Frozen food and method for producing the same

Abstract

To provide frozen food which can be thawed and tastily taken, and a method for producing the same.SOLUTION: A method for producing frozen food includes: a rice cooking step (S101) of cooking rice using water added with antifreeze protein; a sushi rice step (S106) of mixing the rice obtained by the rice cooking step with blended vinegar; a molding step (S107) of molding the rice obtained by the sushi rice step into a boiled rice ball; a sushi ingredient step (S108) of topping the boiled rice ball obtained by the molding step with sushi ingredients; and a freezing step (S109) of freezing the sushi obtained in the sushi ingredient step while applying vibration to the sushi.SELECTED DRAWING: Figure 1

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 comprising 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 the examples of Patent Document 1 (see paragraphs 0032, 0037, etc.), an antifreeze protein made from radish sprouts is mixed and cooked, then divided into containers of a specified size and frozen at -20 degrees. Patent Document 1 describes dividing the rice into containers, but does not describe how to form the containers. There is also no description of the use of a tunnel freezer or vacuum packing. There is also no description of white waxing.

[0004] In Patent Document 2 (see paragraph 0043, Table 4, etc.), crustacean-derived antifreeze protein is added to rice, which is then cooked, molded into a 20 gram sushi mold, and frozen for three days at -20° C. Patent Document 2 does not mention white waxing, the use of a tunnel freezer, or vacuum packing.

[0005] In addition, additives other than antifreeze proteins may also be added.

[0006] In Patent Document 3 (see paragraphs 0035-0037, Table 7, etc.), antifreeze polysaccharide is added to rice, which is then cooked, and after cooking, the rice is molded, sealed, and then flash frozen at -20°C. However, Patent Document 3 does not specify the processing conditions during molding, nor does it mention a tunnel freezer.

[0007] Patent Document 4 (see paragraphs 0023, 0025, 0026, etc.) describes the manufacture of frozen rice for sushi, in which the rice is cooked in a freezing liquid containing amino acids that have been made into low molecular weight gelatin. After cooking, the rice is pressed into a mold. In Patent Document 4, the rice is slightly degassed, sealed and packaged, and frozen at -40°C to -50°C in a quick freezer, but is not sealed and packaged after freezing. Patent Document 4 does not mention tunnel freezers.

[0008] In Patent Document 5 (see paragraphs 0019, 0023-0025, etc.), oligosaccharides are added to cooked rice and then cooked. Liquid nitrogen ton-el freezing is exemplified as a freezing method, but detailed conditions are not described. It is described that an appropriate amount is packed into a rice ball mold, shaped, wrapped in plastic wrap, placed in a bag, and then left to stand in a freezer at -30°C. Note that Patent Document 5 describes freezing after packaging, and does not describe vacuum packing after freezing. Furthermore, Patent Document 5 does not mention the use of antifreeze ingredients.

[0009] In Patent Document 6 (see paragraphs 0016, 0023, etc.), in the production of frozen rice, cooked rice is shaped into rice balls and flash frozen in a tunnel freezer. In Patent Document 6, a treatment liquid containing sugars (trehalose) is added to the cooked rice. Note that Patent Document 6 does not mention applying vibration during freezing. Also, sugars are not mixed during cooking.

[0010] Patent Document 7 (see paragraphs 0028, 0029, etc.) describes a method for making frozen nigiri sushi. Trehalose (for water retention) is added and the rice is cooked, shaped using a sushi robot, vacuum-packed for bacteriostatic treatment, and then cooled statically. Although Patent Document 7 specifies the freezing conditions, it is not quick freezing, and there is no mention of a tunnel freezer. In addition, the sushi is not vacuum-packed after freezing, but rather is frozen after vacuum packing. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication No. 2010 / 134489 [Patent Document 2] International Publication No. 2007 / 105734 [Patent Document 3] JP 2019-50735 A [Patent Document 4] JP 2009-247294 A [Patent Document 5] Japanese Patent Application Publication No. 06-141797 [Patent Document 6] JP 2012-024056 A [Patent Document 7] JP 2016-202051 A Summary of the Invention [Problem to be solved by the invention]

[0012] For example, frozen foods that contain rice include not only frozen rice alone, but also a variety of other foods such as frozen sushi, frozen seasoned rice, frozen ketchup rice, and frozen rice balls. Some of these frozen foods, such as frozen sushi, are not suitable for reheating in a microwave oven in the first place. Even if a food can be reheated, it may not be possible to reheat a large amount in a microwave oven at once, for example, in a situation where a large number of people are to eat the food at the same time. Also, there are situations in which cooking equipment such as a microwave oven is not available in the first place.

