Frozen food manufacturing method

Abstract

To provide a method for producing frozen food suitable for freezing cooked rice mixed with antifreeze protein. [Solution] This is a method for producing frozen foods, which includes a rice cooking process (S104) in which rice is cooked using water to which antifreeze protein has been added, a forming process (S106) in which the rice obtained in the rice cooking process is formed into sari balls, a freezing process (S107) in which the sari balls obtained in the forming process are frozen, and a glazing process (S108) in which a mist of liquid is sprayed onto the surface of the sari balls frozen in the freezing process to freeze them.

Description

[Technical Field]

[0001] The present invention relates to a method for producing frozen foods, and more particularly to a method for producing frozen foods containing rice. [Background technology]

[0002] Conventionally, as described in Patent Documents 1 and 2, methods have been proposed for producing frozen foods containing rice by mixing antifreeze protein into rice during cooking, cooking the rice, and freezing it.

[0003] In Patent Document 1 (see paragraph 0043, Table 4, etc.), rice is cooked with an antifreeze protein derived from crustaceans, and after cooking, it is molded using a 20 gram sushi mold, frozen at -20°C for 3 days, and then transferred to -10°C and frozen for 5 days.

[0004] In Patent Document 2 (see paragraphs 0032, 0037, etc.), in the examples, rice is cooked after mixing with an antifreeze protein made from radish sprouts, and the cooked rice is divided into 100g portions and stored in a refrigerator-freezer at -20°C. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2007 / 105734 [Patent Document 2] International Publication No. 2010 / 134489 Summary of the Invention [Problem to be solved by the invention]

[0006] Although both Patent Documents 1 and 2 describe a method of mixing antifreeze proteins with rice, cooking the rice, and freezing it, they do not describe a freezing method suitable for freezing rice that has been mixed with antifreeze proteins and cooked, solidifying it into a ball-like shape.

[0007] Therefore, an object of the present invention is to provide a method for producing a frozen food suitable for freezing rice that has been mixed with an antifreeze protein and then cooked. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention has the following features. The present invention provides a method for producing frozen food, comprising a rice cooking step of cooking rice using water to which an antifreeze protein has been added, a freezing step of freezing the rice obtained in the rice cooking step, and a glazing step of spraying a mist of liquid onto the surface of at least a portion of the rice frozen in the freezing step, thereby freezing the rice.

[0009] Preferably, the method further comprises a molding step of molding the rice cooked in the rice cooking step into a predetermined shape, the freezing step freezes the rice molded in the molding step, and the glazing step freezes by spraying a mist of liquid onto at least a part of the surface of the molded and frozen rice.

[0010] Preferably, in the freezing step, the rice is frozen by applying cold air to the rice and vibrating the rice.

[0011] Preferably, the frequency of the vibration applied to the cooked rice in the freezing step is in the range of 25.0 Hz to 35.0 Hz.

[0012] Preferably, the liquid sprayed in the glazing step is purified water.

[0013] Preferably, the liquid to be sprayed in the glazing step is water to which an antifreeze protein has been added.

[0014] Preferably, in the molding process, 0.5 g / cm 3 ~1.2g / cm 3 It is best to shape the rice to the desired density. More preferably, in the molding process, 0.6 g / cm 3 ~1.0g / cm 3 It is best to shape the rice to the desired density.

[0015] Preferably, the weight of the antifreeze protein added to water in the rice cooking step is 0.1 to 0.3 (wt %).

[0016] Preferably, the method further includes a soaking step of soaking rice in water to which an antifreeze protein has been added.

[0017] Preferably, the weight of the antifreeze protein added to the water in the water immersion step is 0.1 to 0.3 (wt %). [Effects of the Invention]

[0018] According to the present invention, a method for producing a frozen food suitable for freezing rice that has been mixed with an antifreeze protein and cooked using a glazing step is provided.

