Frozen rice box lunch (BENTO)

Abstract

To provide a frozen rice Bento curbed in moisture reduction and flavor deterioration in the rice after treated by freezing and thawing processes, a frozen rice Bento improved in degradation of texture in the rice after treated by freezing and thawing processes, and so on.SOLUTION: Provided are a frozen rice Bento in a container, etc. including precooked rice laid thoroughly in the bottom part of the container and a precooked secondary food material disposed overlapped thereon, where the height of the precooked rice in the container is less than half the height in the inside dimension of the container, and the precooked secondary food material covers 85% or more of the surface of the precooked rice.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a frozen rice lunch box and the like. [Background technology]

[0002] In recent years, consumers have come to appreciate the convenience of being able to eat simply by heating and cooking in a microwave oven, and a large number of frozen foods, including frozen lunch boxes, are available on the market. However, frozen cooked rice is known to lose moisture and flavor during the freezing and thawing process, and uneven heating during thawing can cause deterioration in texture and flavor, so there are very few frozen lunch boxes on the market that contain cooked rice.

[0003] Patent Document 1 discloses that in a cooked frozen food product in which a frozen liquid food portion, made by freezing and solidifying a liquid food, is layered on top of a frozen solid food portion, made by freezing and solidifying a solid food including cooked rice, and frozen ingredients, made by freezing and solidifying ingredients, are exposed on the surface of the frozen liquid food portion, by including each in a specific mass ratio, the liquid food is arranged on top of the solid food in a good appearance when thawed, and a cooked frozen food product with a good texture and no uneven thawing can be obtained. However, the examples specifically describe only a cooked frozen food product using spaghetti as the solid food. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-121586 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a frozen rice lunch box in which the loss of moisture and deterioration of flavor in rice during the freezing and thawing processes, which are specific to frozen rice, are suppressed, and a frozen rice lunch box in which the deterioration in texture in rice during the freezing and thawing processes is improved. [Means for solving the problem]

[0006] As a result of extensive research into the above-mentioned problems, the inventors have discovered that in a frozen rice lunch box, by making the height of the rice in the container less than five-eighths of the internal height of the container and arranging the side dishes so that they cover the surface of the rice, it is possible to suppress the loss of moisture and deterioration of flavor in the rice during the freezing and thawing process, which are unique to frozen rice, and to improve the deterioration in the texture of the rice during the freezing and thawing process.Further research based on this finding has led to the completion of the present invention. That is, the present invention is as follows.

[0007] [1] A containerized frozen rice lunch having cooked rice spread in the bottom of the container and cooked side dishes placed on top of it, characterized in that the height of the cooked rice in the container is less than five-eighths of the height of the container's internal dimensions, and the cooked side dishes cover 80% or more of the surface of the cooked rice. [2] The lunch box according to [1] above, wherein the cooked rice is rice obtained by cooking non-glutinous rice containing 5% to 40% by weight of one or more selected from barley, glutinous rice, and mixed grain rice. [3] The lunch box according to [1] above, wherein the cooked rice is rice obtained by cooking non-glutinous rice containing 5% to 40% by weight of rolled barley. [4] A method for producing a frozen rice lunch, comprising the steps of: laying cooked rice in the bottom of a container so that the height of the cooked rice in the container is less than five-eighths of the height of the internal dimensions of the container; and arranging cooked side dishes on top of the cooked rice so that the cooked side dishes cover 80% or more of the surface of the cooked rice. [5] The manufacturing method described in [4] above, wherein the cooked cooked rice is cooked rice obtained by cooking non-glutinous rice containing 5% to 40% by weight of one or more selected from barley, glutinous rice, and mixed grain rice. [6] The method according to [4] above, wherein the cooked cooked rice is obtained by cooking non-glutinous rice containing 5% to 40% by weight of rolled barley. [Effects of the Invention]

[0008] The present invention can provide frozen rice lunches in which the loss of moisture and deterioration of flavor in rice during the freezing and thawing process is suppressed, and frozen rice lunches in which the deterioration of texture in rice during the freezing and thawing process is improved. [Brief explanation of the drawings]

