stored frozen at -18 ° C to -30 ° C, which is a general storage temperature range of ordinary frozen foods. However, denaturation and coagulation of proteins in raw yuba and soymilk for storage during frozen storage. From the viewpoint of suppressing the temperature, it is preferable to store frozen at a lower temperature range of −30 ° C. to −80 ° C.

  The method of thawing the raw yuba and the soy milk for storage in the container for freezing after freezing and preservation is preferably thawing with running water, which is generally recommended as a method for thawing a frozen product of fresh food. If the temperature of the flowing water is in the range of 0 ° C. to 20 ° C., the taste, texture and color of the raw yuba after thawing are almost the same as those of freshly prepared raw yuba. Moreover, in the present invention, raw soymilk used for raw yuba does not contain saccharides, so that the original taste of raw yuba can be maintained.

In the above method, the freezing container is a hermetically sealable container,
In the freezing step, it is preferable that the freezing container containing the raw yuba and the soymilk for storage is hermetically sealed and immersed in liquid alcohol cooled to a temperature in the range of −20 ° C. to −80 ° C. By adopting the above method, the raw yuba and the soymilk for storage in the freezing container can be cooled and frozen to a temperature included in the range of −20 ° C. to −80 ° C. in a short time. As a result, the raw yuba and the soymilk for preservation in the freezing container can rapidly pass through the maximum ice crystal formation temperature zone (-1 ° C to -5 ° C). Crystal growth can be suppressed, and the damage to raw yuba during freezing can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, raw yuba can be preserve | saved frozen, without reducing texture and flavor. Moreover, since the freshly stored raw yuba does not significantly change its color when it is thawed, it is possible to obtain a frozen raw yuba equivalent to freshly prepared raw yuba not only in texture and flavor but also in appearance. Can be. In particular, the pumped-up yuba manufactured by scooping up the film before the film is completely formed contains a large amount of soy milk in its manufacturing method, so that the texture and flavor of frozen food are significantly lower than that of the pulled-up yuba. According to the present invention, the texture, flavor, and color can be maintained even when the stored hot water is frozen and stored.

The figure which shows the apparatus for liquid-freezing raw yuba. The photograph which shows the external appearance of Kumiage Yuba whose evaluation of texture is "x or △", "○", and "◎". The graph which shows the temperature change inside raw yuba when the raw yuba is liquid-frozen. FIG. 4 is a photograph of a Kyuage yuba prepared using soymilk for preservation containing 42% by weight of trehalose, which is gas-frozen at −40 ° C., stored at −40 ° C. for 2 weeks, and then slowly thawed. The photograph when the pumped-up yuba prepared using the soymilk for preservation containing 42 weight% of trehalose was gas-frozen at -40 degreeC, stored at -40 degreeC for 2 weeks, and thawed with running water. The right-hand side is a photograph of the water when the pumped-up yuba prepared using trehalose-free soymilk for storage is gas-frozen at −40 ° C., stored at −40 ° C. for 2 weeks, and then thawed with running water. A photograph is shown when the pumped-up yuba prepared using storage-free soymilk containing no liquid is liquid-frozen at −40 ° C., stored at −40 ° C. for 2 weeks, and then thawed with running water. The left-hand side is a photograph taken out of the freezer after gas-freezing Kumiage Yuba prepared using soymilk for preservation containing 42% by weight of trehalose at −40 ° C., storing at −40 ° C. for 2 weeks, The right-hand side shows a photograph in which the pumped-up yuba prepared using soymilk for storage containing 42% by weight of trehalose is liquid-frozen at −40 ° C., stored at −40 ° C. for 2 weeks, and then taken out of the freezer. A photograph of Kumiage Yuba prepared using trehalose-free soymilk for storage, which was gas-frozen at -80 ° C, degassed, stored at -20 ° C for 2 weeks, and then thawed with running water. Kumage yuba prepared using trehalose-free soymilk for storage was put in a plastic tube, gas-frozen at -80 ° C, frozen and stored at -80 ° C or -20 ° C for 2 weeks, and then thawed with running water. Pictures of things.