[0019] The objects, features, configurations, operations, and effects of the present invention and embodiments of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a diagram showing a process for producing a frozen food product containing rice (here, frozen sushi) according to one embodiment of the present invention. [Figure 2] Fig. 2 is a diagram showing the results of a sensory test of an example of the present invention. Fig. 2 is used to examine the appropriate density of cooked rice in Shari-dama. [Figure 3] 3 is a diagram showing the results of a sensory test of an example of the present invention. The effect of the glazing treatment will be examined using FIG. [Figure 4] FIG. 4 is a diagram showing the calculation results of the size and volume of the mold used in the sensory test of one example of the present invention. [Figure 5] FIG. 5 is a photograph of the frozen Shari balls used in the sensory test of one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] A method for producing a frozen food (frozen sushi) according to one embodiment of the present invention will be described with reference to FIG. First, a liquid in which an antifreeze protein is added to water (hereinafter referred to as "antifreeze protein-added liquid") is produced (step S101). The antifreeze protein used is preferably an antifreeze protein made from radish sprouts, but is not limited thereto. It should be noted that antifreeze proteins made from fish may be used, or antifreeze proteins made from other raw materials may be used.

[0022] The ratio of antifreeze protein to water, which serves as the solvent, is preferably 0.1 to 0.3% (weight %). For example, a solution is prepared by dissolving 15 g of antifreeze protein in 8 kg of water. In this case, the ratio of antifreeze protein to water is 0.185%. In the examples shown in Figs. 2 and 3 described below, a liquid containing 0.2% antifreeze protein was used.

[0023] In step S102, raw rice is soaked in the antifreeze protein-added liquid. For example, 7 kg of raw rice is soaked in the antifreeze protein-added liquid. The raw rice is preferably, but not limited to, pre-washed rice. If pre-washed rice is not used, the raw rice is washed once and thoroughly drained before being soaked in the antifreeze protein-added liquid. The volume of the antifreeze protein-added liquid for immersion is not limited in the present invention because it is discarded in step S103.

[0024] In step S103, the liquid containing the antifreeze protein is discarded, and the water from the raw rice is thoroughly drained.

[0025] In step S104, the soaked raw rice is cooked in the liquid containing antifreeze proteins. The volume of the liquid containing antifreeze proteins required for cooking the rice is the same as that required for cooking regular sushi rice, but is determined appropriately taking into account the season, the type of raw rice, etc. At this time, it is advisable to add rice cooking oil as needed to make the cooked rice easier to handle, but this is not limited thereto.

[0026] After the rice is cooked, in step S105, the rice is mixed with vinegar to produce sushi rice. Note that if the recipe does not require mixing in vinegar, step S105 is omitted.

[0027] Then, the sushi rice is formed into individual sari balls, and toppings are placed on them as needed (step S106). Any known method can be used to form the sari balls. Any known conditions can be used to apply pressure to the sari balls. The sari balls and toppings can be squeezed by a person or a robot as needed. The sushi to be produced is not limited to nigiri sushi, and any type of sushi can be used, such as rolled sushi, temari sushi, or pressed sushi.

[0028] The sushi made in step S106 is frozen (S107). Any known freezing method can be used, but for example, it is good to use a tunnel freezer (registered trademark) that exposes the sushi to cold air and vibrates it to quickly freeze the sushi.

[0029] The conditions for setting the tunnel freezer (registered trademark) were a set temperature of -40°C, a transit time of 28 minutes, and a vibration frequency of 30.0 Hz. Of course, these setting conditions are merely an example, and the setting conditions for a tunnel freezer (registered trademark) should be a set temperature of -35 to -45 degrees, a transit time of 25 to 31 minutes, and a vibration frequency in the range of 25.0 to 35.0 Hz. More preferably, the conditions for setting the tunnel freezer (registered trademark) are a set temperature of -35 to -40 degrees, a transit time of 25 to 28 minutes, and a vibration frequency in the range of 30.0 to 35.0 Hz.

[0030] The sushi frozen in step S107 is glazed using a liquid containing antifreeze protein (S108). Glazing is the process of forming a thin layer of ice on the surface of frozen food. Spray the antifreeze protein-added liquid onto the frozen sushi and freeze it. This will create a thin layer of ice on the surface of the sushi. Repeat this process as many times as necessary to achieve the desired thickness of glaze.

