Method for producing cooked rice

Abstract

To further increase the reliability of long-term storage of cooked rice without lengthening a production process.SOLUTION: A method for producing cooked rice includes: a soaking step (S1) of soaking rice in water at a weight ratio of 30 to 33% of the rice weight; a rice cooking step (S2) of cooking the rice subjected to the soaking step after adding water at a weight ratio of 90 to 100% of the rice weight; a first cooling step (S3) of cooling the center temperature of the rice subjected to the rice cooking step to 40 to 50°C; a stirring step (S4) of adding a soybean-derived β-amylase enzyme preparation to the cooked rice subjected to the cooling step and having a center temperature of 40 to 50°C at a weight ratio of 1.0 to 1.8% of the cooked rice weight and mixing them; a second cooling step (S5) of cooling the cooked rice subjected to the stirring step to below 20°C; a bactericidal step (S6) of storing the cooked rice subjected to a packaging step at 60 to 70°C for 9 to 13 hours; a packaging step (S7) of sealing and packaging the cooked rice subjected to the bactericidal step; and a sterilization step (S8) of storing the cooked rice subjected to the packaging step for 10 to 15 minutes at a center temperature of 100 to 110°C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing cooked rice. [Background technology]

[0002] Hardtack, canned foods, retort pouch foods, instant foods, and the like are known as emergency foods that can be stored for long periods of time. A method for producing cooked rice that can be stored for long periods of time, maintains its color, and can be eaten even when water and heating equipment are unavailable, and a method for producing the same, have been proposed. The cooked rice is produced by a production method that includes the following steps: a soaking process in which rice is soaked in water and a food additive acidulant preparation; a rice cooking process in which the soaked rice and water containing the food additive acidulant preparation are cooked; an enzyme addition process in which a predetermined amount of enzyme preparation is added to the cooked rice while maintaining the cooked rice at a predetermined temperature; a sealing process in which the cooked rice containing the enzyme preparation after the enzyme addition process is placed in a heat-resistant tray and sealed; a aging process in which the cooked rice in the sealed heat-resistant tray after the sealing process is stored under predetermined temperature conditions for a certain period of time to mature; and a sterilization process in which the cooked rice in the heat-resistant tray after the aging process is heated for a predetermined period of time while maintaining the temperature of the center of the cooked rice at a predetermined temperature.

[0003] Patent Document 1 below proposes a method for producing cooked rice that enables sterilization for long-term storage without prolonging the production process. Patent Document 2 below also proposes a technique for producing cooked rice that enables sterilization for storage for a certain period of time with an improved texture without prolonging the production process. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6667767 [Patent Document 2] Patent No. 6678950 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the production methods described in Patent Documents 1 and 2, cooked rice that can be stored for long periods in an edible state can be produced without the need for water or a heating device, but it is desirable to be able to more reliably and stably produce cooked rice that can be stored for long periods at room temperature.

[0006] The present invention has been made in consideration of the above circumstances, and aims to make it possible to more reliably and stably produce cooked rice that can be stored at room temperature for long periods of time. [Means for solving the problem]

[0007] A method for producing cooked rice according to one aspect of the present invention includes a soaking step of soaking unwashed rice made from non-glutinous rice or glutinous rice in water for at least 120 minutes, soaking the rice in water in an amount that is 30 to 33% by weight of the weight of the rice before soaking; a rice cooking step of adding water that is 90 to 100% by weight of the rice that has been soaked to the rice that has been soaked, and cooking the rice; a first cooling step of cooling the cooked rice until the central temperature of the cooked rice is 40 to 50°C; and (i) adding a soybean-derived β-amylase enzyme preparation as an enzyme preparation in an amount of 1.0 to 1.8% by weight of the cooked rice based on the weight of the cooked rice and stirring the β-amylase enzyme preparation evenly to the cooked rice that has been cooled and is at 40 to 50°C based on the weight of the cooked rice, or (ii) adding a microbial-derived β-amylase enzyme preparation as an enzyme preparation in an amount of 1.6 to 2.2% by weight of the cooked rice based on the weight of the cooked rice and stirring the β-amylase enzyme preparation evenly to the cooked rice. a second cooling step of cooling the cooked rice after the stirring step to 20°C or below within 20 to 30 minutes from the end of the stirring step; a sterilization step of placing the cooked rice after the stirring step into a pasteurization chamber and (iii) storing it at an internal temperature of 60 to 70°C for 9 to 13 hours if the cooking rice has undergone the stirring step (i), or (iv) storing it at an internal temperature of 53 to 60°C for 11 to 14 hours if the cooking rice has undergone the stirring step (ii); a packaging step of sealing and packaging the cooked rice after the sterilization step; and a sterilization step of (v) storing the cooked rice after the packaging step for 10 to 15 minutes while maintaining the central temperature of the cooked rice at 100 to 110°C if the cooking rice has undergone the sterilization step (iii), or (vi) storing it for 10 to 30 minutes while maintaining the central temperature of the cooked rice at 90 to 100°C if the cooking rice has undergone the sterilization step (iv). [Effects of the Invention]

