JP7362233B2 - Container for storing cooked rice - Google Patents

Description

The present invention relates to a container for storing cooked rice made of synthetic resin that can store cooked rice and is suitable for microwave heating.

Refrigerated storage and frozen storage are well known methods for preserving food for short or long periods of time. Convenient storage methods for food include storing the food in a container with a lid made of synthetic resin such as plastic, and storing the food by wrapping it over the food placed on a plate. However, these methods cannot sufficiently suppress the drying of foods, resulting in a problem in that the texture and taste of the foods are significantly impaired.

Furthermore, when eating food that has been stored in a refrigerator or a freezer, the food is often heated, and microwave heating using a microwave oven is commonly used as a heating method. However, when refrigerated or frozen food is heated by microwave heating, some parts of the food are easily heated and some parts are not easily heated, resulting in uneven heating of the food. The heating unevenness is caused by the fact that the induction loss coefficient (the rate at which radio wave energy is absorbed and converted into thermal energy) of water (5℃) is 5 to 15, while the induction loss coefficient of ice (-12℃) is 0. 003, this is mainly due to the fact that more microwaves are absorbed in the melted part than in the frozen part, increasing the temperature difference.

Cooked rice is an example of microwave heating of refrigerated or frozen food. In the case of cooked rice, it is known that storing it in the refrigerator impairs its flavor, so storing it in the freezer is generally recommended.

However, when frozen cooked rice is sealed in a container and frozen, the evaporated water cools and condenses, accumulating at the bottom of the container. If microwave heating is performed in this state, the cooked rice at the bottom absorbs the moisture, which may significantly impair the texture, taste, etc. of the cooked rice.

As a means to solve such problems, techniques have been proposed in which the shape of the container is modified. For example, in Patent Document 1, a convex portion having a corner that projects vertically is provided at the bottom of the container, and a plane surrounded by the convex portion is formed at the bottom of the container, thereby concentrating microwaves on the convex portion having the corner. , a microwave cooking container that does not cause uneven heating has been proposed.

Furthermore, Non-Patent Document 1 proposes a food storage container in which uneven heating is improved by providing a convex portion on the inner bottom of the container. In addition, Non-Patent Document 2 proposes a container for storing cooked rice that has a double structure by providing an inner container with a hole inside the container body.

Patent Document 2 proposes a container for storing cooked rice that is equipped with a holding space for holding water at the bottom of the container body and that makes it possible to separate cooked rice and water.

Japanese Patent Application Publication No. 9-215594 Japanese Patent Application Publication No. 2006-304670

"Kichinto-san rice frozen storage container", product information, [online], Kureha Co., Ltd., [searched on November 30, 2013], Internet <URL: http://kurelife.jp/products/ricecontainer/>

"Excellent rice preservation" product information, [online], Ebisu Co., Ltd. homepage, [searched on November 30, 2013], Internet <URL: http://www.ebisu-grp.co.jp/products/frozen- storage.html＞

The act of simply heating and eating refrigerated or frozen food using microwave heating is a common practice in ordinary households, and consumers' desire to enjoy reheated food is increasing. Therefore, it is an important issue to reduce uneven heating during the storage and reheating processes, and to maintain the texture and taste of the food.

The shape of the container disclosed in Patent Document 1 and Non-Patent Document 1 improves heating unevenness during microwave heating, but moisture that condenses at the bottom of the container during frozen storage is dissolved by heating and absorbed into the food. The problem remains that the texture and taste are lost when the food is cooked.

In addition, the shape of the container disclosed in Patent Document 2 and Non-Patent Document 2 can improve heating unevenness during microwave heating and separate moisture condensed at the bottom of the container from the food. Compared to its size, there are other issues such as the capacity of the food that can be stored in the inner container is small, making it bulky in the freezer, making it difficult to clean after use, and making storage difficult as the same containers cannot be stacked when not in use. do. Another disadvantage is that it is expensive due to the structure in which the inner container is provided.

Note that the above-mentioned problem is not limited to the preservation of cooked rice, but also applies to other foods. For example, when frozen foods such as frozen shumai, frozen vegetables, and frozen takoyaki are placed in a container and thawed and heated using microwave heating, uneven heating occurs. There is a problem with the loss of texture and taste.

In view of the above-mentioned problems, the present invention provides a method for cooking rice that suppresses uneven heating of cooked rice and does not impair the texture and taste of cooked rice when heated cooked rice stored in a refrigerator or frozen is heated with microwaves. The purpose is to provide containers for storing rice .