[0009] [Figure 1] Figure 1 shows the percentage decrease in moisture content of cooked white rice before and after freezing and thawing, as measured in Example 1. The vertical axis represents the percentage decrease in moisture content from before freezing and thawing, and the horizontal axis represents the height of the cooked white rice (weight of the white rice) (pre represents before freezing and thawing). ns indicates no significant difference from the moisture content before freezing and thawing, p<0.05 and p<0.01 indicate significant differences from the moisture content before freezing and thawing (Dunnett's multiple comparisons test), and error bars indicate standard error. [Figure 2] FIG. 2 is a photograph showing the state in Example 2 in which 10, 8, 6, 4 or 0 gyoza (unthawed) were placed on the surface of cooked rice (from top left to bottom right). [Figure 3] Figure 3 shows the percentage decrease in moisture content in cooked white rice before and after freezing and thawing, measured in Example 2. The vertical axis represents the percentage decrease in moisture content from before freezing and thawing, and the horizontal axis represents the percentage of cooked white rice covered with dumplings (pre represents before freezing and thawing). Error bars indicate standard error. [Figure 4]Figure 4 shows the results of the sensory evaluation conducted in Test Example 1. The vertical axis represents the evaluation score, and the horizontal axis represents the ratio of white rice (R) to rolled barley (O) (for example, "R100:O0" represents "white rice:rolled barley = 100:0"). "w / o Gyoza" means that no gyoza were placed on the surface. Also, ns indicates no significant difference compared to the ratio of white rice:rolled barley = 100:0, *, **, and *** indicate significant differences (p<0.05, p<0.01, and p<0.001) from the ratio of white rice:rolled barley = 100:0 (Dunnett's multiple comparisons test), respectively. Error bars indicate standard error. [Figure 5] FIG. 5 is a photograph showing the state in Example 4 in which 11, 10, 9 or 7 pieces of fried chicken (unthawed) were placed on the surface of cooked rice (from left to right). [Figure 6] Figure 6 shows the percentage decrease in moisture content of cooked white rice before and after freezing and thawing, as measured in Example 4. The vertical axis represents the percentage decrease in moisture content from before freezing and thawing, and the horizontal axis represents the percentage of cooked white rice covered with fried chicken (pre represents before freezing and thawing). ns indicates no significant difference from the moisture content before freezing and thawing, p<0.01 and p<0.001 indicate significant differences from the moisture content before freezing and thawing (Dunnett's multiple comparisons test), respectively, and error bars indicate standard error. [Figure 7] 7 shows the results of the sensory evaluation conducted in Test Example 2. The vertical axis represents the evaluation score, and the horizontal axis represents the percentage of cooked white rice covered with fried chicken. ns indicates that there was no significant difference compared to the case without fried chicken, *, **, and *** indicate that there was a significant difference (p<0.05, p<0.01, and p<0.001) compared to the case without fried chicken (Dunnett's multiple comparisons test), respectively, and the error bars indicate the standard error. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1. Frozen rice lunch box The present invention provides a containerized frozen rice lunch having cooked rice spread at the bottom of the container and cooked side dishes placed on top of it, characterized in that the height of the cooked rice in the container is less than five-eighths of the height of the container's internal dimensions, and the cooked side dishes cover 80% or more of the surface of the cooked rice (hereinafter also referred to as the "lunch of the present invention").

[0011] In this specification, "cooked cooked rice" refers to cooked rice obtained by cooking (e.g., boiling) commonly eaten non-glutinous rice, and includes rice obtained by cooking polished rice, as well as brown rice, red rice, seasoned rice, pilaf, fried rice, dry curry, sushi rice, etc. Among these, rice obtained by cooking polished rice is preferred.

[0012] The non-glutinous rice is not particularly limited as long as it is a type that is commonly eaten, and examples thereof include varieties such as Koshihikari, Akitakomachi, Hitomebore, Yumepirika, and Nanatsuboshi.