[0008] According to the present invention, it is possible to more reliably and stably produce cooked rice that can be stored at room temperature for long periods of time. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of a production line used in a method for producing cooked rice according to the present invention. [Figure 2] 1 is a flowchart showing a first embodiment of a method for producing cooked rice according to the present invention. [Figure 3] FIG. 10 is a diagram showing an example of cooked rice packaged in a heat-resistant film after molding. [Figure 4] This is a perspective view showing how formed cooked rice wrapped in a heat-resistant film is placed into a barrier nylon poly three-sided seal bag. [Figure 5] 10 is a flowchart showing a method for producing allergy-free cooked rice that can be stored for a short period of time according to a second embodiment of the present invention. [Figure 6] 10 is a flowchart showing a method for producing short-term storable cooked rice according to a third embodiment of the present invention. [Figure 7] 10 is a flowchart showing a method for producing long-term storable cooked rice according to a fourth embodiment of the present invention. [Figure 8] 10 is a flowchart showing a method for producing allergy-free cooked rice that can be stored for a long period of time according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes a method for producing cooked rice according to an embodiment of the present invention. Cooked rice here includes both non-glutinous rice and glutinous rice. The long-term storage period for cooked rice is divided into two periods, and each period is explained below. A storage period of approximately three months is defined as "medium-term," while a storage period of more than three months and up to five years is defined as "long-term." In other words, "long-term storage" includes both "medium-term" and "long-term." Furthermore, both cases of using "soybean-derived β-amylase" and "microbial-derived β-amylase" that are allergy-free are explained below as enzymes required for producing cooked rice to be stored for medium and long periods.

[0011] Fig. 1 is a diagram showing an example of a production line used in a method for producing cooked rice according to the present invention, Fig. 2 is a flowchart showing a first embodiment of a method for producing cooked rice according to the present invention.

[0012] <Soaking process: S1> Wash the rice, place it in a soaking tank, and add water. Soak the rice in water for at least 120 minutes, so that the rice is soaked in water that is 30 to 33% by weight of the weight of the rice before soaking.

[0013] <Rice cooking process: S2> The rice that has undergone the soaking process is placed in a rice cooker, and water equivalent to 90 to 99% of the weight of the rice that has undergone the soaking process is added, followed by cooking. This cooking method may be any ordinary rice cooking method.

[0014] <First cooling process: S3> After the rice cooking process, the cooked rice, which has reached a temperature of 90°C or higher, is cooled until the core temperature of the cooked rice reaches 40 to 50°C. For the next process, the cooked rice is divided into separate containers, for example, in 10 kg portions.

[0015] <Stirring process: S4> (i) After the first cooling step, the cooked rice is cooled to a core temperature of 40-50°C. A soybean-derived β-amylase enzyme preparation is sprinkled evenly over the cooked rice, and added at a weight ratio of 1.0-1.8% based on the weight of the cooked rice. The mixture is then stirred until the β-amylase preparation is evenly mixed into the cooked rice. This stirring is preferably performed using a rice mixer for approximately 1 minute (e.g., 45-80 seconds) per 10 kg of cooked rice. The soybean-derived β-amylase preparation has a relative activity of 100% and an optimum temperature of 60-70°C. The soybean-derived β-amylase preparation has an activation temperature of 100°C or higher. For example, a soybean-derived β-amylase preparation containing 12.5% ​​soybean-derived β-amylase, 8.0% glycerin fatty acid ester, 5.0% sodium metaphosphate, and 74.5% food ingredients is used. As a commercially available product, for example, Mochi Soft MF (registered trademark) by OYC Foods Net Co., Ltd. is used.