Hereinafter, the method for producing frozen raw yuba according to the present invention will be specifically described.
The present inventor, in the development of the production method according to the present invention, by changing the sugar concentration in the soymilk for storage, the freezing temperature and the freezing method of raw soybean milk and the soymilk for storage, and the frozen storage temperature, to produce frozen raw yuba, and its color A test was conducted to examine the taste, texture, and color of the raw yuba after thawing. Hereinafter, this test will be described.

(1) Preparation of soy milk Water is added to soybeans immersed in water and ground to obtain raw gou. Subsequently, the raw go was heated, and the resulting boiled go was squeezed to obtain soy milk. At this time, the amount of water added when grinding soybeans and the amount of water added to boiled soybeans were adjusted so that the Brix value of the obtained soy milk was 4 to 6 degrees or 7 to 9 degrees. In addition, according to a general method for producing soymilk, parameters of a grinder (grinding rotation speed, grinding time, etc.), temperature and time for heating raw go, and the like were appropriately adjusted. Hereinafter, soymilk having a Brix value of 4 to 6 degrees is referred to as raw soymilk for raw yuba, and soymilk having a Brix value of 7 to 9 degrees is referred to as raw soymilk for storage soymilk.
Next, trehalose is added at a ratio of 31% by weight, 42% by weight, and 62% by weight to the raw material soymilk for storage soymilk, and each is cooled to about 15 ° C. As a comparative example, soymilk for storage containing no trehalose was also prepared and cooled to about 15 ° C.

(2) Production of Kumiage Yuba Raw material soymilk having a Brix value of 4 to 6 is put in a kettle, and the kettle is heated with steam to maintain the temperature of the raw material soymilk at about 80 ° C. Then, when a thin film starts to form on the liquid surface of the raw soymilk, the films are gathered together, scooped up with chopsticks, and put into a yuba preparation container. This yuba preparation container is a container different from the freezing container. If the scooped film exceeds a predetermined thickness, the soft texture of the finished raw yuba is impaired, so be careful of the timing of scooping the film.

  When the film is picked up with chopsticks, a large amount of raw soymilk adheres to the film. Therefore, not only the film but also the raw soybean milk is contained in the yuba preparation container. Since the temperature of the film and the raw material soymilk is high for a while after being placed in the yuba preparation container, the solidification of the protein contained in the film and the raw material soymilk proceeds. Therefore, at an appropriate timing, the soymilk for storage cooled to about 15 ° C. is added to the yuba preparation container to stop coagulation of the protein. Thereby, a pumped-up yuba whose viscosity and softness are substantially constant can be obtained.

  In this test, when making about 200 g of raw yuba (that is, when putting a total of about 200 g of the film and the raw soymilk in the yuba preparation container), 10 to 20 mL of soymilk for storage was added. Not done. The amount of added soymilk for preservation may be appropriately adjusted according to the type of soybean, the temperature during operation, and the like. The pumped-up yuba and the soymilk for preservation in the yuba preparation container obtained as described above were divided into equal amounts in a freezing container, and the air in the freezing container was evacuated with a vacuum packaging machine, followed by sealing. Here, a bag made of a sheet material in which a nylon film and a lowdenpoly (low-density polyethylene (LDPE)) film were adhered was used as a container for freezing.

(3) Freezing treatment of Kumiage yuba (3-1) Freezing treatment method A sealed freezing container containing Kumiage yuba and soymilk for preservation is cooled in running water. Then, when the temperature of the pumped water inside the freezing container reached 10 to 20 ° C., the freezing container was taken out of running water and frozen by the following three methods.
(a) Gas freezing: A freezing container is housed in a general freezer (set temperature: -20 ° C, -40 ° C, -60 ° C, -80 ° C).
(b) 3D quick freezing: A freezing container is housed in a freezer (set temperature: -40 ° C) where cold air is blown into the refrigerator from three directions.
(c) Liquid freezing: As shown in FIG. 1, an alcohol 1A is put in a rectangular container 1, and a freezing container (bag) 2 is immersed in the alcohol 1A (set temperature:- 20 ℃, -40 ℃, -60 ℃, -80 ℃) When the freezing temperature was −80 ° C., the alcohol having an alcohol content of 75 degrees was placed in the rectangular container 1, and otherwise, the alcohol at 68.9 degrees was placed in the rectangular container 1.