[0013] Therefore, there is a need for technology that allows frozen foods, including rice, to be thawed and eaten deliciously.

[0014] However, when cooked rice is frozen and then thawed, the rice loses moisture and becomes crumbly, like wax. This phenomenon is called white wax. White wax rice is not very tasty. For this reason, technological innovation is required to make frozen foods, including rice, edible after thawing.

[0015] Therefore, an object of the present invention is to provide a frozen food that can be thawed and eaten deliciously, and a method for producing the same. [Means for solving the problem]

[0016] In order to solve the above problems, the present invention has the following features. The present invention provides a method for producing frozen foods, characterized by comprising a rice cooking step of cooking rice using water containing added antifreeze protein, and a freezing step of freezing the rice obtained in the rice cooking step while applying vibration to the rice.

[0017] By adding antifreeze proteins and cooking the rice, the antifreeze proteins bind to ice crystals and inhibit their growth, thereby reducing the deterioration of food quality caused by freezing. In addition, during frozen storage, antifreeze proteins retain water and prevent it from evaporating, preventing the evaporated water vapor from adhering to the food as frost, which helps maintain a moist texture even after thawing.

[0018] In addition, in the present invention, the rice is vibrated in the freezing process, so that each grain of rice remains plump while being frozen.

[0019] In this way, the present invention not only uses antifreeze protein as an ingredient to be mixed in when cooking rice, but also freezes rice using two approaches, namely, the mixing and the freezing method, which involves freezing the rice while applying appropriate vibration.

[0020] The frequency of the vibration applied to the frozen food in the freezing step may be in the range of 25.0 Hz to 35.0 Hz, and preferably, the frequency is in the range of 30.0 Hz to 35.0 Hz. By applying vibrations in this range, each grain of rice remains plump while being frozen.

[0021] In the rice cooking step, the weight of the antifreeze protein added to the water is preferably 0.1 to 0.2 (wt %). Adding antifreeze proteins in this range can prevent food from deteriorating due to freezing.

[0022] The manufacturing process may further include a soaking step in which rice is soaked in water to which an antifreeze protein has been added. In the water immersion step, the weight of the antifreeze protein added to the water is preferably 0.1 to 0.2 (wt %). By adding antifreeze proteins not only in the cooking process but also in the soaking process, the quality of the rice can be improved.

[0023] The above manufacturing process further includes a sushi rice process in which the rice obtained in the rice cooking process is mixed with vinegar, a molding process in which the rice obtained in the sushi rice process is molded into sushi balls, and a sushi topping process in which sushi toppings are placed on the sushi balls obtained in the molding process. In the freezing process, the sushi obtained in the sushi topping process is frozen while being subjected to vibration. The above manufacturing process may further include a packaging step for packaging the frozen sushi obtained in the freezing step. In the packaging process, packaging may be performed by gas replacement.

[0024] By going through these processes, it is possible to provide frozen sushi. In particular, in the freezing process, the sushi is frozen while being subjected to vibration, so it is possible to freeze each individual rice ball while keeping it plump.

[0025] In the rice cooking process, ingredients and / or seasoning liquid may be further added and the rice may be cooked. This makes it possible to enjoy delicious flavored rice, such as seasoned rice or ketchup rice, simply by thawing the rice.

[0026] Preferably, the antifreeze protein used is made from radish sprouts as a raw material. Since it is a natural additive, it is easy for consumers to accept.

[0027] Preferably, the rice used is low amylose rice. This results in even better quality.

[0028] The present invention relates to a frozen food produced by the above-mentioned production method.

