Method for producing packaged cooked rice

Abstract

To provide a method for producing packaged cooked rice easily eatable without heating and giving satisfaction as staple food.SOLUTION: The method comprises the steps of: charging raw brown rice into a packaging container; adding raw water into the packaging container; hermetically sealing the raw brown rice and the raw water in the packaging container; and cooking the raw brown rice hermetically sealed in the packaging container, wherein the raw brown rice is giant germ-containing brown rice, and the raw water is added in an amount of about 300% by weight of the raw brown rice charged into the packaging container.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Packaged cooked rice, also known as packed rice, is a food product in which cooked rice is sealed in an airtight container under sterile conditions. Currently available on the market as packaged cooked rice is sterilized packaged cooked rice that is cooked and packaged in a sterile room, and retort rice that is pressurized and heated (cooked and sterilized) after packaging. These products can be stored for long periods at room temperature, and because the cooked rice is sealed inside, they are highly convenient and can be eaten simply by heating them for a short time in a microwave oven or the like. Known techniques for producing such packaged cooked rice include those described in Patent Documents 1 and 2 below. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-226087 [Patent Document 2] Patent Publication No. 2021-27816 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional packaged cooked rice typically has a moisture content of 60% to 65%. When stored at room temperature after production, the starch contained in the cooked rice undergoes beta conversion (aging), resulting in a deterioration in flavor. Therefore, before eating, the cooked rice must be heated to undergo gelatinization (gelatinization), making it unsuitable for consumption as is. On the other hand, retort pouched rice porridge (porridge in a retort pouch), which is produced by filling and sealing rice and fresh water in a heat-resistant container, has a moisture content of 83% or more, making it difficult for the cooked rice to undergo beta conversion and allowing it to be eaten without heating. However, due to the softness of the rice grains, the resulting porridge lacks a grainy texture, making it difficult to provide a satisfying staple food. However, in recent years, with the increasing need for emergency food in the event of a disaster and the growing demand for fast food among busy modern people, there has been a demand for packaged cooked rice that can be easily eaten without heating and still provide a satisfying staple food.

[0005] Therefore, an object of the present invention is to provide a method for producing packaged cooked rice that can be easily eaten without heating and provides a satisfying feeling as a staple food, by solving such problems. [Means for solving the problem]

[0006] In order to achieve the above object, the first invention is: A method for producing packaged cooked rice, comprising: a pouring step of pouring raw material brown rice into a packaging container; a hydration step of adding raw material water into the packaging container; a sealing step of hermetically sealing the raw material brown rice and raw material water in the packaging container; and a cooking step of cooking the raw material brown rice hermetically sealed in the packaging container, The raw brown rice is made of giant germ rice, The present invention provides a method for producing packaged cooked rice, characterized in that in the water addition step, raw material water is added in an amount of approximately 300% by weight of the raw material brown rice placed in the packaging container.

[0007] According to the first invention, it is possible to provide a method for producing packaged cooked rice that can be easily eaten without heating and that can provide a sense of satisfaction as a staple food.

[0008] The second invention has the same configuration as the first invention, but also: Furthermore, a heated steam injection step is provided in which the raw material brown rice is subjected to a heat treatment with steam before the adding step, The heated steam injection process is characterized by comprising a step of injecting pressurized heated steam onto the raw brown rice for several seconds, and a step of drying the raw brown rice with hot air after the pressurized heated steam injection.

[0009] According to the second invention, in addition to the effects of the first invention, This produces changes in the waxy layer that covers the surface of the raw brown rice, which has the effect of promoting water absorption in later processes.In addition to the sterilizing effect, this produces changes in the waxy layer that covers the surface of the raw brown rice, which in turn promotes water absorption (makes it easier to absorb water) in later processes, making it possible to simplify or omit the rice washing and soaking processes during cooking.This allows the surface of the grains to maintain an appropriate hardness after cooking, so the grain texture after cooking (i.e., the satisfaction when eating) can be maintained well.

[0010] The third invention, in addition to the configuration of the second invention, The raw material brown rice is characterized in that it is low-amylose rice.

[0011] According to the third aspect of the present invention, in addition to the effects of the second aspect of the present invention, Since the aging of cooked rice can be prevented more effectively, it becomes possible to maintain the cooked rice in a state suitable for eating for a longer period of time after cooking.

[0012] The fourth invention, in addition to the configuration of the third invention, The raw material brown rice is characterized in that the sugar alcohol content is 14 mg or more per 100 g of grain weight.