As a result of intensive studies to solve the above problems, the present inventor focused on the cohesive heat transfer effect of water vapor, and created a structure that connects the concave portions of the entire container by providing unevenness on the bottom and wall surfaces of the container. We have discovered that water vapor generated from food during wave heating can be circulated throughout the container to reduce uneven heating, and that condensed water generated during storage or reheating can be separated from the food at the bottom of the container.

That is, the present invention is configured as follows.
[1] A container for storing cooked rice that is composed of a bottom, a side wall, and a flange, and has an open top, and the side wall has a plurality of gas or liquid gases extending vertically from the flange toward the bottom. A flow path is formed, and the bottom portion includes a recess and a convex portion, and the recess and the convex portion form a circulation retention portion in which gas or liquid flowing through the flow path circulates or remains, and the flange portion The convex portion is not formed on an extension of the gas or liquid flow path formed vertically toward the bottom, and the flow path and the recess function as a flow path even when cooked rice is stored. Connected container for storing cooked rice .
[2] The cooked rice storage container according to [1] above, wherein the flow path has a groove shape formed toward the bottom.
[3] The container for storing cooked rice according to [2] above, wherein the distance between the vertices of the convex portions adjacent to each other is 1 to 9 mm.
[4] The cooked rice storage container according to [3] above, wherein the depth of the recess is 0.7 to 3 mm.
[5] The cooked rice storage container according to [3] or [4] above, wherein the volume of the recess space formed by the recess is 1 to 25 cm ³ per 100 cm ² of the projected area of the bottom.
[6] The cooked rice storage container according to any one of [3] to [5] above, wherein the surface area of the bottom is 1.5 times or more the projected area of the bottom.

According to the present invention, when cooked rice stored in a refrigerator or frozen is heated with microwaves, uneven heating of the cooked rice is reduced, and water condensed at the bottom of the container is separated from the cooked rice , thereby improving texture. It is possible to obtain a container for storing cooked rice that does not impair its taste.

A perspective view showing the overall configuration of a food storage container according to an embodiment of the present invention A plan view of a food storage container according to an embodiment of the present invention A front view of a food storage container according to an embodiment of the present invention End view of AA' in Figure 2 An enlarged sectional view of the bottom of the food storage container according to the embodiment of the present invention An enlarged plan view of the bottom of the food storage container according to the embodiment of the present invention Schematic diagram showing the space formed by the recess Schematic diagram showing the space formed by the recess Schematic diagram showing the space formed by the recess Enlarged sectional view of the bottom of a food storage container according to another embodiment An enlarged plan view of the bottom of a food storage container according to another embodiment Schematic diagram of a flow path and ridge portion (vertical groove shape) of a food storage container according to another embodiment A schematic diagram of a flow path and a ridge portion or a concave portion and a convex portion of a food storage container according to another embodiment (through-joint shape) A schematic diagram of a flow path and a ridge portion or a concave portion and a convex portion of a food storage container according to another embodiment (horse-tread joint shape) Schematic diagram of concave portions and convex portions of a food storage container according to another embodiment (quarter joint shape) Schematic diagram of concave portions and convex portions of a food storage container according to another embodiment (mesh pattern) Schematic diagram of concave portions and convex portions of a food storage container according to another embodiment (basket shape) Schematic diagram of concave portions and convex portions of a food storage container according to another embodiment (three-eyed checkerboard shape) Plan view of food storage container according to Comparative Example 2

DESCRIPTION OF THE PREFERRED EMBODIMENTS A mode for carrying out the present invention (hereinafter referred to as "this embodiment") will be described in detail with reference to the drawings as necessary. Note that the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist.

The food storage container 1 (hereinafter simply referred to as "container 1") is a container mainly made of synthetic resin, and as shown in FIGS. It is a box-shaped body with an open top, consisting of a side wall 3 and a flange 4 formed at the upper end.

As is particularly clear from the AA end view of FIG. 4, the bottom portion 2 includes a plurality of recesses 21 that serve as circulation and retention portions in which gas or liquid circulates or remains, and a convex portion 22 formed between adjacent recesses 21. and has. The recessed part 21, which has a planar shape in FIGS. 2 and 6, has a semicircular cross-sectional shape as shown in FIGS. 4 and 5, and has a spherical shape as a whole, and the convex part 22 has a square shape in a planar view. It has a roughly trapezoidal cross section. Further, as is clear from FIGS. 1 and 4, the bottom portion 2 includes two step portions 23 on both sides of the container 1 in the longitudinal direction, the surfaces of the bottom portion 2 being raised.