[0031] Finally, the frozen sushi made in step S108 is packed into a pack, an oxygen absorber is injected, and the pack is vacuum-packed while replacing the gas, thereby completing the individually packaged frozen sushi (step S109). Alternatively, multiple frozen sushi pieces can be packed together in a plastic container or other container and vacuum-packed while replacing the gas. Any other known packing method can be used. For example, the components may be vacuum-packaged individually or in a container without using gas exchange.

[0032] After the sari balls are glazed, sushi toppings may be placed on the sari balls and frozen.

[0033] By thawing the frozen sushi produced in the manner described above for 3 to 5 hours in the refrigerator compartment of a typical household refrigerator (at around 10 degrees), the sushi rice will thaw without turning white and waxy, making it delicious to eat. [Example]

[0034] Antifreeze protein is dissolved in boiling water to produce an antifreeze protein-added liquid. Here, the antifreeze protein used is "Kaneka Antifreeze Protein KR1," a product name of Kaneka Foods Corporation, and "Radish sprouts extract (food additive)." The concentration of the antifreeze protein-added liquid is 0.2% antifreeze protein relative to the water.

[0035] To manufacture the Shari-dama, a mold with the dimensions shown in Figure 4 was used. As shown in Figure 4, the volume of the mold was approximately 22.44 cm 3 is. Sample 1 was made by placing 15 grams of cooked rice in the mold. To determine the density of the cooked rice, the ratio (weight of cooked rice) divided by (volume of mold) was calculated as shown in Figure 4. Sample 1 had a density of 0.67 g / cm 3 This is what happened. Sample 2 was made by placing 18 grams of cooked rice in the mold. Sample 2 had a density of 0.80 g / cm 3 This is what happened. Sample 3 was made by placing 25 grams of cooked rice in the mold. Sample 3 had a density of 1.12 g / cm 3 This is what happened.

[0036] In FIG. 2, the samples labeled 15g, 18g, and 25g correspond to the above samples 1 to 3, respectively. In addition, in FIG. 2, for samples 1 to 3, cooking methods A, B, C, and D were used as variations in the presence or absence of antifreeze protein and cooking methods.

[0037] A was cooked using an antifreeze protein-added liquid containing 0.2% antifreeze protein relative to the weight of the water, without soaking. B was soaked overnight in an antifreeze protein-added liquid containing 0.2% antifreeze protein relative to the weight of the water, and then cooked in the antifreeze protein-added liquid. C was cooked in tap water without using antifreeze protein or soaking. D was soaked in tap water overnight without using antifreeze protein and cooked in tap water. The tap water used was tap water from 4-16 Shikinaicho, Izumiotsu City, Osaka Prefecture.

[0038] The cooked rice was pressed into balls using the above-mentioned mold, frozen, and stored for at least 48 hours. Sensory tests were then conducted on the balls after thawing them in a 10°C thawing cabinet for 1, 2, and 3 hours. The sensory test was carried out to check the degree of thawing and white waxiness. The thawing state was evaluated as follows: (1) to (5). Note that (1) indicates the number 1 in the circle in Figure 1 (same below).

[0039] (Evaluation of thawing condition) (1) It's not solved. It's all hard. (2) The outside is melted and the center is hard. (3) It has thawed but is still hard and inedible. (4) Thawed but still cold and edible. (5) It's soluble and edible.

[0040] The evaluation of white waxing is as follows (1) to (5). (1) Hard and completely devoid of moisture. (2) Hard: There is no moisture in the center. There is a core. (3) It is not hard. There is still some moisture in the center. You can feel the core. (4) Soft - There is still moisture in the center. You can't feel the core. (5) Soft - Moisture remains in the center. There is no core at all and it is delicious.