[0016] Alternatively, (ii) after the first cooling step, a microbial β-amylase enzyme preparation is evenly sprinkled over cooked rice whose core temperature is 40-50°C. The β-amylase preparation is added at 1.6-2.2% by weight based on the weight of the cooked rice, and the mixture is stirred until the β-amylase preparation is evenly mixed into the cooked rice. This stirring is preferably performed using a rice mixer for approximately 1 minute (e.g., 45-80 seconds) per 10 kg of cooked rice. The microbial β-amylase preparation has a relative activity of 100% and an optimum temperature of 53-60°C. The microbial β-amylase preparation also has an activation temperature of 90°C or higher. For example, an enzyme preparation containing 9.00% microbial β-amylase and 91.00% food ingredients is used as the microbial β-amylase enzyme preparation. An example of a commercially available product is Neo Mochi Soft from OYC Foods Net Co., Ltd. Microbial β-amylase is allergy-free.

[0017] In the stirring step, a β-amylase enzyme preparation is used as the enzyme preparation. β-amylase is a type of amylase and is characterized by being an inverting hydrolase that hydrolyzes the α-1.4 gluconate bonds of starch from the non-reducing end to the exo-form, producing β-anomer maltose (malt sugar). Taking advantage of this enzyme's properties, the β-amylase enzyme preparation is added to cooked rice that has undergone the first cooling step at the timing, amount, and cooked rice temperature shown in this embodiment.

[0018] <Second cooling process: S5> After the stirring step (i) or (ii) above is completed, the cooked rice is cooled to 20°C or below within 20 to 30 minutes from the end of the stirring step. For example, a vacuum cooler is used for this cooling. In the method for producing cooked rice according to this embodiment, the second cooling step is performed at this timing, thereby improving the production stability of cooked rice that can be stored for a long period of time.

[0019] <Ingredient addition process: S6> The cooked rice (enzyme-added) cooled in the second cooling step is placed in a rice mixer (e.g., Fuji Seiki Co., Ltd.), and the ingredients listed below are added on top and stirred until the ingredients are evenly mixed with the cooked rice. The stirring time is, for example, about 1 to 2 minutes per 10 kg of cooked rice.

[0020] (Examples of ingredients to add) For perilla rice balls: 2% perilla powder (200g) per 10kg of cooked rice For salted rice balls: 1% (100g) per 10kg of cooked rice Gomoku rice ball: 15% (1500g) of cooked gomoku rice for 10kg of cooked rice. The ingredients of the gomoku rice are shiitake mushroom, burdock, carrot, fried tofu, and konjac. Kelp rice balls: 10% (1kg) of kelp tsukudani to 10kg of cooked rice Shiso plum rice ball: For 10 kg of cooked rice, add 1.0% (100 g) shiso powder and 4% (400 g) crunchy plums. When producing cooked rice without adding ingredients, the step of adding ingredients is not carried out.

[0021] <Molding process: S7> After the second cooling step or the ingredient addition step, the cooked rice is further loosened manually or mechanically (for example, a lift with a hoist by Fuji Seiki Co., Ltd.) and then placed in a molding machine (for example, a small molder II3300 model GKT-3300 by Fuji Seiki Co., Ltd.). Then, as shown in FIG. 3, the formed cooked rice 10 is packaged in a heat-resistant film 3. This packaging can be done manually, but for example, an automatic packaging machine is used. The heat-resistant film 3 is made of, for example, polyethylene (PE) or polypropylene (PP).

[0022] <Sterilization process: S8> After the shaping process, the cooked rice is placed in a low-temperature sterilization cabinet and stored there. (iii) In the case of cooked rice to which an enzyme preparation has been added and stirred in the stirring step as described above in (i), the cooked rice is placed in a low-temperature sterilization cabinet and stored at an internal temperature of 60 to 70°C for 9 to 13 hours. (iv) In the case of cooked rice to which an enzyme preparation has been added and stirred in the stirring step as described in (ii) above, the cooked rice is placed in a pasteurization cabinet and stored at an internal temperature of 53 to 60°C for 11 to 14 hours.

[0023] This sterilization process completely kills pathogenic microorganisms such as tuberculosis and Bacillus cereus, which are highly heat-resistant, thereby minimizing deterioration of the flavor, color, and nutritional value of cooked rice.