As shown in FIGS. 1 to 3, the side wall portion 3 has a plurality of channels 31 formed in a vertical direction from the flange portion 4 of the container 1 toward the bottom portion 2. The flow path 31 is formed between the convex ridge portions 32 of the side wall portion 3, and is formed in the shape of a groove in the side wall portion 3.

The liquid flowing through the channel 31 formed in the side wall 3 heads toward the recess 21 in the bottom 2 and stays there, while the gas such as water vapor generated in the container 1 flows from the channel 31 in the side wall 3 to the bottom. The liquid flows toward the recess 21 of No. 2, flows into the recess 21, and is configured as a circulation retention section that can be circulated. In other words, the flow path 31 and the recess 21 are connected as a flow path.

Here, as shown in FIG. 5, the distance L between the vertices of the convex portions 22 on the bottom portion 2 is preferably 1 to 9 mm. Within this range, cooked rice grains will be less likely to fit into the recess 21 and will be easier to clean after use. More preferably, the distance L between the vertices of the convex portions 22 is 2 to 5 mm.

Note that the distance L between the vertices of the convex portions 22 is a value obtained by measuring the distance between the vertices of adjacent convex portions 22. Here, the apex of the convex portion 22 means the distance between the maximum points when the cross-sectional shape of the convex portion 22 has a maximum height such as an arc, a triangle, or a pentagon; , hexagon, etc., which have a flat part without a maximum point, mean the distance between the centers of the flat parts.

Further, the depth H of the recess 21 formed in the bottom portion 2 is preferably 0.7 to 3 mm. When the depth H is 0.7 mm or more, for example, moisture that condenses when cooked rice is heated with microwaves can be sufficiently accommodated in the recess 21, and is difficult to absorb into the cooked rice on the bottom 2 of the container 1, resulting in poor taste. It is possible to maintain good texture and texture. On the other hand, if the depth H is 3.0 mm or less, it can be cleaned with a sponge or an automatic dishwasher, the space (insulation layer) between the cooked rice and the freezer is appropriate, and the starch aging The residence time in the temperature range (0 to 10°C) is shortened, and the taste and texture of cooked rice can be maintained well. More preferably, the depth H of the recess 21 is 0.7 to 2 mm.

Note that the depth H of the recess 21 refers to the height difference between the apex of the protrusion 22 and the deepest point of the adjacent recess 21.

The volume V of the space formed by the recess 21 of the bottom 2 is preferably 1 to 25 ^{cm 3 per} 100 cm 2 of the projected area of the entire bottom 2 in plan view. In this range, the water that condenses when the cooked rice is heated in the microwave can be easily accommodated in this space, and the water does not overflow from the space, making it difficult to touch the bottom of the cooked rice, resulting in good taste and texture. can be maintained.

Here, the volume V of the space means a region where the recess 21 functions as a circulation retention section, that is, a region where liquid can accumulate. That is, among the three patterns shown in FIGS. 7 to 9, the shaded area is the space formed by the recess 21 , and the total volume of the shaded area is the volume V herein. The pattern shown in FIG. 7 in which a liquid reservoir is evenly formed by the recesses 21 and the projections 22, and the height of the apex of the projections 22 as shown in FIG. In the pattern shown in FIG. 9, recesses 21 and protrusions 22 are formed diagonally toward the center, and as one approaches the center, the height of the apex of the protrusions 22 becomes lower, and the bottom of the recesses 21 also lowers. The pattern is such that the space formed by the recess 21 as a liquid pool changes accordingly.

The surface area of the bottom portion 2, that is, the sum of the area of the recesses 21 and the surface areas of the convex portions 22 of the bottom portion 2 is preferably 1.5 times or more the projected area of the entire bottom portion 2 in a plan view. If it is 1.5 times or more, when food is put inside the container 1, the adhesion area to the bottom 2 of the container 1 becomes smaller, the adhesion of the contents to the bottom 2 of the container 1 is reduced, and the contents are Easy to take out.