(3-2) Type of freezer used for freezing treatment The freezers shown in the following table were used.

(3-3) Freezing time
In any of (a) to (c), the internal temperature of the raw yuba in the freezing container was measured with a temperature sensor, and the temperature reached −20 ° C., −40 ° C., −60 ° C., −80 ° C. Was confirmed and the freezing container was taken out of the freezer. The freezing times of (a) to (c) were as follows.
(a) 8 hours
(b) 1 hour and 30 minutes
(c) 20 minutes

(4) Freezing and preservation In a state where the frozen pumped-up yuba and the soymilk for preservation are kept in a freezing container in a freezer set at a temperature of −20 ° C., −35 ° C., and −80 ° C. for 2 weeks, And stored for one month. Here, the pumped-up yuba after frozen storage is also referred to as “frozen pumped-up yuba”.

(5) Thawing At the temperature and period shown in (4), the pumped-up yuba and the soymilk for preservation stored in the freezer were thawed under the following conditions while being kept in a freezing container.
(a) Thawing in running water (0 to 20 ° C) for about 1 hour (flowing water thawing)
(b) Thaw in a low-temperature (0 ° C to 10 ° C) environment for about 8 hours (slow thawing)

(6) Results Eight panelists evaluated the taste and texture of Kumiage Yuba after thawing. The taste and texture were evaluated as follows.
◎: Equivalent to freshly made Kumiage Yuba ○: Slightly inferior to freshly made Kumiage Yuba, but commercially viable △: Inferior to freshly made Kumiage Yuba and cannot be commercialized ×: Than freshly made Kumiage Yuba In addition, FIG. 2 is an external appearance photograph of Kumiage Yuba with a texture evaluation of × or Δ, 、, ◎.

In addition, the color of the pumped-up yuba immediately after being taken out of the freezer for thawing was evaluated as follows.
◎: White color equivalent to freshly made Kumiage Yuba products ○: Light brown to white △: Brown to Light brown ×: Dark brown to Light brown Note that the freezer is assumed to be in the condition of frozen Kumiage Yuba when sold at stores It was evaluated with the color immediately after it was taken out from the product, but regardless of the evaluation at this time, any of "◎" to "x", by thawing, the color of Kumiage Yuba is almost the same as the freshly made Kumiage Yuba product Became white.

  As a result, those subjected to slow thawing were evaluated as 味 or × for taste and texture, regardless of the concentration of trehalose contained in the soymilk for storage, the freezing method, the temperature of the frozen storage, and the storage period. This means that the damage to the pumped-up yuba by slow thawing is large. On the other hand, those subjected to thawing in running water had different evaluations of taste and texture depending on the concentration of trehalose contained in the soymilk for storage, the freezing method, and the temperature of the frozen storage. Table 2 shows the evaluation results of the pumped-up yuba with the freezing storage period set to 2 weeks. In Table 2, the hatched columns indicate that no test was performed. The evaluation results of the pumped-up yuba with a frozen storage period of one month were almost the same as the evaluation results of the pumped-up yuba with a frozen storage period of 2 weeks, and therefore the description is omitted here.

(6) Discussion (6-1) Frozen pumped-up yuba of comparative example (concentration of saccharides is 0%) in which trehalose is not added to soymilk for storage, freezes at -80 ° C, gas-freezes, and reduces the frozen storage temperature to- When the temperature is 80 ° C., the freezing temperature is −60 ° C., and the liquid is frozen. When the frozen storage temperature is −60 ° C., the evaluation of the color, taste, and texture is “」 ”or“ 」”. there were.

  On the other hand, when the freezing temperature was −80 ° C. or −60 ° C., and the frozen storage temperature was −20 ° C., the color evaluation was “」 ”or“ ○ ”in both gas freezing and liquid freezing. , The evaluation of taste and texture was "x", which was very inferior to freshly made Kumiage Yuba.