[0013] Furthermore, in the present invention, non-glutinous rice may contain one or more selected from barley (such as barley including glutinous barley and pressed barley), glutinous rice, and multigrain rice, with non-glutinous rice including pressed barley being preferred. Pressed barley is made by pressing and flattening non-glutinous barley, and can be obtained, for example, by removing the husk and bran and polishing the non-glutinous barley, exposing it to steam, and then pressing and flattening it using a roller or the like. Furthermore, pressed barley also includes germ pressed barley, which retains the germ portion.

[0014] When the non-glutinous rice contains one or more selected from barley, glutinous rice, and multigrain rice, the proportion of the one or more selected from barley, glutinous rice, and multigrain rice in the non-glutinous rice is preferably 5% by weight to 40% by weight, more preferably 7% by weight to 38% by weight, even more preferably 10% by weight to 35% by weight, even more preferably 12% by weight to 33% by weight, and particularly preferably 15% by weight to 32% by weight, from the viewpoint of more effectively improving the deterioration in texture of cooked rice during the freezing and thawing process in frozen rice lunches.

[0015] In one embodiment of the lunch box of the present invention, the cooked cooked rice is cooked rice obtained by cooking non-glutinous rice containing 5% to 40% by weight of one or more selected from barley, glutinous rice, and multigrain rice.

[0016] Furthermore, in one aspect of the lunch box of the present invention, the cooked cooked rice is cooked rice obtained by cooking non-glutinous rice containing 5% to 40% by weight of rolled barley.

[0017] As used herein, "prepared side dishes" generally refer to cooked side dishes placed on top of rice in a rice bento box, and are not particularly limited. Side dishes can be classified into fluid and non-fluid side dishes. Fluid side dishes include side dishes placed on top of rice in a rice bowl, such as curry, while non-fluid side dishes include a wide variety of foods, such as meat, processed meat products (e.g., hamburger steaks, sausages, gyoza, etc.), fish, processed fish products (e.g., chikuwa, satsumaage, etc.), vegetables, and other prepared foods. These may be used alone or in combination. Among these, non-fluid side dishes are preferred, from the perspective of more effectively suppressing moisture loss and flavor deterioration in cooked rice during freezing and thawing. The "cooking" of a "prepared side dish" includes washing and cutting food ingredients (ingredients), as well as standard cooking methods depending on the type of side dish, such as boiling, grilling, or frying.

[0018] The container is not particularly limited as long as it is microwave-safe and can withstand freezing and thawing processes, and examples thereof include plastic containers, silicone containers, and ceramic containers commonly used for boxed lunches. Of these, plastic containers are preferred. The shape of the container is also not particularly limited as long as it is a shape commonly used for boxed lunches, and examples thereof include rectangular, cylindrical, oval, and bowl-shaped containers. The container may also have an internal divider.

[0019] In this specification, "cooked cooked rice spread out at the bottom of a container" is not particularly limited as long as it is cooked cooked rice spread out at the bottom of a container, but it is preferable that the cooked cooked rice is spread out at the bottom of the container so that the height is approximately uniform.

[0020] In the lunch box of the present invention, the height of the cooked rice spread at the bottom of the container is less than five-eighths of the height of the container's internal dimensions (hereinafter simply referred to as "container height"). However, from the viewpoint of more effectively suppressing moisture loss and flavor deterioration in the cooked rice during freezing and thawing, it is preferably less than half the height of the container, and more preferably less than half. Furthermore, the height of the cooked rice spread at the bottom of the container is preferably 5% to 62%, 5% to 50%, 8% to 45%, or 10% to 40% of the height of the container, more preferably 11% to 38%, 12% to 36%, 13% to 34%, 14% to 32%, or 15% to 30%, even more preferably 16% to 30%, 17% to 30%, 18% to 30%, or 19% to 30%, and particularly preferably 20% to 30%.

[0021] In addition, in the lunch box of the present invention, the cooked side dish covers 80% or more of the surface of the cooked rice, but from the viewpoint of more effectively suppressing moisture loss and deterioration of flavor during the freezing and thawing process, it is preferable that the cooked side dish covers 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more or 90% or more of the surface of the cooked rice, and it is preferable that the cooked side dish covers 91% or more, 92% or more of the surface of the cooked rice. It is more preferred that the cooked side dish covers 96% or more, 97% or more or 98% or more of the surface of the cooked rice, it is even more preferred that the cooked side dish covers 99% or more, 99.5% or more or 99.9% or more of the surface of the cooked rice, and it is especially preferred that the cooked side dish covers nearly 100% or 100% of the surface of the cooked rice.