[0041] As shown in Figure 2, two hours after the start of thawing, the 15g, 18g, and 25g samples were insufficiently thawed regardless of cooking method A to D. Three hours after the start of thawing, the 15g and 18g samples cooked using methods A and B were completely thawed and rated 5, meaning they were edible (the area circled in Figure 2). Furthermore, for the evaluation of white waxing, 3 hours after the start of thawing, the 15g and 18g samples were rated as (4) when cooked using methods A and B (the area circled in Figure 2). As shown in Figure 2, cooking methods A and B were evaluated the same for both the degree of thawing and white waxing, but the taste of the food was that cooking method B, which involved soaking the rice overnight, tasted better.

[0042] For the 25g samples cooked using methods A and B, the thawing state was evaluated as (4) three hours after the start of thawing. Therefore, it can be inferred that if the thawing time is extended a little more, the thawing of the 25g sample will also progress. For the 25g samples cooked using methods A and B, the evaluation of white waxiness was (3) three hours after the start of thawing.

[0043] From the experiment in Figure 2, it was found that the densities of Samples 1 and 2, 15g and 18g, were sufficient to be thawed and enjoyed after approximately 3 hours. The density of Sample 1 was 0.67g / cm 3 and the density of sample 2 is 0.80 g / cm 3 The density of 25 g of Sample 3 was 1.12 g / cm 3 However, it is possible to eat it if the thawing time is extended.

[0044] Therefore, although the present invention is not limited to the density, it is preferably 0.80 g / cm 3 For example, the density of rice, expressed as the weight of rice relative to the volume of the mold, is 0.5 g / cm 3 ~1.2g / cm 3 Preferably, it is 0.6 g / cm 3 ~1.0g / cm 3 It would be good if that were the case.

[0045] The experiment in Figure 2 was conducted to determine the density of the sarira ball. The feature of the present invention is that the sarira ball is glazed, so the density of the sarira ball does not limit the present invention.

[0046] Next, the results of the sensory test with and without glaze treatment will be explained with reference to Figure 3. Figure 3 uses the 18g sample Shari-tama used in the experiment in Figure 2. The rice used for the Shari-tama was soaked overnight in an antifreeze protein-added liquid containing 0.2% antifreeze protein relative to the weight of water, and then cooked in the antifreeze protein-added liquid. The sample did not contain mixed vinegar or toppings.

[0047] The rice cooked in this way was made into sari balls and frozen (S107 in Figure 1). Then, for sample a, the sarira ball was glazed using a liquid containing 0.2% antifreeze protein (S108 in Figure 1). For sample b, the sarira ball was glazed using purified tap water using a filter-type water purifier (S108 in Figure 1). Sample c is the sari ball that was frozen in S107 of Figure 1 and was not glazed.

[0048] In samples a and b, the mist of liquid is sprayed from above the relic ball, so no liquid adheres to the bottom of the relic ball.

[0049] In Figure 3, the finished samples were stored for 48 hours or more and then thawed for 1 to 8 hours in a thawing cabinet at 10°C, and then a sensory test was conducted on the samples. The evaluation of the degree of thawing and white waxing in the sensory test in Figure 3 was the same as in Figure 2.

[0050] Three hours after the start of thawing, samples a, b, and c are ready to eat. Even after 4 and 5 hours had passed since the start of thawing, the samples a and b of the examples were rated as (5) in terms of white waxing. On the other hand, for sample c, which is a comparative example, the evaluation of white waxing remains at (4) even after 3 hours, 4 hours, and 5 hours have passed since the start of thawing.

[0051] The sensory test in Figure 3 shows that by freezing the Shari balls and then glazing them with a liquid containing antifreeze protein or with water without it, it was possible to prevent them from turning white and maintain them in a delicious, edible state for 3 to 5 hours after thawing began. Sample c, which was not glazed, was soft and had moisture in the center, so there was no core to it, but it was inferior to the glazed sample in terms of palatability.

[0052] After six hours of thawing, the samples gradually began to dry out and turn white and waxy, and the flavor of all three samples a, b, and c began to deteriorate.

[0053] The liquid used for the glazing process may be a liquid containing antifreeze protein, purified water, or tap water.