The height 1L (see Figure 3) of the container 1 is not particularly limited, and may be the minimum height that can store food such as cooked rice, but it is preferably 20 to 150 mm. , is preferable because the efficiency of heating with microwaves is high. Further, although there is no particular restriction on the area of the bottom 2 and the opening of the container 1 of this embodiment, if the length in the longitudinal direction of the bottom 2 is 300 mm or less, it can be easily stored in a household refrigerator or a cupboard. Therefore, it is preferable.

Further, in this embodiment, the container 1 is preferably made of synthetic resin as described above. If it is made of synthetic resin, it can be stored in refrigeration or frozen storage, and it can be heated directly in the microwave. The synthetic resin material is not particularly limited, and examples include low density polyethylene (LDPE), high density polyethylene (HDPE), polystyrene, crystalline polyethylene terephthalate, amorphous polyethylene terephthalate, polyvinyl chloride, polycarbonate, and polypropylene. It will be done. Further, the synthetic resin material may be used alone or in combination. Among them, polypropylene is preferable because it is excellent in heat resistance, cold resistance, moldability, and cost.

Further, the method of molding the container 1 may be performed using a well-known technique, such as thermoforming, injection molding, vacuum forming, and the like. When forming using the vacuum forming method, if the sheet thickness before forming is 0.8 to 2.5 mm, it will maintain thermal conductivity and have sufficient moisture barrier and odor barrier properties, making it difficult to dry the stored food. This is preferable because it can prevent the adhesion of frozen odor.

Here, as shown in the enlarged view of FIG. 6, the shape of the recess 21 provided in the bottom part 2 is shown to be square, but the present invention is not limited to this embodiment, and any shape can be selected. be. Examples include not only geometric patterns such as circles, ovals, rectangles, rhombuses, triangles, and polygons, but also shapes with design features such as star shapes, heart shapes, bale shapes, diamond shapes, etc.; single shapes, Alternatively, multiple types of shapes may be used simultaneously.

In addition to the shape shown in FIG. 5, the cross-sectional shape of the convex portion 22 provided on the bottom portion 2 can also be selected from any desired shape. For example, as shown in FIG. 10 and FIG. It is also possible that all of the convex portions 22 have a circular cross section. Note that when the purpose is to prevent food stored in the container 1, particularly cooked rice, from adhering to the bottom portion 2, the cross-sectional shape of the convex portion 22 is preferably circular, triangular, or quadrangular.

On the other hand, various shapes can be considered for the flow passage 31 and the ridge part 32 formed in the side wall part 3, but the flow passage 31 installed in the wall surface in order to promote the circulation of water vapor throughout the container 1 is the shape of the flange part 3. Preferably, the shape forms a series of flows from the side toward the bottom 2. Therefore, the shape of the flow path 31 when viewed from the front includes, for example, a vertical groove shape, a through joint shape, a tread joint shape, and a quarter joint shape, as schematically shown in FIGS. 12 to 15.

A plurality of convex portions 22 installed on the bottom portion 2 are independently arranged on at least a portion of the inner surface of the bottom portion 2. The arrangement method at this time is not particularly limited, but a structure in which the spaces formed by the recesses 21 are connected in series is preferable because water vapor can be circulated throughout the container. Other forms of such a structure include, for example, as shown in FIGS. 13 to 18, in plan view, a through-joint shape, a horse-stepped joint shape, a quarter-joint shape, a mesh shape, a basket shape, a three-eyed checkerboard shape, etc. It will be done.

As shown in FIGS. 1 and 4, the stepped portions 23 in which the surface of the bottom portion 2 is raised are formed on both sides of the container 1 in the longitudinal direction, but in the present invention, steps 23 are formed within a range that does not impair the solution of the problem. In this case, a stepped portion 23 can be formed that raises a portion or multiple portions of the bottom portion 2 of the container 1 toward the contents. Further, in addition to the container main body of this embodiment, auxiliary materials such as a colander, a steam valve, a drain plug, a moisture absorbing layer, and an inner lid may be installed within a range that does not impair the solution of the problems of the present invention.

The shape of the container 1 of this embodiment is not particularly limited, and may be any shape such as square, rectangle, circle, oval shape, bowl shape, etc. as long as it can store food such as cooked rice. There may be. Further, it is preferable that the lid combined with the container 1 has appropriate airtightness when fitted to the flange portion 4 of the container 1. Thereby, air outside the container 1 can be prevented from entering the container as much as possible, and leakage of the contents of the container can be prevented as much as possible when the container 1 is overturned.

Hereinafter, the present embodiment will be described in detail with reference to Examples, but the present embodiment is not limited to these Examples.