[0024] Furthermore, the sterilization process promotes the activation of the enzyme preparation, thereby decomposing the α-starch contained in cooked rice. When rice is cooked, the β-starch contained in the rice is converted to α-starch. The conversion of β-starch to α-starch improves the taste of cooked rice and makes it easier to digest. However, as time passes after cooking, the α-starch reverts to β-starch. Therefore, the α-starch is decomposed using the enzyme preparation described above as a starch-degrading enzyme.

[0025] For example, when β-amylase is used as a starch-degrading enzyme, the α-1,4 bond of amylopectin, which constitutes α-starch, is degraded. However, the α-1,6 bond of amylopectin is not degraded. Therefore, α-starch is degraded mainly into dextrin (limit dextrin) and maltose. This makes it possible to prevent the degradation of α-starch from impairing taste. Furthermore, because β-amylase degrades only the terminal branching portions of amylopectin, it is possible to suppress the conversion of α-starch to β-starch.

[0026] <Packaging process: S9> The cooked rice packaged in the heat-resistant film during the molding process is further packaged in, for example, a barrier nylon poly three-sided seal bag or a four-layer aluminum film (retort pouch). Figure 4 shows an example of cooked rice 10 packaged in a heat-resistant film 3 packaged in a barrier nylon poly three-sided seal bag 8. During packaging, cooked rice that has undergone the sterilization process and an oxygen absorber are placed in the barrier nylon poly three-sided seal bag or the four-layer aluminum film package, and after degassing, the package is heat-sealed. For example, an automatic packaging machine (e.g., TVP-E3 / E4, manufactured by Toyo Jidosha Co., Ltd.) is used for this packaging. For example, when making products such as rice balls, a paper pole, plastic, or the like can be enclosed in the package to prevent crushing.

[0027] <Sterilization process: S10> (v) In the case of cooked rice that has undergone the above-mentioned (i) in the stirring step, (iii) in the sterilization step, and then undergone the packaging step, the cooked rice is kept at a predetermined temperature range of 100-110°C or higher, and the central temperature of the cooked rice is maintained at 100°C or higher for 10-15 minutes. Alternatively, in the case of cooked rice that has undergone the above-mentioned (vi) in the stirring step, (ii) in the sterilization step, (iv) in the sterilization step, and then undergone the packaging step, the cooked rice that has undergone the packaging step is stored for 10-30 minutes with the central temperature of the cooked rice maintained at 90-100°C. This also kills the enzymes added in the stirring step. For example, a hot water jet cooking sterilizer model SGC by Samsung Corporation is used for this sterilization step.

[0028] As described above, by carrying out steps S1 to S10, cooked rice that can be stored for at least a medium period or longer can be obtained, and the reliability of long-term storage can be further increased without significantly extending the production process beyond 24 hours.

[0029] Next, a method for producing medium-term storable, allergy-free cooked rice according to a second embodiment of the present invention will be described. Fig. 5 is a flowchart showing a method for producing medium-term storable, allergy-free cooked rice according to the second embodiment of the present invention.

[0030] The method for producing medium-term storable, allergy-free cooked rice according to the second embodiment of the present invention includes the following steps.

[0031] In the second embodiment, first, the soaking step (S1), the rice cooking step (S2), and the first cooling step (S3) are performed in the same manner as in the first embodiment.

[0032] <Stirring process: S4> Next, a stirring step is carried out. In the stirring step, according to the conditions in (ii) above, a microbial β-amylase enzyme preparation is evenly sprinkled over the cooked rice whose core temperature has reached 40 to 50°C after the first cooling step, and added in an amount of 1.6 to 2.2% by weight based on the weight of the cooked rice, and the mixture is stirred until the β-amylase enzyme preparation is evenly mixed into the cooked rice.

[0033] Next, the second cooling step (S5), the ingredient addition step (S6), and the shaping step (S7) are performed in the same manner as in the first embodiment. However, in the ingredient addition step (S6), ingredients that may cause allergies are not used. In the above example, only ingredients for the perilla rice ball, salt rice ball, or perilla and plum rice ball are used. Note that when producing rice without ingredients, the ingredient addition step (S6) is not performed.

[0034] <Sterilization process: S8> Next, a sterilization step is carried out. In the sterilization step, the cooked rice that has been packaged is placed in a low-temperature sterilization chamber under the conditions (iv) above, and stored at a chamber temperature of 53 to 60°C for 11 to 14 hours.