[0013] The fourth invention, in addition to the configuration of the third invention, By using raw rice with a high sugar alcohol content, staling of cooked rice can be prevented more effectively, and the cooked rice can be kept in a state suitable for eating for an even longer period after cooking. [Effects of the Invention]

[0014] According to the present invention, a method for producing packaged cooked rice can be provided that can be easily eaten without heating and that can provide a satisfying feeling as a staple food. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is an enlarged comparative view of an example of giant germ rice brown rice and regular brown rice used in a method for producing packaged cooked rice according to an embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart showing the manufacturing process of packaged cooked rice according to an embodiment of the present invention. [Figure 3] FIG. 3 is a comparative photograph of packaged rice produced by a method for producing packaged rice according to an embodiment of the present invention and ordinary packaged rice (retort rice). In detail, FIG. 3(a) is a comparative photograph showing the appearance when chopsticks are inserted into the rice portion of each packaged rice in an unheated state, and FIG. 3(b) is a comparative photograph showing the appearance when the rice is stirred with chopsticks. DETAILED DESCRIPTION OF THE INVENTION

[0016] <1. About the raw rice used in packaged cooked rice> A method for manufacturing packaged cooked rice according to an embodiment of the present invention will be described below with reference to the drawings. First, the raw material rice used in the method for manufacturing packaged cooked rice according to an embodiment of the present invention will be described. The raw material rice used in the method for manufacturing packaged cooked rice according to an embodiment of the present invention is brown rice of giant germ rice. Here, in this specification, brown rice refers to seeds obtained by threshing harvested rice ears and removing the husk. Furthermore, giant germ rice refers to rice with approximately three times the germ weight compared to regular rice. For example, regular brown rice has 5-6% bran, 2-3% germ, and 92% endosperm, but giant germ rice is rice with approximately 6-12% germ in the brown rice, which is approximately three times the proportion of germ compared to regular brown rice. More specifically, it is common knowledge in the rice industry that the germ weight of regular brown rice (0.02g / grain) is about 3% (approximately 0.0006g) per grain, but if the germ weight is at least 9% (approximately 0.0018g) or more of the grain weight, it can be said to be giant germ brown rice. However, the germ weight does not strictly have to be 9% or more of the grain weight; for example, a deviation of about -1 to 2% is acceptable. Specific examples of giant germ rice varieties include "Kin no Ibuki (variety registration number 24378)" (approximately 7-9% germ in brown rice), "Haigokoro (variety registration number 23276)" (approximately 9.2% germ in brown rice), "Kamiakari (variety registration number 16284)" and "Haiminori (variety registration number 8008)" (approximately 11.1% germ in brown rice).

[0017] Furthermore, while there are no particular limitations on the rice variety used for the giant germ rice according to the present invention, Kin no Ibuki is preferred. FIG. 1 is an enlarged comparative diagram of an example of giant germ rice brown rice br1 and regular brown rice br2 used in the manufacturing method for packaged cooked rice according to an embodiment of the present invention. More specifically, the grain br1 in the diagram is a schematic representation of an enlarged grain of giant germ rice brown rice (variety: Kin no Ibuki) used in the manufacturing method for packaged cooked rice according to the embodiment, and the grain br2 is a schematic representation of an enlarged grain of commercially available regular brown rice (variety: Koshihikari). Furthermore, the areas a1 and a2 enclosed by dashed lines in the diagram correspond to the germ. As shown in the diagram, there is a significant difference in the size of the germ portion between the giant germ rice brown rice br1 and the regular brown rice br2, even in appearance. The surface area of ​​the germ portion a1 of the giant germ rice brown rice br1 is typically approximately three times larger than the surface area of ​​the germ portion a2 of the regular brown rice br2.

[0018] In the manufacturing method of packaged cooked rice according to an embodiment of the present invention, the grains are cooked in brown rice form in the manufacturing process described below, which makes it easier to maintain the graininess of cooked rice for a long period of time even at high moisture content after cooking. Here, the surface of brown rice is covered with a waxy layer, so it generally does not absorb water easily during soaking. The only part that absorbs water is the germ, but the germ of ordinary brown rice is small, so it takes time to absorb water. This requires a long soaking time to allow the grains to absorb enough moisture for cooking, and the endosperm cannot absorb enough water. As a result, the grains tend to harden after cooking, and the low moisture content can easily cause starch aging, resulting in a loss of texture in the cooked rice. To address this issue, one method is to process the surface of the brown rice, such as by making cuts, to facilitate water absorption in order to allow the endosperm to absorb enough water. However, this damage to the grain surface can lead to a loss of graininess after cooking and a tendency for starch aging.

[0019] In contrast, the method for producing packaged cooked rice according to an embodiment of the present invention further uses large-germ brown rice as the raw material rice. Because the germ portion, which serves as the water absorption port, is larger than that of regular brown rice, the endosperm portion can absorb sufficient water before cooking, compared to regular brown rice. Therefore, there is no need to make cuts or other processing on the surface of the brown rice to facilitate water absorption before cooking (in other words, without damaging the surface of the grain), and the endosperm portion can absorb sufficient water, resulting in grains with an appropriate hardness suitable for eating after cooking. Furthermore, by allowing the germ portion to absorb water and allowing the endosperm portion to absorb sufficient moisture, moisture loss from the grains is reduced even after cooking, and starch aging can be prevented for a long period of time. As a result, packaged cooked rice can be produced that can be easily eaten without heating, retains a good grain texture for a long period of time after cooking, and provides a satisfying staple food.