[0029] The present invention also provides a frozen food using rice, in which the ratio of the weight of antifreeze protein to the weight of rice is within the range of 0.08 (weight %) to 0.22 (weight %).

[0030] In one embodiment, the present invention is a frozen food product in which sushi toppings are placed on top of a molded sushi rice product made by mixing the above-mentioned rice with vinegar, and then frozen.

[0031] In one embodiment, in the present invention, the above-mentioned rice is cooked while being mixed with ingredients and / or seasonings, and is a frozen food in which the ratio of the weight of antifreeze protein to the weight of rice containing ingredients and / or seasonings is 0.08 (weight %) to 0.22 (weight %). Effect of the Invention

[0032] According to the present invention, rice can be thawed without turning white wax, and a frozen food that can be thawed and eaten deliciously is provided.

[0033] A preferred thawing method is to thaw in the refrigerator compartment (at about 10 degrees) for 4 to 6 hours, but this is not a limitation of the present invention.

[0034] These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0035] [Figure 1] FIG. 1 is a diagram showing a process for producing a rice-containing frozen food (here, frozen sushi) according to one embodiment of the present invention. [Diagram 2]Fig. 2 is a diagram showing the mixing ratios of ingredients at the time of completion of sushi rice produced using a production process according to one embodiment of the present invention. In Fig. 2, the mixing ratios of Comparative Examples 1 to 3 and the Example are shown in weight %. [Diagram 3] FIG. 3 shows the results of a sensory test conducted by three subjects (P1 to P3) on Comparative Examples 1 to 3 produced using white vinegar and Comparative Examples 1 to 3 produced using red vinegar when thawed at -3 degrees for 8 hours. [Figure 4] 4 is a diagram showing the results of a sensory test by one subject (P1) for Comparative Examples 1 to 3 produced with white vinegar, after thawing for 4 hours at 0° C. Note that the subject is not necessarily the same person (same below). [Diagram 5] FIG. 5 shows the results of a sensory test by one subject (P2) for Comparative Examples 1 to 3 produced with white vinegar, after thawing at 3 degrees for 4 hours. [Figure 6] FIG. 6 shows the results of a sensory test conducted by two subjects (P1, P3) on Comparative Examples 1 to 3 produced with white vinegar, after thawing at 10° C. for four hours. [Figure 7] FIG. 7 shows the results of a sensory test conducted by five subjects (P1 to P5) on Comparative Example 3 and the Example produced with white vinegar, after thawing at 10 degrees for 4 hours and 6 hours. [Figure 8] FIG. 8 shows the results of a sensory test conducted by three subjects (P1 to P3) when examples were produced using three different patterns of timing for adding antifreeze protein. [Figure 9] FIG. 9 shows the results of a sensory test conducted by three subjects (P1 to P3) when the example was produced using three types of rice. [Figure 10] FIG. 10 is a diagram showing a process for producing a rice-containing frozen food product (here, cooked rice) according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] 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 an "antifreeze protein-added liquid") is produced (step S101). The antifreeze protein used is preferably an antifreeze protein made from radish sprouts as a raw material, but is not limited thereto. In addition, antifreeze proteins made from fish as raw materials may be used, or antifreeze proteins made from other raw materials may be used.

[0037] The ratio of the antifreeze protein to the water solvent is preferably 0.1 to 0.2% (weight %). For example, a solution is prepared by dissolving 15 g of the antifreeze protein in 8 kg of water. In this case, the ratio of the antifreeze protein to the water is 0.185%.

[0038] In step S102, raw rice is immersed in the antifreeze protein-added liquid. For example, 7 kg of raw rice is immersed 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, and then immersed in the antifreeze protein-added liquid. The volume of the antifreeze protein-added liquid for immersion is not limited because it is discarded in step S103.

[0039] In step S103, the antifreeze protein-added liquid is discarded, and the water from the raw rice is thoroughly drained.

[0040] In step S104, an antifreeze protein-containing liquid is produced in the same manner as in step S101. It goes without saying that the antifreeze protein-containing liquid produced in step S101 may be used as the antifreeze protein-containing liquid.