[0035] <Packaging process: S9> Next, the packaging process is carried out. In the packaging process, the cooked rice that has undergone the sterilization process is packaged in a barrier nylon poly three-sided seal bag. In other words, the cooked rice that has been packaged in a heat-resistant film in the molding process is further packaged in a barrier nylon poly three-sided seal bag. When packaging, the cooked rice that has undergone the sterilization process and an oxygen absorber are placed in the package.

[0036] <Sterilization process: S10> Next, a sterilization step is carried out. In the sterilization step, the cooked rice that has been packaged is stored for 10 to 30 minutes while maintaining the core temperature of the cooked rice at 90 to 100°C in accordance with the conditions in (vi) above.

[0037] As described above, by carrying out steps S1 to S10, it is possible to obtain allergy-free cooked rice that can be stored for a medium period of at least about three months, and the reliability of long-term storage can be further increased without significantly extending the manufacturing process as described above.

[0038] Next, a method for producing medium-term storable cooked rice according to a third embodiment of the present invention will be described. Fig. 6 is a flowchart showing a method for producing short-term storable cooked rice according to the third embodiment of the present invention.

[0039] The method for producing medium-term storable cooked rice according to the third embodiment of the present invention includes the following steps.

[0040] In the third embodiment, first, the soaking step (S1), the rice cooking step (S2), and the first cooling step (S3) are performed in the same manner as in the first embodiment.

[0041] <Stirring process: S4> Next, a stirring step is carried out. In the stirring step, a soybean-derived β-amylase enzyme preparation is evenly sprinkled over the cooked rice in an amount of 1.0 to 1.8% by weight based on the weight of the cooked rice, according to the conditions in (i) above, and stirred until the β-amylase enzyme preparation is evenly mixed with the cooked rice.

[0042] Subsequently, the second cooling step (S5), the ingredient adding step (S6), and the shaping step (S7) are carried out in the same manner as in the first embodiment.

[0043] <Sterilization process: S8> Next, a sterilization step is carried out. In the sterilization step, the cooked rice is placed in a low-temperature sterilization chamber and stored at a temperature of 60 to 70°C for 9 to 13 hours according to the conditions in (iii) above.

[0044] <Packaging process: S9> Next comes the packaging process. In the packaging process, the cooked rice that has undergone the sterilization process is packaged in a barrier nylon poly three-sided seal bag. When packaging, the cooked rice that has undergone the sterilization process and an oxygen absorber are placed into the package.

[0045] <Sterilization process: S10> Next, a sterilization process is carried out. In the sterilization process, the cooked rice is stored for 10 to 15 minutes while the core temperature is maintained at 100 to 110°C according to the conditions in (v) above.

[0046] By carrying out steps S1 to S10 as described above, cooked rice that can be stored for a medium period of at least three months can be obtained, and the reliability of long-term storage can be further increased without significantly extending the manufacturing process as described above.

[0047] Next, a method for producing long-term storable cooked rice according to a fourth embodiment of the present invention will be described. Fig. 7 is a flowchart showing the method for producing long-term storable cooked rice according to the fourth embodiment of the present invention.

[0048] The method for producing cooked rice that can be stored for a long period of time according to the fourth embodiment of the present invention includes the steps shown below.

[0049] In the fourth embodiment, first, the soaking step (S1), the rice cooking step (S2), and the first cooling step (S3) are performed in the same manner as in the first embodiment.

[0050] <Stirring process: S4> Next, a stirring step is carried out. In the stirring step, a soybean-derived β-amylase enzyme preparation is evenly sprinkled over the cooked rice in an amount of 1.0 to 1.8% by weight based on the weight of the cooked rice, according to the conditions in (i) above, and stirred until the β-amylase enzyme preparation is evenly mixed with the cooked rice.

[0051] Subsequently, the second cooling step (S5), the ingredient adding step (S6), and the shaping step (S7) are carried out in the same manner as in the first embodiment.

[0052] <Sterilization process: S8> Next, a sterilization step is carried out. In the sterilization step, the cooked rice is placed in a low-temperature sterilization chamber and stored at a temperature of 60 to 70°C for 9 to 13 hours according to the conditions in (iii) above.

[0053] <Packaging process: S9> Next comes the packaging process, where the cooked rice that has undergone the sterilization process is packaged in a four-layer aluminum film (retort pouch). When packaging, the cooked rice that has undergone the sterilization process and an oxygen absorber are placed into the package.