  When the freezing temperature was -40 ° C and the 3D quick-freezing was performed, and the frozen storage temperature was -35 ° C, the evaluation of the texture was “x”, which was very inferior to freshly made Kyuage Yuba. And the evaluation of taste was “△”, which was slightly inferior to freshly made Kumiage Yuba. When the liquid was frozen at a freezing temperature of −40 ° C., and the frozen storage temperature was −35 ° C., the evaluation of the texture was “×”, which was very inferior to freshly made Kyuage Yuba, The evaluation of color was “◎”, and the evaluation of taste was “△”.

  On the other hand, when the freezing temperature is -40 ° C. and the 3D quick-freezing is performed and the frozen storage temperature is -20 ° C., the color evaluation is “△”, which is slightly inferior to freshly-prepared yuba. The evaluation of both the texture and the freshness was “x”, which was very inferior to the freshly made Kumiage Yuba. When the liquid was frozen at a freezing temperature of −40 ° C. and the frozen storage temperature was −20 ° C., the evaluation of color was “「 ”, but the evaluation of taste and texture was“ × ”. It was very inferior to freshly made yuba.

  When the liquid was frozen at a freezing temperature of −20 ° C. and the frozen storage temperature was −20 ° C., the evaluation of the color when thawed was “○”, which was almost the same as freshly made Kyuage Yuba, The evaluation of taste and texture was “x”, which was very poor. Further, when the freezing temperature was set to -20 ° C and the gas was frozen and the frozen storage temperature was set to -20 ° C, all evaluations of color, taste and texture were “x”.

  From the above results, except when the gas is frozen at −20 ° C., even if trehalose is not contained in the soymilk for preservation, the color of the pumped-up yuba is not significantly deteriorated by freezing and frozen storage. It was found that the taste and texture deteriorated depending on the freezing method and the freezing storage temperature. Specifically, even if trehalose is not contained in the soymilk for storage, the freezing temperature is set to a temperature of -40 ° C or lower, and the frozen storage temperature is set to a temperature lower than -20 ° C, whereby the deterioration of color and taste is reduced. It is possible to avoid all deterioration of color, taste, and texture by setting the freezing temperature lower than −40 ° C. and the frozen storage temperature lower than −35 ° C. It turned out to be possible.

(6-2) Frozen Kumage Yuba using storage soybean milk containing 31% by weight and 42% by weight of trehalose Regardless of the method and temperature of freezing and freezing storage, the evaluation of taste and texture is "O" or It was "◎", which was equivalent to or slightly inferior to freshly made Kumiage Yuba.
When the liquid was frozen, the color was evaluated as “「 ”or“ ◎ ”regardless of the freezing temperature and the freezing storage temperature. On the other hand, in the case of gas freezing, when the freezing temperature was −80 ° C. and the frozen storage temperature was −20 ° C., the evaluation of the color was “○”, but the evaluation of other colors was “Δ” or “ × ”, which was inferior to freshly made Kyuage Yuba. From this, it was found that by using soymilk for storage containing 31% by weight and 42% by weight of trehalose, deterioration of color, taste and texture due to freezing and frozen storage can be suppressed. In particular, even when stored frozen at -20 ° C, the color, taste and texture hardly deteriorated. Therefore, the color, taste and texture obtained by freezing storage in a general home refrigerator (around -20 ° C) It seems that the degradation of can be kept small.

(6-3) Frozen Kumiage Yuba using storage soymilk containing 62% by weight of trehalose The evaluation of the texture is “◎” or “「 ”regardless of the method and the temperature when frozen and stored frozen. It was the same as or slightly inferior to freshly made Kumiage Yuba, but the evaluation of taste was "△", indicating that it was worse than freshly made Kumiage Yuba. Deterioration of taste was considered to be largely affected by trehalose contained in large amounts in soymilk for preservation. On the other hand, the evaluation of the color was almost the same as that in the case of using soymilk for storage containing 31% by weight and 42% by weight of trehalose.

