JP2025027479A - Manufacturing method of packaged cooked rice, and packaged cooked rice - Google Patents

Abstract

To provide packaged cooked rice in which stored cooked rice has extremely small hard rice texture as a whole and cooked rice is easily separated from a storage container.SOLUTION: Packaged cooked rice is produced by a method including: an oil and fat coating step of spraying or applying edible oil and fat on an inner surface of a storage area in a storage container having heat resistance and coating the edible oil and fat so that the amount is more than 0 g/cm2 and equal to less than 0.008 g/cm2 with respect to the inner surface; a filling step of filling soaked rice which is soaked and drained and water in the storage area of the storage container in which edible oil and fat is coated so that soaked rice is 1.3 to 2.0 pts.mass with respect to 1.0 pt.mass of water; a heating step of heating soaked rice for 5 minutes to 30 minutes inside the storage area by steam above 95°C after the filling step; and a sealing step of sealing the storage area while a product temperature inside the storage area is equal to or more than 70°C after the heating step.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing packaged cooked rice, and packaged cooked rice.

Packaged cooked rice, in which cooked rice is contained and sealed, is highly convenient as it can be heated in a microwave oven or the like and eaten as is, or can be used to easily make a cooked rice food. Such packaged cooked rice is produced, for example, by filling a container with cooked rice that has been subjected to a rice cooking process and sealing it.

However, because the surface of cooked rice is highly viscous, adhesion losses are likely to occur when the rice is packed into a container, making it difficult to stabilize the packed weight. Problems such as increased production losses are also likely to occur. For this reason, a manufacturing method has been developed in which soaked rice is packed into a container, water is added, and the rice is heated and cooked while still in the container.

For example, Patent Document 1 discloses a method for producing containerized, aseptically cooked rice in which rice that has been washed in water, soaked in water, and drained is placed in a container with cooking water whose pH has been adjusted with an organic acid in a specified ratio, the rice is cooked under pressure and heat, and the container is then sealed.

JP 2001-224321 A

However, when soaked rice is heat-treated in a container, uneven heating tends to occur, and some of the rice tends to have a core-like texture (the texture of rice grains with a core). And when the heat treatment conditions are adjusted to ensure that the cooked rice in the container has very little core-like texture overall, the resulting cooked rice tends to stick more tightly to the container, making it difficult to separate (the rice grains are difficult to separate). In other words, it is quite difficult to achieve both of these goals at the same time.

Therefore, the present invention aims to provide packaged cooked rice in which the cooked rice contained therein has very little hard-rice texture overall, and in which the cooked rice can be easily separated from the container.

In order to solve the above problems, the present inventors conducted extensive research and found that a packaged cooked rice can be produced in which the cooked rice contained therein has very ^little hard-like texture overall and is easy to separate from the container by using a manufacturing method that includes: an oil-and-fat coating step of spraying or applying edible oil to the inner surface of a storage area in a heat-resistant storage container so that the amount of edible oil is more ^than 0 g/cm2 and not more than 0.008 g/cm2 of the inner surface; a filling step of filling the storage area of the storage container coated with edible oil with soaked rice that has been soaked and drained and water so that the amount of soaked rice is 1.3 to 2.0 parts by mass per 1.0 part by mass of water; a heat treatment step of heat-treating the soaked rice inside the storage area with steam at 95°C or higher for 5 to 30 minutes after the filling step; and a sealing step of sealing the storage area while the product temperature inside the storage area is 70°C or higher after the heat treatment step, thereby completing the present invention.