[0054] Thus, in the present invention, by cooking rice using an antifreeze protein-added liquid, it is possible to prevent the rice from turning white and waxy even after thawing. In addition, by applying a glaze treatment to the rice balls, it is possible to prevent the rice balls from drying out or turning white and waxy even after thawing. It is presumed that the liquid film around the rice balls created by the glaze treatment is absorbed by the rice, allowing the rice balls to maintain an appropriate level of moisture for a long time, making them delicious to eat.

[0055] In the above embodiments and examples, rice is formed into a sarira ball, but the shape of the formed rice is not limited to a sarira ball. If rice is formed into a predetermined shape or placed in a predetermined container, and then frozen, and then a liquid mist is sprayed onto the surface of the frozen rice to perform a glaze treatment, the rice can be similarly kept in a state of appropriate moisture for a long time after thawing, making it delicious to eat.

[0056] Therefore, the present invention is characterized by performing a glaze treatment in which rice cooked in a liquid containing antifreeze protein is frozen and then a mist of liquid is sprayed onto the surface of the frozen rice to freeze it. The liquid to be sprayed may be water (water containing no additives) or water to which antifreeze protein has been added (liquid containing antifreeze protein). In addition, an additive suitable for the glaze treatment may be added to the liquid to be sprayed.

[0057] It is acceptable for there to be areas where the mist liquid cannot be sprayed, such as the bottom of the frozen rice or the bottom of the rice. In other words, the glaze treatment is sufficient as long as it is applied to at least a portion of the surface of the frozen rice. Alternatively, the frozen rice or the mist liquid may be lifted up and sprayed onto the bottom, thereby glazing the entire surface.

[0058] Although the present invention has been described in detail above, the above description is merely illustrative of the present invention in all respects and is not intended to limit its scope. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention. Each of the constituent elements of the invention disclosed in this specification is considered to be an independent, stand-alone invention. Inventions that combine the constituent elements in any manner are also included in the present invention. The specific expressions in this specification are merely examples, and the present invention also includes those that conceptualize these exemplary expressions. [Industrial Applicability]

[0059] The present invention relates to frozen foods and is industrially applicable.

Claims

1. a rice cooking step of cooking rice using water to which antifreeze protein has been added; a freezing step of freezing the rice obtained in the rice cooking step; and a glaze treatment step of spraying a mist of liquid onto the surface of at least a portion of the rice frozen in the freezing step to freeze the rice.

2. The method further includes a forming step of forming the rice cooked in the rice cooking step into a predetermined shape, In the freezing step, the rice molded in the molding step is frozen, 2. The method for producing a frozen food according to claim 1, wherein the glazing step involves spraying a mist of liquid onto at least a portion of the surface of the molded and frozen rice to freeze it.

3. 2. The method for producing a frozen food according to claim 1, wherein the freezing step freezes the rice by vibrating the rice while applying cold air to the rice.

4. 4. The method for producing a frozen food according to claim 3, wherein the frequency of the vibration applied to the cooked rice in the freezing step is in the range of 25.0 Hz to 35.0 Hz.

5. In the glazing process, the liquid to be sprayed is purified water. A method for producing the frozen food according to claim 1.

6. 2. The method for producing a frozen food according to claim 1, wherein the liquid sprayed in the glazing step is water to which an antifreeze protein has been added.

7. In the molding process, 0.5 g / cm 3 ~1.2g / cm 3 3. The method for producing a frozen food according to claim 2, wherein the rice is molded to a density of 1000 kJ / g.

8. In the molding process, 0.6 g / cm 3 ~1.0 g / cm 3 8. The method for producing a frozen food according to claim 7, wherein the rice is molded to a density of 1000 kJ / g.

9. 2. The method for producing a frozen food according to claim 1, wherein the weight of the antifreeze protein added to the water in the rice cooking step is 0.1 to 0.3 (wt %).

10. The method for producing a frozen food according to claim 1, further comprising a soaking step of soaking rice in water to which the antifreeze protein has been added.

11. 11. The method for producing a frozen food according to claim 10, wherein the weight of the antifreeze protein added to the water in the immersion step is 0.1 to 0.3 (wt %).

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