The method for manufacturing the food storage containers prepared in Examples and Comparative Examples is as follows.
A food storage container 1 having the shape shown in FIGS. 1 to 3 was manufactured by vacuum forming a polypropylene sheet (thickness: 1.2 mm).

The dimensions of the obtained food storage container 1 are listed in Table 1. The method for measuring dimensions is as follows.
<Measurement of distance between vertices>
The distance L between the vertices (see Figure 5) is measured by cutting a 1 mm thick section with a small cutter so as to include two or more adjacent vertices among the vertices, and observing the cross section with a microscope. The distance between adjacent vertices was measured.

<Measurement of depth of recess>
The depth H of the concave portion 21 (see FIG. 5) is determined by the distance between the apex of the convex portion 22 and the convex portion 22 when a cross section of a section prepared in the same manner as the measurement of the distance L between the apexes is observed with a microscope. The height difference between adjacent recesses 21 and the most recessed portion in the depth direction was measured.

<How to calculate projected area>
The projected area was calculated by measuring the length in the transverse direction and the length in the longitudinal direction of the bottom portion 2 of the bottom projection of the container 1 using a caliper, and multiplying these values.

<How to calculate the volume of the space formed by the bottom and the concave and convex parts installed at the bottom>
It was calculated from the measurement results of the inter-vertex distance L and the depth H of the recess 21, which were measured by measuring the distance between the vertices of the protrusions 22 and the depth H of the recess 21.
In addition, the preparation method and evaluation method for cooked rice used in Examples and Comparative Examples are as follows.

<How to prepare cooked rice>
Using the food storage containers 1 of Examples and Comparative Examples, preserved cooked rice was prepared according to the following procedures (1) to (5).

(1) Cooking rice: 600 g of Koshihikari rice from Mie Prefecture and 798 g of tap water (1.33 times the weight of the unwashed rice) were cooked in an IH electric pot (manufactured by Zojirushi) with the wash-free rice course selected.
(2) Filling: Immediately after cooking the rice using method (1), mix well with a ladle so that the cooked rice in the pot is evenly distributed, and then pour 180g of the rice into a food storage container so that the cooked rice inside the container has a uniform thickness. The container was filled to the desired temperature and sealed using a lid with a structure that allows it to be sealed.
(3) Cooling: The cooked rice after being sealed was allowed to cool at room temperature (23°C) for 30 minutes.
(4) Freezing: After confirming that the temperature of the cooked rice in the container was below 60°C, it was stored frozen for 18 hours in the freezer compartment of a refrigerator (Hitachi RG5700G).
(5) Reheating: The frozen rice frozen using the above method was heated in a microwave oven (RE-26A manufactured by SHARP) with the output set to 500 W for 3 minutes.

<Sensory test of cooked rice taste after frozen storage>
A sensory evaluation of cooked rice was conducted by 100 housewives in their 20s to 50s. The cooked rice prepared by the method for preparing cooked rice described above was taken out and divided into two parts in the thickness direction, and divided into an upper part corresponding to the upper half in the filling direction and a lower part corresponding to the lower half in the filling direction.

Regarding the rice in the upper and lower parts of the example and comparative example, grain texture (feeling that the grains can be recognized), plumpness (softness in the center of the rice), stickiness (softness in the center of the rice), hardness, Regarding desirability, freshly cooked rice within 1 hour after cooking was given a score of 5, and evaluation was made from 1 to 5 points using this as a standard. The evaluation criteria are shown in Table 2.

[evaluation]
The average value of the evaluations of 100 panelists was calculated and evaluated based on the following criteria.
◎: 4 points ≦ average value ≦ 5 points ○: 3 points ≦ average value < 4 points △: 2 points ≦ average value < 3 points ×: 1 point ≦ average value < 2 points

<Measurement and evaluation method of moisture content of cooked rice at the bottom of the container>
Take out the cooked rice prepared in the above method, collect 2.0 g of rice grains from the bottom surface in the filling direction, and 2.0 g of freshly cooked rice cooked in the above method within 5 minutes after cooking, and heat and dry each. Using a moisture meter (MS-70, manufactured by A and D) in rapid mode, the sample plate temperature was 140°C and the measurement accuracy was MID. The mode and end condition were set to 0.10%/min, the moisture content was measured, and the amount of change in the moisture content of the stored cooked rice was determined using the following formula (1).