[0020] Furthermore, it is preferable that low-amylose rice be used as the raw material rice in the manufacturing method for packaged cooked rice according to an embodiment of the present invention. This is because the use of low-amylose rice can reduce the beta-conversion (aging) of starch contained in the cooked rice. Here, low-amylose rice generally refers to rice with an amylose content of less than 12% by mass, and known varieties include Milky Queen, Milky Summer, Milky Pearl, Yumepirika, Snow Pearl, Nebari Kachi, and Kin no Ibuki. The use of low-amylose rice can more effectively prevent cooked rice from aging, allowing it to remain in a state suitable for eating for a longer period after cooking.

[0021] Furthermore, the higher the sugar alcohol (sorbitol, which is believed to have an effect on inhibiting aging) content of the raw material rice used in the manufacturing method for packaged cooked rice according to an embodiment of the present invention, the more preferable it is from the perspective of preventing aging. Specifically, it is preferable for the sugar alcohol content to be 14 mg or more per 100 g of grain weight. For example, the Nanatsuboshi variety typically contains 1.4 mg of sugar alcohol per 100 g of grain weight, and the Kin no Ibuki variety typically contains 14.4 mg of sugar alcohol per 100 g of grain weight. The use of raw material rice with a high sugar alcohol content can more effectively prevent aging of the cooked rice, making it possible to maintain the rice in a state suitable for eating for an even longer period after cooking.

[0022] <2. Manufacturing process of packaged cooked rice> FIG. 2 is a flowchart showing the manufacturing process of packaged cooked rice according to an embodiment of the present invention. As shown in Figure 2, the manufacturing process for packaged cooked rice according to an embodiment of the present invention consists of, from upstream to downstream, a heated steam injection process (step #1), a pouring process (step #2), a hydration process (step #3), a sealing process (step #4), a rice cooking process (step #5), a cooling process (step #6), and a container drying process (step #7). Each process will be explained below.

[0023] The heated steam injection process (step #1), also known as the steam cleaning process, is a process in which raw material brown rice (i.e., unprocessed brown rice used as a raw material) is subjected to a heat treatment using steam. Specifically, a predetermined amount of raw material brown rice is placed in a steam sterilizer (not shown), and the brown rice placed in the steam sterilizer is sent into an enclosed space within the steam sterilizer. Within this enclosed space, pressurized heated steam (e.g., 70 atmospheres, 250°C) is injected onto the entire raw material brown rice for several seconds (approximately 5 seconds). At this time, the surface moisture of the raw material brown rice is reduced to approximately 18%. Subsequently, the steam sterilizer uses warm air drying (approximately 40°C) to dry the raw material brown rice after the pressurized heated steam injection down to approximately 14% surface moisture. The heated steam injection process described above not only has a sterilizing effect, but also changes the waxy layer that covers the surface of the raw brown rice, which in turn promotes the raw brown rice's water absorption (making it easier to absorb water) in subsequent processes, making it possible to simplify or eliminate the rice washing and soaking processes during cooking.This allows the grains to maintain an appropriate surface hardness after cooking, thereby maintaining a good grain texture after cooking (i.e., a satisfying feeling when eating).

[0024] The subsequent steps are performed automatically by a retort machine (not shown) based on a preset control amount. This retort machine is a device that has the function of sealing the raw material rice that has been introduced into a packaging container and cooking it, and the retort machine itself is a known device. The subsequent introduction step (step #2) is a step in which treated raw material brown rice that has been heat-treated using a steam sterilizer (hereinafter referred to as treated raw material brown rice) is introduced into the packaging container. In this introduction step (step #2), a predetermined amount of treated brown rice is introduced into each packaging container. In this embodiment, as an example, 30 g of treated raw material brown rice is measured and introduced into one packaging container. Furthermore, as the packaging container, a plastic tray, a metal can (steel can, aluminum can, etc.), a pouch (retort bag), etc. can be used.

[0025] The water-adding step (step #3) is a step of injecting raw water (water or a seasoning liquid containing water and seasoning; the same applies hereinafter) into a packaging container containing the processed raw brown rice. In this embodiment, as an example, 90 cc of raw water is injected into one packaging container. If too much raw water is added in this water-adding step, the cooked rice will lose its graininess after cooking; if too little raw water is added, the starch will be prone to retrogradation, making it difficult to eat without heating. Therefore, the water-adding step is configured to add raw water in an amount of approximately 300% by weight (preferably in the range of 290 to 310% by weight, and most preferably 300% by weight) of the processed raw brown rice. This allows the endosperm of the raw brown rice to absorb sufficient water, making the cooked rice easy to eat without heating, and maintaining a good graininess after cooking for a long period of time.