FIG. 3 is a result of examining a temperature change of the pumped water when the liquid is frozen. Here, alcohol 2A (alcohol number: 68.9 ° C.) having a temperature of −35 ° C. is placed in a plastic rectangular container 2 having a size of 170 × 110 × 30 (mm ³ ), and 350 g of hot water is stored therein. The refrigeration container (sealed bag) 1 was immersed, and the rectangular container 2 was accommodated in the freezer.
As shown in FIG. 3, the temperature of the pumped-up yuba, which was about 10 ° C. when stored in the freezer (at the time of charging), gradually decreased, and from about 9 minutes to 17 minutes and 30 seconds, 8 minutes 30 minutes. It passed the maximum ice crystal formation zone in seconds. Thereafter, the temperature rapidly decreased until the product was taken out of the freezer 23 minutes after the introduction, and the temperature of the pumped-up yuba at the time of taking out was about -22.5 ° C.

As described above, in liquid freezing, the temperature of Kyuage Yuba drops rapidly, and in particular, since the passage time of the maximum ice crystal formation zone is short, the particle size of the ice crystals generated in the tissue of Kumiage Yuba becomes small, and freezing occurs. Occasionally, the damage received by the pump is reduced.
Further, when the particle size of the ice crystals purified in the tissue of Kumiage Yuba is small, the amount of the soymilk for preservation covering the surface crystal per volume of the ice crystals increases, and further, the amount of saccharides contained in the soymilk for preservation is increased. Higher amounts result in more sugar covering the ice crystals (ie, the ice crystals are protected by sugars).
From the above, it is considered that the best effect (suppression of deterioration in color, taste, and texture by freezing and frozen storage) is obtained when liquid-frozen Kumage-Yuba using preservative soymilk containing saccharides.

[Example]
Based on the above results, the results of manufacturing frozen pumped yuba will be described with reference to FIGS.
FIG. 4 is a photograph of Kumiage Yuba prepared using soymilk for storage containing 42% by weight of trehalose, which was gas-frozen at −40 ° C., stored frozen at −40 ° C. for 2 weeks, and then slowly thawed. FIG. 5 is a photograph of Kumiage Yuba prepared using soymilk for storage containing 42% by weight of trehalose, which was gas-frozen at −40 ° C., stored frozen at −40 ° C. for 2 weeks, and then thawed with running water. is there.
As shown in FIG. 4, the frozen pumped yuba became hard due to denaturation of the protein during thawing. The taste after thawing was also bad. On the other hand, the frozen Kumiage Yuba shown in FIG. 5 was equivalent in color, taste, and texture to fresh Kumiage Yuba.

  The left side of FIG. 6 is a photograph taken from the freezer after gas-frozen at −40 ° C., freeze-preserved at −40 ° C. for 2 weeks, and gas-frozen Kyuage yuba prepared using soymilk for preservation containing no trehalose. The right-hand side is a photograph when the pumped-up yuba prepared using trehalose-free soymilk for preservation is liquid-frozen at −40 ° C., frozen and stored at −40 ° C. for 2 weeks, and then taken out of the freezer.

  The left side of FIG. 7 shows the case where Kumiage Yuba prepared using storage soymilk containing 42% by weight of trehalose was gas-frozen at −40 ° C., stored frozen at −40 ° C. for 2 weeks, and then taken out of the freezer. A photograph is shown on the right, when the Kumiage Yuba prepared using soymilk for preservation containing 42% by weight of trehalose is liquid-frozen at -40 ° C, stored frozen at -40 ° C for 2 weeks, and then taken out from the freezer. It is a photograph of.

  As shown in FIGS. 6 and 7, when trehalose is not contained in the soymilk for preservation, in any case where trehalose is contained, the liquid frozen at −40 ° C. is better than the gas frozen at −40 ° C. Also, it was found that the color of the pumped-up yuba and the soymilk for preservation after frozen storage was white, and the discoloration was suppressed by liquid freezing.

  Also, as can be seen from the comparison of FIGS. 6 and 7, when frozen by the same method, regardless of whether the soymilk for preservation contains 42% by weight of trehalose or not, the color of the frozen pumped-up yuba after the frozen storage. There was no big difference. That is, when frozen in liquid, regardless of whether or not 42% by weight of trehalose is contained in the soymilk for storage, the color of the frozen pumped-up yuba after frozen storage was white, and when frozen in gas, it was brown. . From this, it can be said that liquid freezing can suppress discoloration of frozen pumped yuba after frozen storage (that is, before thawing).