[0041] In step S105, the soaked raw rice is cooked in the antifreeze protein-added liquid. The volume of the antifreeze protein-added liquid required for cooking is the same as that for cooking normal 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 an appropriate amount of rice cooking oil to make the cooked rice easier to handle, but this is not limited thereto.

[0042] After the rice is cooked, in step S106, vinegar is mixed into the rice to produce sushi rice. Then, the sushi rice is molded into individual sari balls (step S107). Any known method can be used to mold the sari balls. Any known condition can be used to apply pressure to the sari balls.

[0043] Next, sushi toppings are placed on each sari ball (step S108). At this time, the sari ball and toppings may be appropriately pressed by a person or a robot.

[0044] The sushi made in step S108 is frozen while being subjected to vibration (S109). For example, a tunnel freezer can be used, which can quickly freeze food while vibrating it. A tunnel freezer is a machine that has a tunnel shape that food can pass through, and can quickly freeze food by blowing cold air directly onto the food on the conveyor. By vibrating the conveyor, the food can be quickly frozen.

[0045] The tunnel freezer conditions were: temperature set at -40 degrees, transit time 28 minutes, and vibration frequency 30.0 Hz. Of course, these setting conditions are merely an example, and the setting conditions for the tunnel freezer may be a set temperature of -35°C to -45°C, a transit time of 25 to 31 minutes, and a vibration frequency in the range of 25.0 Hz to 35.0 Hz. More preferably, the tunnel freezer conditions are set at a temperature of -35°C to -40°C, a transit time of 25 to 28 minutes, and a vibration frequency in the range of 30.0 Hz to 35.0 Hz.

[0046] The frozen sushi made in step S109 is packed into packages, an oxygen scavenger is injected, and the package is vacuum-packed while replacing the gas, completing the individually packaged frozen sushi (step S110). In addition, multiple frozen sushi may be packed together in a plastic container or other package and vacuum-packed while replacing the gas. As a packing method, any known method can be used.

[0047] The frozen sushi produced in the manner described above can be thawed in the refrigerator compartment of a typical household refrigerator (at around 10 degrees) for 4 to 6 hours, allowing the sushi rice to thaw without turning white wax.

[0048] (Examples and Comparative Examples 1 to 3) In the manufacturing method shown in Figure 1, an example is shown in which antifreeze protein is dissolved in the water to be cooked. In the example, Kaneka Foods Corporation's product name "Kaneka Antifreeze Protein KR1" and the name "radish sprouts extract (food additive)" are used as the antifreeze protein. 15g of antifreeze protein was dissolved in 8kg of water and used for cooking.

[0049] The rice was cooked with oligosaccharide dissolved in the water used for cooking, and the resultant rice was designated Comparative Example 1. In Comparative Example 1, the rice was cooked using a liquid in which 156 g of oligosaccharide was dissolved in 8 kg of water.

[0050] The rice was cooked by dissolving oligosaccharides and gelatin in the water used for cooking, and the resulting rice was designated Comparative Example 2. In Comparative Example 2, the rice was cooked using a liquid in which 156 g of oligosaccharides and 139 g of gelatin were dissolved in 8 kg of water.

[0051] Gelatin and the sweetener trehalose were dissolved in the water used for cooking, and the rice was cooked as Comparative Example 3. In Comparative Example 3, rice was cooked using a liquid in which 87 g of gelatin and 69 g of the sweetener trehalose were dissolved in 8 kg of water.

[0052] In the examples and comparative examples 1 to 3, the mixing ratios of the raw materials in the state of sushi rice after adding the combined vinegar are as shown in FIG. That is, in the example, the blending ratio of antifreeze protein in the sushi rice was 0.1% ("% by weight", the same applies below). In addition, the antifreeze protein content without the vinegar mixture is 0.1 ÷ (100 - 11.8) = approximately 0.113%.

[0053] Similarly, in Comparative Example 1, the blending ratio of oligosaccharides was 0.9%. In Comparative Example 2, the blending ratio of oligosaccharide was 0.9%, and the blending ratio of gelatin was 0.8%. In Comparative Example 3, the blending ratio of gelatin was 0.5%, and the blending ratio of the sweetener trehalose was 0.4%.