[0022] Furthermore, in the lunch box of the present invention, the overall height of the cooked rice and cooked side dishes in the container is preferably 75% or more of the height of the internal dimensions of the container, more preferably 80% or more, 85% or more or 90% or more, even more preferably 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more or 99% or more, and is particularly preferably approximately 100% or 100%.

[0023] Next, a method for producing the lunch box of the present invention will be described.

[0024] First, cooked rice is laid out in the lower part of a container so that the height of the cooked rice in the container is less than five-eighths of the height of the container's internal dimensions, and then cooked side dishes are placed on top of the cooked rice so that the cooked side dishes cover 80% or more of the surface of the cooked rice. The method of laying the cooked rice out in the lower part of the container and the method of placing the cooked side dishes on top of the cooked rice are methods commonly used in preparing boxed lunches. Here, the cooked rice and cooked side dishes may be pre-frozen.

[0025] Next, the obtained pre-freezing frozen rice lunch box is frozen typically at -10°C to -78°C, preferably -15°C to -78°C, more preferably -15°C to -45°C, typically for 30 minutes to 36 hours, preferably 1 hour to 24 hours, more preferably 5 hours to 24 hours.

[0026] In the lunch box of the present invention, the loss of moisture and deterioration of flavor in cooked rice during the freezing and thawing process are suppressed, and the deterioration in texture of cooked rice during the freezing and thawing process is improved. Furthermore, in the lunch box of the present invention where the non-glutinous rice contains one or more selected from barley, glutinous rice, and multigrain rice, the deterioration in texture of cooked rice during the freezing and thawing process is further improved.

[0027] 2. Manufacturing method of frozen rice lunches The present invention also provides a method for producing a frozen rice lunch (hereinafter also referred to as "the production method of the present invention"), which includes a step of laying cooked rice in the lower part of a container so that the height of the cooked rice in the container is less than five-eighths of the height of the internal dimensions of the container, and a step of arranging a cooked side dish on top of the cooked rice so that the cooked side dish covers 80% or more of the surface of the cooked rice, as well as a method for suppressing moisture loss and deterioration of flavor in frozen rice lunches and a method for improving deterioration in the texture of cooked rice during freezing and thawing (hereinafter collectively referred to as "the methods of the present invention").

[0028] The "container," "cooked rice," and "cooked side dish" are as explained above for the lunch box of the present invention.

[0029] In this specification, "spreading cooked rice in the lower part of a container" is not particularly limited as long as it is a form in which cooked rice is spread in the lower part of a container, but it is preferable that the cooked rice is spread in the lower part of the container so that the height is approximately uniform.

[0030] The manufacturing method of the present invention and the method of the present invention can be carried out in the same manner as the manufacturing method of the present invention for the lunch box described above for the lunch box of the present invention.

[0031] In the manufacturing method and method of the present invention, cooked cooked rice is spread out in the lower part of a container so that the height of the cooked rice in the container is less than five-eighths of the height of the internal dimensions of the container (hereinafter simply referred to as the "height of the container"); however, from the viewpoint of more effectively suppressing the loss of moisture and deterioration of flavor that are specific to frozen cooked rice, it is preferable to spread the cooked rice so that it is less than half the height of the container, and more preferably less than half. Furthermore, it is preferable to spread the cooked rice in the lower part of the container so that the height of the cooked rice in the container is 5% to 62%, 5% to 50%, 8% to 45%, or 10% to 40% of the height of the container, more preferably 11% to 38%, 12% to 36%, 13% to 34%, 14% to 32%, or 15% to 30%, even more preferably 16% to 30%, 17% to 30%, 18% to 30%, or 19% to 30%, and particularly preferably 20% to 30%.