  FIG. 8 is a photograph of a pumped-up yuba prepared using trehalose-free soymilk for storage, which was gas-frozen at −80 ° C., degassed, and stored frozen at −20 ° C. for 2 weeks. As can be seen from the comparison between FIG. 6 and FIG. 8, the frozen Kumiage Yuba produced by this method had a very white color of Kumiage Yuba after frozen storage even if trehalose was not added to the soymilk for storage. However, the texture was impaired by frozen storage at −20 ° C. for 2 weeks.

FIG. 9 shows that the pumped-up yuba, whose viscosity and the like were adjusted using trehalose-free soymilk for preservation, was placed in a plastic tube with a lid, gas-frozen at -80 ° C, and then frozen at -80 ° C or -20 ° C. It is a photograph after freeze-preserving for a week and then thawing in running water.
The left plastic tube in FIG. 9 is stored frozen at −80 ° C., and the right plastic tube is stored frozen at −20 ° C. As can be seen from these comparisons, the pumped-up yuba stored frozen at -80 ° C was uniformly smooth, and the pumped-up yuba stored frozen at -20 ° C was partially coagulated.

  In addition, although the above-mentioned test was performed about Kumiage Yuba, it can be easily inferred that the same result can be obtained when the pulled Yuba is frozen. In other words, the lifting yuba is manufactured by scooping up the film after the film is completely formed on the liquid surface of the heated soy milk, so the texture is not as soft as that of the pumped yuba, and the liquid occupying the contained lifting yuba Min (soy milk) is low. Deterioration and discoloration of taste and texture due to freezing and frozen storage are due to denaturation and coagulation of proteins contained in soymilk. Therefore, under conditions that can suppress the deterioration and discoloration of the taste and texture when frozen and frozen preservation of yuba is carried out, the deterioration and discoloration of the taste and texture due to freezing and frozen preservation can also be suppressed in the raised yuba. Can be.

1: rectangular container 1A: alcohol 2: freezing container

Claims (6)

a) a soymilk preparation step of adding 31 to 50% by weight of saccharide to raw soymilk to prepare soymilk for storage;
b) raw yuba manufactured using raw soymilk to which no saccharides are added, and a freezing preparation step of storing the storage soymilk in a freezing container,
c) a freezing step of cooling and freezing the raw yuba and the stored soymilk contained in the freezing container to a temperature range included in a range of -20 ° C to -80 ° C;
d) a freezing storage step of storing the raw yuba and the preserved soymilk in the frozen container in a frozen state in a temperature range included in the range of −18 ° C. to −80 ° C. A method for producing raw yuba. The method for producing frozen raw yuba according to claim 1,
The refrigeration container comprises a sealable container,
In the freezing step, the sealed raw water container is immersed in liquid alcohol cooled to a temperature in the range of -20 ° C to -80 ° C, so that the fresh water leaves and the storage water in the freezer container are immersed. A method for producing frozen raw yuba, comprising freezing soy milk. The method for producing frozen raw yuba according to claim 1 or 2,
The raw yuba is produced using raw soymilk having a predetermined Brix value,
A method for producing frozen raw yuba, wherein the Brix value of the raw soymilk used for the storage soymilk is larger than the Brix value of the raw soymilk of the raw yuba. The method for producing frozen raw yuba according to claim 3,
The Brix value of the raw soymilk used for the storage soymilk is 7 to 9 degrees,
A method for producing frozen raw yuba, wherein the Brix value of the raw soymilk for the raw yuba is 4 to 6 degrees. By heating the raw material soy milk to which the saccharide is not added at a temperature in the range of 70 ° C. to 90 ° C. to scoop up the film formed on the liquid surface of the raw material soy milk and storing the film in the freezing container, Comprising a step of preparing the frozen container containing the raw yuba,
The frozen soybean milk according to any one of claims 1 to 4, wherein the soymilk for preservation at a temperature in the range of 10C to 20C is added to the freezing container to prepare a raw soybean leaf. Manufacturing method. The method for producing frozen raw yuba according to any one of claims 1 to 5,
The method for producing frozen raw yuba, wherein the saccharide is trehalose.