[0054] <Sterilization process: S10> Next, a sterilization step is carried out. In the sterilization step, the cooked rice that has been packaged is placed in a retort kettle and sterilized. In the sterilization step in the fourth embodiment, instead of the conditions (v) and (vi) above, the cooked rice that has been packaged is placed in a retort kettle and sterilized for 22 to 27 minutes at a central temperature of 115 to 125°C. As a retort food, cooked rice is optimally sterilized to have an F value of 4 or more.

[0055] By carrying out steps S1 to S10 as described above, cooked rice that can be stored for a long period of time can be obtained, and the reliability of long-term storage can be further increased without significantly lengthening the production process.

[0056] Next, a method for producing allergy-free cooked rice that can be stored for a long period of time according to a fifth embodiment of the present invention will be described. Fig. 8 is a flowchart showing a method for producing allergy-free cooked rice that can be stored for a long period of time according to the fifth embodiment of the present invention.

[0057] The method for producing allergy-free cooked rice that can be stored for a long period of time according to the fifth embodiment of the present invention includes the steps shown below.

[0058] In the fifth embodiment, first, the soaking step (S1), the rice cooking step (S2), and the first cooling step (S3) are performed in the same manner as in the first embodiment.

[0059] <Stirring process: S4> Next, a stirring step is carried out. In the stirring step, according to the conditions in (ii) above, a microbial β-amylase enzyme preparation is evenly sprinkled over the cooked rice whose core temperature has reached 40 to 50°C after the first cooling step, and added in an amount of 1.6 to 2.2% by weight based on the weight of the cooked rice, and the mixture is stirred until the β-amylase enzyme preparation is evenly mixed into the cooked rice.

[0060] Next, the second cooling step (S5), the ingredient addition step (S6), and the shaping step (S7) are performed in the same manner as in the first embodiment. However, in the ingredient addition step (S6), ingredients that may cause allergies are not used. In the above example, only ingredients for the perilla rice ball, salt rice ball, or perilla and plum rice ball are used. Note that when producing rice without ingredients, the ingredient addition step (S6) is not performed.

[0061] <Sterilization process: S8> Next, a sterilization step is carried out. In the sterilization step, the cooked rice that has been packaged is placed in a low-temperature sterilization chamber under the conditions (iv) above, and stored at a chamber temperature of 53 to 60°C for 11 to 14 hours.

[0062] <Packaging process: S9> After the sterilization process, the cooked rice is packaged in a four-layer aluminum film (retort pouch). When packaging, the cooked rice and oxygen absorber are placed inside the package.

[0063] <Sterilization process: S10> Next, a sterilization process is carried out. In the sterilization process, the cooked rice that has been packaged is placed in a retort pouch and sterilized. In the sterilization process in the fifth embodiment, instead of the conditions (v) and (vi) above, the cooked rice that has been packaged is stored for 8 to 12 minutes while the core temperature of the cooked rice is maintained at 107 to 113°C.

[0064] By carrying out steps S1 to S10 as described above, it is possible to obtain allergy-free cooked rice that can be stored for a long period of time, and the reliability of long-term storage can be further increased without significantly extending the manufacturing process as described above.

[0065] In this embodiment, the rice used may be any of Japonica rice, Indica rice, and Japanica rice, or even glutinous rice. The rice may be polished to any degree, such as brown rice, 30% polished rice, 50% polished rice, or 70% polished rice.

[0066] The present invention is not limited to the configuration of the above embodiment, and various modifications are possible. In the above embodiment, the configuration and processing shown in the above embodiment using Figures 1 to 8 are merely one embodiment of the present invention, and are not intended to limit the present invention to these configurations and processing. [Explanation of symbols]