[0032] Furthermore, in the manufacturing method and method of the present invention, the cooked side dish is arranged so that it covers 80% or more of the surface of the cooked cooked rice. From the viewpoint of more effectively suppressing moisture loss and deterioration of flavor during the freezing and thawing process, it is preferable to arrange it so that it covers 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, or 90% or more of the surface of the cooked cooked rice, it is more preferable to arrange it so that it covers 91% or more, 92% or more, 93% or more, 94% or more, or 95% or more of the surface of the cooked cooked rice, it is even more preferable to arrange it so that it covers 96% or more, 97% or more, or 98% or more of the surface of the cooked cooked rice, it is even more preferable to arrange it so that it covers 99% or more, 99.5% or more, or 99.9% or more of the surface of the cooked cooked rice, and it is particularly preferable to arrange it so that it covers almost 100% or 100% of the surface of the cooked cooked rice.

[0033] Furthermore, in the manufacturing method and method of the present invention, the overall height of the cooked rice and cooked side dish in the container is preferably 75% or more of the height of the internal dimensions of the container, more preferably 80% or more, 85% or more, or 90% or more, even more preferably 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more, and particularly preferably approximately 100% or 100%.

[0034] By using the manufacturing method and method of the present invention, it is possible to obtain frozen rice lunches in which the loss of moisture and deterioration of flavor in the rice during the freezing and thawing process is suppressed, and frozen rice lunches in which the deterioration of texture in the rice during the freezing and thawing process is improved.

[0035] In one embodiment of the production method and method of the present invention, the cooked cooked rice is obtained by cooking non-glutinous rice containing 5% to 40% by weight of one or more selected from barley, glutinous rice, and multigrain rice. By using this cooked rice, a frozen rice lunch box can be obtained in which the deterioration of the texture of cooked rice during the freezing and thawing process is further improved.

[0036] Furthermore, in the production method of the present invention and one embodiment of the method of the present invention, the cooked cooked rice is cooked rice obtained by cooking non-glutinous rice containing 5% to 40% by weight of rolled barley.

[0037] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples in any way. [Example]

[0038] In the examples, the following raw materials, devices, and equipment were used unless otherwise specified. Container: A pulp-molded container (homemade) with outer dimensions of 20.4 cm length, 15.8 cm width, and 4.1 cm height, and inner dimensions of 20.0 cm length, 15.4 cm width, and 4.0 cm height. Rice cooker used: NP-VL10 rice cooker (manufactured by Zojirushi Corporation) White rice: Yumepirika polished rice (manufactured by Nagoya Shokuryo Co., Ltd.) Rolled barley: Rolled barley with germ (made by Hakupaku Co., Ltd.) Wash-free rice: Wash-free Koshihikari rice from Niigata (manufactured by MM Rice Co., Ltd.) Gyoza (cooked frozen gyoza): "Gyoza in the microwave" (Ajinomoto Frozen Foods Co., Inc.) (unthawed) Fried chicken (cooked frozen fried chicken): "Soft fried chicken in the microwave" (Ajinomoto Frozen Foods Co., Inc.) (unthawed) Moisture meter: "Rice Moisture Checker G-50" (manufactured by Atago Co., Ltd.)

[0039] Example 1 (Effect of rice height) Quick-cooking was performed using polished rice (non-rinse rice). After cooking, the rice was cooled to body temperature and the moisture content was measured using a moisture meter. Moisture content was measured at three points (near both ends of the diagonal and near the center) of the container (same below), and the average moisture content was 64%. Next, the cooked polished rice was spread evenly in a container to heights of 0.5 cm (130 g polished rice; 12.5% of the container height), 1.0 cm (180 g polished rice; 25% of the container height), 2.0 cm (250 g polished rice; 50% of the container height), and 3.0 cm (400 g polished rice; 75% of the container height). Ten gyoza were placed on top of each spread, covering the surface of each cooked polished rice to approximately 100%. The container was then wrapped twice in food-grade plastic wrap to prepare pre-frozen gyoza bento lunch boxes. Each of the resulting gyoza bento boxes was frozen in a -30°C freezer for over 18 hours before being thawed in a microwave oven (500W). Three minutes after thawing, the moisture content of the cooked rice was measured using a moisture meter. The moisture content reduction rate of the cooked rice from before freezing and thawing is shown in Figure 1 (N=3).