[0054] The examples and comparative examples 1 to 3 were made into sari balls and frozen under the conditions shown in step S108. First, the results of verifying which of Comparative Examples 1 to 3 is the most suitable frozen sushi rice for frozen sushi will be described with reference to Figs. 3 to 6.

[0055] Comparative Examples 1 to 3 were thawed at -3 degrees for 8 hours, and three subjects conducted a sensory test on the flavor, texture, and appearance (Figure 3). Good was scored as 3 points, average as 2 points, and bad as 1 point. In the experiment in Figure 3, white vinegar and red vinegar were used as the combined vinegar. As a result, for both white vinegar and red vinegar, Comparative Example 2 was rated at a total of 27 points, Comparative Example 1 at 18 points, and Comparative Example 3 at 9 points.

[0056] Comparative Examples 1 to 3 were thawed at 0°C for 4 hours, and a sensory test was carried out by one subject (FIG. 4). Note that the combined vinegar was evaluated using white vinegar alone (same below). As a result, Comparative Example 3 was rated at 9 points, Comparative Example 1 at 8 points, and Comparative Example 2 at 6 points.

[0057] Comparative Examples 1 to 3 were thawed at 3 degrees for 4 hours, and a sensory test was carried out by one subject (FIG. 5). As a result, Comparative Example 1 was rated at 8 points, Comparative Example 3 at 6 points, and Comparative Example 2 at 5 points.

[0058] Comparative Examples 1 to 3 were thawed at 10° C. for 4 hours, and a sensory test was carried out by two subjects (FIG. 6). As a result, Comparative Example 3 was rated at 15 points, Comparative Example 1 at 12 points, and Comparative Example 2 at 10 points.

[0059] Since the temperature of the refrigerator compartment is about 10 degrees, Comparative Example 3, which received high marks when thawed at 10 degrees, was used as a comparative example for comparison with the examples.

[0060] As shown in FIG. 7, when the Example and Comparative Example 3 were thawed at 10 degrees for 4 hours, the Example was rated at 37 points and the Comparative Example 3 was rated at 33 points. The rice in Comparative Example 3, which was thawed at 10 degrees for 4 hours, was evaluated as having no luster, feeling hard, and lacking cohesion. In other words, there is a possibility that the rice in Comparative Example 3 has turned white waxy. On the other hand, the rice in the example thawed at 10 degrees for 4 hours was rated as having less luster, but the rice was easy to separate and eat, and had a chewy texture. In other words, it seems that the rice in the example did not turn white waxy.

[0061] Furthermore, when the Example and Comparative Example 3 were thawed at 10 degrees for 6 hours, the Example received 42 points and the Comparative Example 3 received 36 points. Comparative Example 3, in which the product was thawed at 10 degrees for six hours, was rated as having almost the same results as the four-hour experiment. On the other hand, the rice in the example thawed at 10 degrees for 6 hours had a chewy texture without a dry feeling, and the rice did not clump together when eaten, but rather loosened moderately, making it taste better. In other words, the rice in the example did not turn white.

[0062] From the above experiments, we found that by freezing rice cooked with antifreeze protein and then thawing it at 10 degrees for 4 to 6 hours, we can provide sushi that tastes delicious.

[0063] (Timing of using antifreeze protein-added liquid) Next, we conducted an experiment to compare the timing of adding antifreeze protein during rice cooking (Figure 8). Sensory tests were conducted for three patterns: cooking rice using an antifreeze protein solution during soaking and cooking (the process pattern in Figure 1), cooking rice using an antifreeze protein-added liquid only during cooking, and cooking rice using an antifreeze protein-added liquid only during soaking.

[0064] As a result, the pattern in which antifreeze protein solution was used during soaking and cooking was given 23 points, the pattern in which antifreeze protein-added liquid was used only during cooking was given 18 points, and the pattern in which antifreeze protein-added liquid was used only during soaking was given 10 points. This shows that it is most preferable to use an antifreeze protein solution when soaking and cooking rice, and secondly, it is preferable to use an antifreeze protein-added liquid only when cooking rice. Therefore, it is found that it is good to use an antifreeze protein-added liquid at least when cooking rice.