[0026] The sealing step (step #4) involves heat-sealing the packaging container (top lid) at a temperature appropriate for the container's characteristics, and hermetically sealing the processed raw brown rice and raw water inside the packaging container. The subsequent rice cooking step (step #5) involves cooking the processed raw brown rice in the packaging container. For example, if the packaging container is a plastic tray or a metal can (steel can, aluminum can, etc.), the processed raw brown rice is cooked in the packaging container at 118°C for 30 minutes, or if the packaging container is a pouch (retort bag), the processed raw brown rice is cooked in the packaging container at 118°C for 25 minutes. The subsequent cooling step (step #6) involves temporary cooling in the retort machine 1, and then cooling the cooked packaged cooked rice to, for example, 25°C using a chiller or the like. The subsequent container drying step (step #7) involves removing moisture from the surface of the packaging container by blowing air. The packaged cooked rice according to the present invention is produced through these steps. The packaged cooked rice produced in this manner can be easily eaten without heating, and provides a satisfying staple food, as will be described in detail later.

[0027] <3. About the Examples> FIG. 3 is a comparative photograph of packaged cooked rice produced by the method for producing packaged cooked rice according to an embodiment of the present invention and general packaged cooked rice (retort rice). More specifically, FIG. 3(a) is a comparative photograph showing the appearance when chopsticks are pierced into the cooked rice portion of each packaged cooked rice in an unheated state, and FIG. 3(b) is a comparative photograph showing the appearance when the rice is stirred with chopsticks. Both were stored for approximately one month after production. As shown in FIG. 3(a), in the packaged cooked rice according to the present invention, chopsticks can be pierced smoothly into the cooked rice portion in an unheated state (at room temperature), and as shown in FIG. 3(b), stirring with chopsticks loosens the grains in the cooked rice portion, allowing for smooth stirring. On the other hand, in the case of general packaged cooked rice (retort rice), as shown in FIG. 3(a), the cooked rice portion is solid, so chopsticks cannot be pierced without applying force, and furthermore, the grains stick together, making it difficult to stir smoothly. In this way, it was confirmed that the packaged cooked rice according to the present invention can be easily eaten without heating.

[0028] <4. Results of sensory test (texture evaluation)> The sensory test (evaluation of texture) was conducted under the following conditions by 18 randomly selected healthy adults. Each sample was placed in an individual container, and judgment was made according to the respective evaluation criteria for each sensory item. Table 1 shows the evaluation results for general packaged cooked rice (retort rice), Table 2 for general retort rice porridge, and Table 3 for the packaged cooked rice according to the present invention. [Table 1] [Table 2] [Table 3]

[0029] The sensory test (texture evaluation) showed that general packaged cooked rice is hard and crumbly and cannot be eaten as is, general retort pouch rice is soft and does not have a grainy texture but can be eaten as is, and the packaged cooked rice of the present invention can be eaten as is and is soft but has a grainy texture. This confirmed that the packaged cooked rice of the present invention can be easily eaten without heating, has a grainy texture, and can provide a satisfying feeling as a staple food.

[0030] The embodiments of the present invention have been described above. The present invention is not limited to the above-described embodiments. It goes without saying that the present invention can be modified appropriately within the scope of the technical concept. [Explanation of symbols]

[0031] a1,a2 germ part br1 Giant germ rice brown rice br2 Regular brown rice

Claims

1. A method for producing packaged cooked rice, comprising: a pouring step of pouring raw material brown rice into a packaging container; a hydration step of adding raw material water into the packaging container; a sealing step of hermetically sealing the raw material brown rice and raw material water in the packaging container; and a cooking step of cooking the raw material brown rice hermetically sealed in the packaging container, The raw brown rice is made of giant germ rice, A method for manufacturing packaged cooked rice, wherein in the water addition step, raw material water is added in an amount of approximately 300% by weight of the raw material brown rice placed in the packaging container.

2. Furthermore, a heated steam injection step is provided in which the raw material brown rice is subjected to a heat treatment with steam before the adding step, 2. The method for manufacturing packaged cooked rice according to claim 1, wherein the heated steam injection process comprises the steps of injecting pressurized heated steam onto the raw material brown rice for several seconds, and drying the raw material brown rice with hot air after the pressurized heated steam injection.

3. 3. The method for producing packaged cooked rice according to claim 2, wherein the raw material brown rice is low-amylose rice.

4. 4. The method for producing packaged cooked rice according to claim 3, wherein the sugar alcohol content of the raw material brown rice is 14 mg or more per 100 g of grain weight.

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