[0040] As shown in Figure 1, when the height of the cooked rice was 0.5 cm and 1.0 cm, the moisture content of the cooked rice was almost maintained even after freezing and thawing. On the other hand, when the height of the cooked rice was 3.0 cm, the moisture content of the cooked rice significantly decreased after freezing and thawing.

[0041] Example 2 (Effect of the ratio of side dishes covering the surface of cooked rice 1) Quick-cooking was performed using polished rice (non-rinse rice). After cooking, the rice was cooled to body temperature and the moisture content was measured using a moisture meter. The average moisture content was 64%. The cooked polished rice was then spread evenly in a container to a height of 1.0 cm (180 g of polished rice; 25% of the container's height), and 10, 8, 6, 4, or 0 gyoza were placed on top (Figure 2; 100%, 80%, 60%, 40%, and 0% of the surface of the cooked rice were covered with gyoza, respectively). Each container was then wrapped twice in plastic wrap to prepare pre-frozen gyoza bento boxes. The resulting pre-frozen gyoza bento boxes were frozen in a -30°C freezer for at least 18 hours and then thawed in a 500W microwave oven. The moisture content of the cooked polished rice was then measured using a moisture meter 3 minutes after thawing. Figure 3 shows the rate of decrease in moisture content of cooked white rice from before freezing and thawing (N=3).

[0042] As shown in Figure 3, when 100% of the surface of the cooked rice was covered with dumplings, the moisture content of the cooked rice was almost maintained even after freezing and thawing. On the other hand, when only 60% or less of the surface of the cooked rice was covered, the moisture content decreased significantly.

[0043] Example 3 (Effect of rolled barley content) Quick-cooking rice was performed using mixtures of pre-washed white rice and pressed barley in ratios of 100:0, 85:15, 70:30, 55:45, 20:80, and 0:100. After cooking, the rice was allowed to cool to body temperature. Next, the cooked white rice / pressed barley mixture was layered in a container to a height of 1.0 cm (180 g of white rice; 25% of the container's height). Ten gyoza dumplings were placed on top, covering the surface of each mixture almost 100%. Each container was then wrapped twice in food-grade plastic wrap to prepare the pre-frozen gyoza bento lunches. A control lunch box containing only cooked white rice, without any gyoza on top, was also prepared. Each of the resulting gyoza bento boxes (including the control bento box containing only cooked white rice) was frozen in a -30°C freezer for over 18 hours before being thawed in a microwave oven (500W). Three minutes after thawing, the moisture content of the cooked white rice / rolled barley was measured using a moisture meter. The results showed that, in all cases except for the control bento box containing only cooked white rice, the moisture content of the cooked white rice / rolled barley was largely maintained even after freezing and thawing.

[0044] Test Example 1 (Effect of rolled barley content on sensory evaluation) The cooked white rice / rolled barley in each thawed gyoza bento box obtained in Example 3 was evaluated by a panel of four experts skilled in evaluation using a relative evaluation method based on the five categories of overall evaluation, appearance, aroma, taste, stickiness, and hardness, conducted by the Japan Grain Inspection Association, a method conforming to the Food Agency's "Procedures for Rice Taste Testing" (1966) and rating the rice on a seven-point scale from -3 to +3, with the reference rice being given a score of 0. The average scores of the four experts were calculated. The results are shown in Figure 4. In addition, the appearance and aroma of the bento box containing only cooked white rice, without any gyoza on top, were given a score of 0 by all four expert panel members.

[0045] As shown in Figure 4, when a 70:30 or 85:15 mixture of polished rice and rolled barley was used, the overall evaluation, appearance, aroma, stickiness, and hardness were all rated higher than when 100% polished rice was used. In particular, when a 70:30 mixture of polished rice and rolled barley was used, the highest evaluation score was obtained in all of the above categories.