[0065] (Type of rice) Next, a comparative experiment was conducted in which the type of rice used was changed (Figure 9). Sensory tests were conducted on three patterns: when using rice for sushi rice (so-called old rice), when using low-amylose rice (here, "Yumepirika"), and when using rice other than low-amylose rice. Low-amylose rice refers to rice with an amylose content of approximately 3 to 17%.

[0066] As a result, the score for the product using low amylose rice was 23 points, the score for the product using non-low amylose rice was 18 points, and the score for the product using old rice was 16 points. The results of this experiment showed that it is preferable to use low-amylose rice, but that other types of rice are not significantly worse in quality.

[0067] (Other embodiments) In the above embodiment, a method for producing frozen sushi was described, but the present invention relates to a frozen food containing rice, and is not limited to frozen sushi. The present invention is a frozen food using rice that has been boiled with the addition of antifreeze protein. Therefore, rice itself may be made into a frozen food. When making rice itself into a frozen food, it is not seasoned after cooking, and is frozen after being packed into containers or the like. In addition, the cooked rice may be seasoned and then packed into containers before being frozen. In addition, the rice may be frozen after being cooked and processed into rice balls by adding ingredients.

[0068] FIG. 10 is a diagram showing a process for producing frozen foods using rice seasoned during cooking, such as seasoned rice and ketchup rice. Steps S201 to S204 in FIG. 10 are the same as steps S101 to S104 in FIG.

[0069] In step S205, the soaked raw rice is cooked with an antifreeze protein-added liquid, ingredients, and seasonings. In this step, a recipe suitable for the intended cooked rice, ketchup rice, etc. is used.

[0070] After cooking, the rice is placed in a container (step S206), and then, as in the case of FIG. 1, it is frozen in a tunnel freezer (step S207) and packaged (step S208).

[0071] This manufacturing method makes it possible to produce frozen foods, including flavored rice such as delicious seasoned rice and ketchup rice, simply by thawing the food.

[0072] (Freezing method) In the above embodiment, the rice is frozen using a tunnel freezer. It is believed that freezing the rice in a tunnel freezer while applying vibrations allows each grain of rice to be frozen in a plump state.

[0073] As a vibration condition for this purpose, as described above, the vibration frequency should be within the range of 25.0 Hz to 35.0 Hz, preferably within the range of 30.0 Hz to 35.0 Hz, and in one embodiment, 30.0 Hz.

[0074] It should be noted that any machine other than a tunnel freezer may be used for freezing food as long as it is capable of quickly freezing the food by applying vibration and blowing cold air onto the food.

[0075] (Timing of addition) In the above embodiment, the most preferable timing for adding the antifreeze protein is when the rice is soaked and when it is cooked, and it is recommended to add it at least when it is cooked. However, if antifreeze protein is added to cooked rice, a certain effect of preventing white waxiness after thawing can be expected, so adding the antifreeze protein only when it is soaked is not excluded in the present invention.

[0076] That is, the present invention makes it possible to prevent white wax formation by using an antifreeze protein-added liquid during soaking and / or cooking of rice.

[0077] (Concentration of antifreeze protein added liquid) In the above embodiment, a solution containing 0.1875% (wt%) of antifreeze protein dissolved in water is used during soaking and cooking. This wt% is merely an example and is not intended to be limiting in the present invention.

[0078] It is preferable to cook rice using a liquid in which at least 0.1 to 0.2% of antifreeze protein is dissolved relative to the weight of the water.

[0079] (Rice blend ratio after cooking) In the above embodiment, 7 kg of raw rice was cooked using an antifreeze protein-added liquid used for soaking (discarded after soaking) and an antifreeze protein-added liquid used during cooking (15 g of antifreeze protein added to 8 kg of water). This varies depending on the type of rice, the environment, and the season, but if you cook rice with this mixture, you will end up with 15kg of cooked rice.