Moisture percentage change (bottom) = Moisture percentage measurement value (bottom) - Moisture percentage measurement value (freshly cooked)... (1)
When the moisture content of stored cooked rice is close to that of freshly cooked rice, the amount of change in moisture percentage is ≈0, and when the amount of change in moisture percentage is <0, the rice is drier and harder than freshly cooked rice. On the other hand, if the amount of change in moisture content is >0, there is too much moisture, resulting in sticky rice.

[evaluation]
Evaluation was made using the absolute value of the moisture content change amount. Note that "|amount of change in moisture content|" means the absolute value of the amount of change in moisture content.
◎: 0≦｜Moisture percentage change｜＜2
○: 2≦｜Moisture percentage change｜<3
△: 3≦｜Moisture percentage change｜<5
×: 5≦｜Moisture percentage change｜

<Evaluation method of heating unevenness>
Heating unevenness was evaluated by a method using iodine starch reaction.
A paste water was prepared by dissolving 50 g of starch paste in 150 g of tap water. 200 g of cooked rice prepared by the above cooked rice preparation method (1) was added to 40 g of this starch water and stirred well, so that the grains of cooked rice were uniformly coated with the starch water. 4.0 g of iodine solution was added dropwise to the mixture and stirred well until the entire cooked rice became uniformly purple in color. Fill 180g of the purple cooked rice prepared by the above method into a food storage container using the same method as the above-mentioned method for preparing cooked rice (2) and (3), and freeze it using the same method as for the above-mentioned method for preparing cooked rice (4). did. The frozen rice prepared by the above method was heated for 2 minutes and 30 seconds in the microwave oven set at an output of 500W.
The cooked rice prepared by the above method was taken out from the food storage container 1, the purple coloring reaction disappeared and the weight percentage of the white part was calculated using the formula (2) below, and this was determined as uneven heating. .
Heating unevenness = (Weight of white part of rice (g) / 180g) x 100... (2)

[evaluation]
The heating unevenness calculated by the above method was evaluated based on the following criteria.
◎: 75<uneven heating≦100
○: 50<uneven heating≦75
△: 25<uneven heating≦50
×: 0≦Heating unevenness≦25

<Starch adhesion degree>
An iodine solution diluted 30 times with tap water was dropped into the food storage container 1 after removing the cooked rice prepared by the above-mentioned method for preparing cooked rice, and the area that turned purple due to the iodine-starch reaction was measured. was measured by image analysis, and the ratio of the area where the color reaction occurred was calculated using the following formula (3), and this was defined as the degree of starch adhesion.
Starch adhesion degree = (colored area/bottom projected area) x 100...(3)

[evaluation]
The degree of starch adhesion calculated by the above method was evaluated based on the following criteria.
◎: 0≦Starch adhesion degree<25
○: 25≦starch adhesion degree<50
△: 50≦Starch adhesion degree<75
×: 75≦Starch adhesion degree≦100

<Ease of washing>
A sensory evaluation of the ease of cleaning food storage containers was conducted by 100 housewives in their 20s to 50s. After removing the cooked rice prepared using the above rice preparation method, a food storage container is soaked in a dishwashing sponge (3M, Scotch Brite ^TM Antibacterial Urethane Sponge S-21KS) with tap water and washed with dishwashing detergent (Asahi Kasei Homes). The ease of cleaning (how the sponge hits the inside of the container) after adding 3 drops of Frosh ^R Aloe Vera) to the inside of the container was similar to that of the example and comparative example, except that there were no irregularities on the bottom and wall surfaces. A similar test was performed on a storage container (the same as in Comparative Example 1), and a score of 5 was given, and this was used as a standard for evaluation on a scale of 1 to 5 points.

[evaluation]
The average value of the evaluations of 100 panelists was calculated and evaluated based on the following criteria.
◎: 4 points ≦ average value ≦ 5 points ○: 3 points ≦ average value < 4 points △: 2 points ≦ average value < 3 points ×: 1 point ≦ average value < 2 points

Details of each example and comparative example will be described below.
[Example 1]
In the above manufacturing method, the liquid flowing through the channel 31 installed in the side wall 3 stays in the recess 21 formed in the bottom 2 as a liquid reservoir, and the water vapor circulates between the channel 31 and the recess 21. A food storage container 1 was obtained in which the flow path 31 and the recess 21 were connected to each other so as to form a circulation retention section. Each size is as shown in Table 1.