[0067] 10 Rice 3. Heat-resistant film 8 Barrier nylon poly three-side seal bags

Claims

1. a soaking step in which unwashed rice made of non-glutinous rice or glutinous rice is soaked in water for at least 120 minutes to soak the rice in water in an amount of 30 to 33% by weight based on the weight of the rice before soaking; a rice cooking process in which the rice that has been soaked is cooked by adding water having a weight of 90 to 100% of the weight of the rice that has been soaked; A first cooling step of cooling the cooked rice after the rice cooking step until the central temperature of the cooked rice reaches 40 to 50 ° C.; After the cooling process, the cooked rice is cooled to 40 to 50 ° C. (i) Adding a soybean-derived β-amylase enzyme preparation as an enzyme preparation in an amount of 1.0 to 1.8% by weight based on the weight of cooked rice, and stirring the β-amylase enzyme preparation to mix evenly with the cooked rice; or (ii) adding a microbial beta-amylase enzyme preparation as an enzyme preparation in an amount of 1.6 to 2.2% by weight relative to the weight of cooked rice, and stirring the beta-amylase enzyme preparation to mix evenly with the cooked rice; A second cooling step in which the cooked rice after the stirring step is cooled to 20 ° C. or less within 20 to 30 minutes from the time when the stirring step is completed; After the stirring process, the cooked rice is placed in a pasteurizer. (iii) If the stirring step (i) has been carried out, the mixture is stored at a temperature of 60 to 70°C for 9 to 13 hours, Or (iv) if the stirring step (ii) has been carried out, a sterilization step of storing the mixture at a temperature of 53 to 60 ° C. for 11 to 14 hours; A packaging process in which the cooked rice that has undergone the sterilization process is sealed and packaged; The cooked rice that has undergone the packaging process is (v) After the sterilization step (iii), the cooked rice is stored for 10 to 15 minutes while maintaining the core temperature at 100 to 110°C. Or (vi) if the sterilization step (iv) has been carried out, a sterilization step of storing the cooked rice for 10 to 30 minutes while maintaining the central temperature of the cooked rice at 90 to 100 ° C. A method for producing cooked rice comprising the steps of:

2. In the stirring step, the β-amylase derived from a microorganism is added to the cooked rice that has been subjected to the first cooling step in an amount of 1.6 to 2.2% by weight relative to the weight of the cooked rice under the condition (ii), and the mixture is stirred; In the sterilization step, under the conditions of (iv), the cooked rice that has been subjected to the second cooling step is placed in a pasteurization chamber and stored at an internal temperature of 53 to 60°C for 11 to 14 hours, In the packaging step, the cooked rice that has undergone the sterilization step is packaged using a barrier nylon poly three-sided seal bag, 2. The method for producing cooked rice according to claim 1, wherein in the sterilization step, the cooked rice after the packaging step is kept at 90 to 100 ° C. under the condition (vi) and stored for 10 to 30 minutes.

3. In the stirring step, soybean-derived β-amylase is added to the cooked rice that has been subjected to the first cooling step in an amount of 1.0 to 1.8% by weight relative to the weight of the cooked rice, and the mixture is stirred under the condition (i), In the sterilization step, under the conditions of (iii), the cooked rice that has been subjected to the second cooling step is placed in a pasteurization chamber and stored at an internal temperature of 60 to 70°C for 9 to 13 hours, In the packaging step, the cooked rice that has undergone the sterilization step is packaged using a barrier nylon poly three-sided seal bag, 2. The method for producing cooked rice according to claim 1, wherein in the sterilization step, the cooked rice after the packaging step is kept at 100 to 110 ° C. under the condition (v) and stored for 10 to 15 minutes.

4. In the stirring step, soybean-derived β-amylase is added to the cooked rice that has been subjected to the first cooling step in an amount of 1.0 to 1.8% by weight relative to the weight of the cooked rice, and the mixture is stirred under the condition (i), In the packaging step, the cooked rice that has undergone the sterilization step is packaged using a four-layer aluminum film. In the sterilization step, under the conditions of (iii), the cooked rice that has been packaged is placed in a pasteurization chamber and stored at a chamber temperature of 60 to 70°C for 9 to 13 hours, In the sterilization step, instead of the condition (v), the cooked rice after the packaging step is placed in a retort kettle and stored for 22 to 27 minutes at a central temperature of 115 to 125 ° C. The method for producing cooked rice according to claim 1.

5. In the stirring step, the β-amylase derived from a microorganism is added to the cooked rice that has been subjected to the first cooling step in an amount of 1.6 to 2.2% by weight relative to the weight of the cooked rice under the condition (ii), and the mixture is stirred; In the sterilization step, under the conditions of (iv), the cooked rice that has been subjected to the second cooling step is placed in a pasteurization chamber and stored at an internal temperature of 53 to 60°C for 11 to 14 hours, In the packaging step, the cooked rice that has undergone the sterilization step is packaged using a four-layer aluminum film.

2. The method for producing cooked rice according to claim 1, wherein, in the sterilization step, instead of the condition (vi), the cooked rice after the packaging step is kept at a temperature of 107 to 113 ° C. and stored for 8 to 12 minutes.

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