[0080] From experience, it has been found that if 7 kg of raw rice is soaked and then cooked in 8 kg of water, the resulting rice will weigh 15 kg. Therefore, if we simplify and assume that the antifreeze proteins contained in the antifreeze protein-added liquid used during soaking are not absorbed by the raw rice, then 15 kg of cooked rice will contain 15 g of antifreeze proteins, and the ratio of antifreeze proteins in cooked rice will be 0.1% (by weight).

[0081] However, in an embodiment in which an antifreeze protein-added liquid is used even during soaking, the antifreeze protein is absorbed into the raw rice during soaking. Although it depends on the conditions, the weight of 7 kg of raw rice after soaking is approximately 9.3 kg, so 2.3 kg of the antifreeze protein-added liquid is absorbed by the raw rice. The weight of the antifreeze protein contained in the 2.3 kg of antifreeze protein-added liquid is 4.3 g. Therefore, cooked rice will contain 15g + 4.3g = 19.3g of antifreeze protein, so the proportion of antifreeze protein in cooked rice will be approximately 0.128% (weight%).

[0082] From the above considerations, it can be seen that the ratio of the weight of antifreeze protein to the weight of cooked rice is preferably 0.08% to 0.22%.

[0083] Also, when cooking rice mixed with ingredients and / or liquid seasoning, the ratio of the weight of the antifreeze protein to the weight of the cooked rice containing the ingredients and / or liquid seasoning is preferably 0.08% to 0.22%.

[0084] Although the present invention has been described in detail above, the above description is merely illustrative of the present invention in every respect 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. The constituent elements of the invention disclosed in this specification are each considered to be independent and stand alone as a single invention. Inventions in which the constituent elements are combined in any combination method are also included in the present invention. The specific expressions in this specification are merely illustrative, and the present invention also includes those that conceptualize the illustrative expressions. [Industrial Applicability]

[0085] The present invention relates to frozen foods and is industrially applicable.

Claims

1. A rice cooking process in which rice is cooked using water to which an antifreeze protein has been added; A method for producing a frozen food, comprising: a freezing step of freezing the rice obtained in the rice cooking step while applying vibration thereto.

2. 2. The method for producing a frozen food according to claim 1, wherein the frequency of the vibration applied to the frozen food in the freezing step is in the range of 25.0 Hz to 35.0 Hz.

3. The method for producing frozen foods according to claim 2, wherein the frequency is in the range of 30.0 Hz to 35.0 Hz.

4. 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 0.2 (wt%).

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

6. 6. The method for producing a frozen food according to claim 5, wherein the weight of the antifreeze protein added to the water in the immersion step is 0.1 to 0.2 (wt%).

7. moreover, A sushi rice process in which vinegar is mixed with the rice obtained in the rice cooking process; A forming process of forming the rice obtained in the sushi rice process into a sushi ball; and a sushi topping process for placing sushi toppings on the sari ball obtained in the molding process.

2. The method for producing a frozen food according to claim 1, wherein in the freezing step, the sushi obtained in the sushi filling step is frozen while being subjected to vibration.

8. 8. The method for producing a frozen food according to claim 7, further comprising a packaging step of packaging the frozen sushi obtained in the freezing step.

9. The method for producing a frozen food according to claim 8, wherein the packaging step involves packaging by gas replacement.

10. The method for producing a frozen food according to claim 1 , wherein in the rice cooking step, ingredients and / or seasoning liquid are further added and then the rice is cooked.

11. 2. The method for producing a frozen food according to claim 1, wherein the antifreeze protein is made from radish sprouts.

12. 2. The method for producing a frozen food according to claim 1, wherein the rice used is low-amylose rice.

13. A frozen food produced by the method according to claim 1.

14. The frozen food uses rice in which the ratio of the weight of antifreeze protein to the weight of rice is in the range of 0.08 (wt%) to 0.22 (wt%).

15. The frozen food according to claim 14, characterized in that the sushi rice product is made by mixing rice with vinegar and then placing sushi toppings on the shaped sushi rice product and then freezing it.

16. The frozen food according to claim 14, characterized in that the rice is cooked while being mixed with ingredients and / or seasonings, and the ratio of the weight of the antifreeze protein to the weight of the rice containing the ingredients and / or seasonings is 0.08 (weight %) to 0.22 (weight %).

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