The evaluation results are shown in Table 1. Good results were obtained regarding the taste of the cooked rice, the moisture content in the bottom 2 of the container 1, uneven heating, degree of starch adhesion, and ease of washing.

[Example 2]
A food storage container 1 having the same shape as in Example 1 was manufactured except that the depth H of the recess 21 in the bottom part 2 was 1.5 mm, and the results of the same evaluation as in Example 1 are shown in Table 1. show. Good results were obtained regarding the taste of the cooked rice, the moisture content in the bottom 2 of the container 1, uneven heating, degree of starch adhesion, and ease of washing.

[Example 3]
A food storage container having the same shape as in Example 1 was manufactured except that the depth H of the recess 21 in the bottom part 2 was 3.0 mm, and the same evaluation as in Example 1 was performed. The results are shown in Table 1. . Good results were obtained regarding the taste of the cooked rice, the moisture content in the bottom 2 of the container 1, uneven heating, degree of starch adhesion, and ease of washing.

[Example 4]
A food storage container having the same shape as in Example 1 was manufactured except that the depth H of the recess 21 in the bottom part 2 was 4.0 mm, and the same evaluation as in Example 1 was performed. The results are shown in Table 1. . Although the taste of the cooked rice, the moisture content in the bottom 2 of the container 1, and the heating unevenness were good, the depth of the recess 21 provided in the bottom 2 was deep, so the starch stains that got stuck in the bottom recess 21 were not good. Washing with a sponge was not suitable because it could not be removed sufficiently and the degree of starch adhesion and ease of washing were insufficient.

[Example 5]
A food storage container having the same shape as in Example 1 was manufactured except that the depth H of the recess 21 in the bottom part 2 was 0.5 mm, and the same evaluation as in Example 1 was performed. The results are shown in Table 1. . The cooked rice was heated unevenly, and the moisture content in the bottom 2 of the container 1 was high, resulting in sticky rice, which was unsuitable.

[Example 6]
The distance L between the vertices of the protrusions 22 on the bottom 2 is 0.5 mm, the depth H of the recess 21 on the bottom 2 is 1.5 mm, and the length of one side of the square of the vertices of the protrusions 22 on the bottom 2 Table 1 shows the results of manufacturing a food storage container having the same shape as in Example 1 except that the diameter was 0.2 mm, and performing the same evaluation as in Example 1. Although the taste of the cooked rice, the moisture content in the bottom 2 of the container 1, and the heating unevenness were good, the depth of the recess 21 provided in the bottom 2 was deep, so the starch stains that got stuck in the bottom recess 21 were not good. Washing with a sponge did not remove the starch completely, and the degree of starch adhesion and ease of cleaning were inadequate.

[Example 7]
The distance L between the vertices of the convex portions 22 on the bottom portion 2 is 1.0 mm, the depth of the bottom unevenness is 1.5 mm, and the length of one side of the square at the apex of the convex portions 22 on the bottom portion 2 is 0.5 mm. Table 1 shows the results of manufacturing a food storage container having the same shape as in Example 1 except for the above, and performing the same evaluation as in Example 1. Good results were obtained regarding the taste of the cooked rice, the moisture content in the bottom 2 of the container 1, uneven heating, degree of starch adhesion, and ease of washing.

[Example 8]
The distance L between the vertices of the protrusions 22 on the bottom 2 is 2.0 mm, the depth H of the recess 21 on the bottom 2 is 2.0 mm, and the length of one side of the square of the vertices of the protrusions 22 on the bottom 2 Table 1 shows the results of manufacturing a food storage container having the same shape as in Example 1 except that the diameter was 1.0 mm, and performing the same evaluation as in Example 1. Good results were obtained regarding the taste of the cooked rice, the moisture content in the bottom 2 of the container 1, uneven heating, degree of starch adhesion, and ease of washing.

[Example 9]
A food storage container having the same shape as in Example 1 was manufactured, except that the distance L between the vertices of the convex portions 22 in the bottom portion 2 was 5.0 mm, and the depth H of the concave portions 21 in the bottom portion 2 was 1.5 mm. Table 1 shows the results of the same evaluation as in Example 1. Good results were obtained regarding the taste of the cooked rice, the moisture content in the bottom 2 of the container 1, uneven heating, degree of starch adhesion, and ease of washing.