[0046] Example 4 (Effect of the ratio of side dishes covering the surface of cooked rice 2) Pre-cooked white rice (no-rinse rice) was cooked using the quick-cooking method. After cooking, the rice was cooled to body temperature and the moisture content was measured using a moisture meter. The average moisture content was 62%. The cooked white rice was then spread evenly in a container to a height of 1.0 cm (180 g of white rice; 25% of the container's height), and 11, 10, 9, 7, or 0 pieces of fried chicken were placed on top (Figure 5; 100%, 90.9%, 81.8%, 63.6%, and 0% of the rice surface was covered with fried chicken, respectively). Each container was then wrapped twice in food-grade plastic wrap to prepare pre-frozen fried chicken bento boxes. The resulting pre-frozen fried chicken bento boxes were frozen in a -30°C freezer for at least 18 hours and then thawed in a 500W microwave. The moisture content of the cooked white rice was then measured using a moisture meter 3 minutes after thawing. Figure 6 shows the rate of decrease in moisture content of cooked white rice from before freezing and thawing (N=4).

[0047] As shown in Figure 6, when 100% or 90.9% of the surface of the cooked rice was covered with fried chicken, the moisture content of the cooked rice was almost maintained even after freezing and thawing. On the other hand, when only 63.6% or less of the surface of the cooked rice was covered, the moisture content decreased significantly.

[0048] Test Example 2 (Effect of rolled barley content on sensory evaluation) The cooked white rice in each of the thawed fried chicken lunch boxes obtained in Example 4 was subjected to a sensory evaluation of six items: overall evaluation, appearance, aroma, taste, stickiness, and hardness, conducted by the Japan Grain Inspection Association, a method based on the Food Agency's "Rice Taste Testing Guidelines" (1966) (https: / / www.kokken.or.jp / test01.html, "Delicious Taste," edited by Kinya Kushibuchi, Vol. 2, Agriculture, Forestry, and Fisheries Technology Information Association, 1996, pp. 87-90). Four expert panelists skilled in evaluation evaluated the three items of overall evaluation, stickiness, and hardness using a relative evaluation method on a 7-point scale from -3 to +3, with the standard rice assigned a score of 0. The average scores of the four expert panelists were calculated. The results are shown in Figure 7.

[0049] As shown in Figure 7, when 100% or 90.9% of the surface of the cooked white rice was covered with fried chicken, the overall evaluation, stickiness, and hardness were all rated higher than when only 81.8% or less of the surface of the cooked white rice was covered. [Industrial Applicability]

[0050] The present invention can provide frozen rice lunches in which the loss of moisture and deterioration of flavor in the rice during the freezing and thawing process is suppressed, and frozen rice lunches in which the deterioration of the texture of the rice during the freezing and thawing process is improved, etc. Therefore, the present invention is useful in the food industry field.

Claims

1. This frozen rice lunch box is a container containing cooked rice spread in the bottom of the container and cooked side dishes placed on top of it, characterized in that the height of the cooked rice in the container is less than five-eighths of the height of the inside dimensions of the container, and the cooked side dishes cover 80% or more of the surface of the cooked rice.

2. 2. The lunch box according to claim 1, wherein the cooked cooked rice is cooked rice obtained by cooking non-glutinous rice containing 5% to 40% by weight of one or more selected from barley, glutinous rice, and multigrain rice.

3. 2. The lunch box according to claim 1, wherein the cooked rice is obtained by cooking non-glutinous rice containing 5% to 40% by weight of rolled barley.

4. The method for producing a frozen rice lunch includes a step of spreading cooked rice in the lower part of a container so that the height of the cooked rice in the container is less than five-eighths of the height of the inside dimension of the container, and a step of arranging cooked side dishes on top of the cooked rice so that the cooked side dishes cover 80% or more of the surface of the cooked rice.

5. The method according to claim 4, wherein the cooked rice is obtained by cooking non-glutinous rice containing 5% by weight to 40% by weight of one or more selected from barley, glutinous rice, and multigrain rice.

6. The method according to claim 4, wherein the cooked rice is obtained by cooking non-glutinous rice containing 5% by weight to 40% by weight of rolled barley.

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