[Example 10]
A food storage container having the same shape as in Example 1 was manufactured, except that the distance L between the vertices of the convex portions 22 in the bottom portion 2 was 9.0 mm, and the depth H of the concave portions 21 in the bottom portion 2 was 1.5 mm. Table 1 shows the results of the same evaluation as in Example 1. Good results were obtained regarding the taste of the cooked rice, the moisture content in the bottom 2 of the container 1, uneven heating, degree of starch adhesion, and ease of washing.

[Example 11]
A food storage container having the same shape as in Example 1 was manufactured, except that the distance L between the vertices of the convex portions 22 in the bottom portion 2 was 10.0 mm, and the depth H of the concave portions 21 in the bottom portion 2 was 1.5 mm. The same evaluation as in Example 1 was performed. The rice grains fit into the recesses installed on the bottom, and the cooked rice is completely attached to the bottom of the container, which affects the taste of the rice, the moisture content in the bottom 2 of the container 1, uneven heating, degree of starch adhesion, and ease of washing. It was unsuitable for all items.

[Example 12]
A food storage container 1 having the same shape as Example 1 except that the shape of the recess 21 and the protrusion 22 in the bottom part 2 is hemispherical, and the radius of the hemispherical protrusion 22 in plan view is 1.5 mm. was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1. Good results were obtained regarding the taste of the cooked rice, the moisture content in the bottom 2 of the container 1, uneven heating, degree of starch adhesion, and ease of washing.

[Example 13]
The shape of the concave portion 21 and the convex portion 22 in the bottom portion 2 is hemispherical, the radius of the hemispherical convex portion 22 in plan view is 1.15 mm, and the depth H of the concave portion 21 in the bottom portion 2 is 0.7 mm. A food storage container 1 having the same shape as in Example 1 except for this was manufactured and evaluated in the same manner as in Example 1. The results are shown in Table 1. Good results were obtained regarding the taste of the cooked rice, the moisture content in the bottom 2 of the container 1, uneven heating, degree of starch adhesion, and ease of washing.

[Comparative example 1]
A food storage container similar to that of Example 1 was manufactured except that the bottom portion 2 and side wall portion 3 had no irregularities and were flat, and the results were evaluated in the same manner as in Example 1. Table 1 shows the results. . Although the ease of cleaning with a sponge was highly evaluated, the cooked rice was heated unevenly and the moisture content in the bottom 2 of the container 1 was high, resulting in sticky cooked rice, which was unsuitable.

[Comparative example 2]
As shown in FIG. 19, a flat surface 5 having a smooth surface is interposed at the boundary between the flow path 31 provided in the side wall 3, the ridge 32, and the concave portion 21 and the convex portion 22 in the bottom portion 2. A food storage container having the same shape as in Example 1 except that the concave portion 21 was not connected was manufactured, and the same evaluation as in Example 1 was performed. Table 1 shows the results. Although the moisture content in the bottom 2 of the container 1 was good, the taste and uneven heating of the cooked rice were unsuitable.

1 Food storage container 2 Bottom part 21 Recessed part 22 Convex part 3 Side wall part 31 Channel 32 Ridge part 4 Flange part 5 Plane part

Claims (6)

A container for storing cooked rice consisting of a bottom part, a side wall part and a flange part and having an open top,
A gas or liquid flow path is formed in the side wall part in a vertical direction from the lower end of the flange part, curves in an R shape along the shape of the side wall part, and then heads horizontally until it reaches the bottom part . Multiple formations are formed within the range of
The bottom portion includes a concave portion and a convex portion,
The liquid flowing through the flow path heads toward the recess and stays in the recess, and the gas flowing through the flow path heads from the flow path toward the recess and flows into the recess, forming a circulating retention section, and the flow The channel and the recess are connected as a flow channel without any other structure intervening between them,
The convex portion is not formed when the flow path is traced from the flange toward the bottom , even when the flow path and the recess are filled with cooked rice to a uniform thickness. A container for storing cooked rice connected as a flow path. The cooked rice storage container according to claim 1, wherein the flow path is in the shape of a groove formed toward the bottom. The cooked rice storage container according to claim 2, wherein the distance between the vertices of the convex portions adjacent to each other is 1 to 9 mm. The cooked rice storage container according to claim 3, wherein the depth of the recess is 0.7 to 3 mm. 5. The container for storing cooked rice according to claim 3, wherein the volume of the recess space formed by the recess is 1 to 25 cm 3 per 100 cm 2 of the projected area of the bottom. The container for storing cooked rice according to any one of claims 3 to 5, wherein the surface area of the bottom is 1.5 times or more the projected area of the bottom.