That is, the present invention relates to the following <1> to <8>.
<1> A method for producing packaged cooked rice in which cooked rice is contained and sealed in a heat-resistant storage container, the method comprising the steps of: spraying or applying edible oil or fat onto an inner surface of a storage area in the storage container so that the amount of the edible oil or fat is more than 0 g/ ^cm2 and not more than 0.008 g/ ^cm2 relative to the inner surface; filling a storage area of the storage container coated with the edible oil or fat with soaked rice that has been soaked and drained and water so that the amount of the soaked rice is 1.3 parts by mass to 2.0 parts by mass per 1.0 part by mass of the water; after the filling step, a heat treatment step of heat-treating the soaked rice inside the storage area with steam at 95°C or higher for 5 minutes to 30 minutes; and after the heat treatment step, sealing the storage area while the product temperature inside the storage area is 70°C or higher.
<2> The method for producing packaged cooked rice described in <1>, wherein the heat treatment step is a step of heat treatment using steam at 105°C or higher and 120°C or lower.
<3> The method for producing packaged cooked rice described in <1> or <2>, wherein the sealing step is a step of sealing the storage area in a clean booth having a cleanliness class of 10,000 or less.
<4> The method for producing packaged cooked rice described in any one of <1> to <3>, wherein the sealing step is a step of replacing the inside of the storage area with nitrogen gas and sealing the storage area.
<5> Further, after the sealing step, a cooling step is provided for cooling the product temperature inside the sealed storage area in the storage container to 20 ° C. or less. The method for producing packaged cooked rice described in any one of <1> to <4>.
<6> The method for producing packaged cooked rice according to any one of <1> to <5>, wherein the soaked rice packed in the packing step is soaked rice containing glutinous rice.
<7> A method for producing packaged cooked rice described in any one of <1> to <6>, wherein the storage area of the storage container is formed by connecting a plurality of storage recesses.
<8> Packaged cooked rice in which cooked rice is contained and sealed in a heat-resistant storage container, wherein edible oils and fats are adhered to a portion of the cooked rice, and the total amount of edible oils and fats adhered to the cooked rice in contact with the inner surface of the storage area of the storage container is greater than the total amount of edible oils and fats adhered to the cooked rice not in contact with the inner surface of the storage area of the storage container.

The present invention provides packaged cooked rice in which the cooked rice contained therein has very little hard-rice texture overall, and the cooked rice is easy to separate from the container.

1 is a process diagram showing an example of a method for producing packaged cooked rice according to the present invention. FIG. 2 is a perspective view of an example of a storage container (tray container) used in the manufacturing method of packaged cooked rice according to the present invention. 1 is a graph showing the change in product temperature over time of heat-treated rice in a tray container, measured in Example 1.

The present invention will now be described.
The present invention relates to a method for preparing a food-based food product by spraying or applying edible oil or fat onto an inner surface of a storage area of a heat-resistant storage container, and the amount of the edible oil or fat is ^more than 0 g/cm2 and less than 0.008 g/cm2 relative to the inner surface. a filling step of filling the storage area of the storage container coated with the edible oil with soaked rice that has been soaked and drained and water so that the amount of soaked rice is 1.3 to ^2.0 parts by mass per 1.0 part by mass of water, a heat treatment step of heat-treating the soaked rice inside the storage area with steam at 95°C or higher for 5 to 30 minutes after the filling step, and a sealing step of sealing the storage area while the product temperature inside the storage area is 70°C or higher after the heat treatment step; and packaged cooked rice in which edible oil is adhered to a part of cooked rice that is stored and sealed in a heat-resistant storage container, and in which the total amount of edible oil adhered to the cooked rice that is in contact with the storage area of the storage container is greater than the total amount of edible oil adhered to the cooked rice that is not in contact with the storage area of the storage container. Hereinafter, these may be referred to as "the method for producing packaged rice according to the present invention" and "packaged rice according to the present invention."
As an example of the method for producing packaged cooked rice according to the present invention, an example of the production process is shown in FIG.

First, we will explain in detail each step of the manufacturing method for packaged cooked rice according to the present invention.

<Oil and fat coating process>
In the method for producing packaged cooked rice according to the present invention, first, a container is prepared for storing and sealingly packaging the cooked rice. This container needs to be heat-resistant so that the soaked rice can be heated with steam in the container in the heat treatment step described below.
Here, "having heat resistance" means that the container has heat resistance to water vapor of 95°C or higher used in the heat treatment as described above, and does not deform, dissolve, or break due to temperature in this water vapor atmosphere. For example, a container having heat resistance to water vapor of 95 to 120°C is preferable.

The shape of the container is not particularly limited as long as it has a storage area capable of storing cooked rice (soaked rice and water before heat treatment), but examples include a tray container having a concave storage area with an opening on the top side of the container (the top side when the container is placed on the placement surface). In particular, it is more preferable that the storage area is a shape formed by connecting multiple storage recesses. For example, as shown in FIG. 2, it is preferable that the storage area 11 is a shape formed by connecting two or more concave storage recesses 15 (such as a bale-shaped storage recess 15 with an opening on the top side of the container) via a connecting part 17. By using a container having a storage area formed by connecting multiple storage recesses, the surface area of the bottom side of the container is larger in the heat treatment process described below, improving the heat exchange efficiency in this heat treatment process, and heat is easily transmitted to the center of the rice grains of the entire soaked rice contained therein, including the bottom side of the container, making it easier to heat the entire rice evenly. In this shape, as shown in FIG. 2, the connecting portion 17, which is the portion where the multiple storage recesses 15 are connected, may also be capable of storing soaked rice, etc., or the shape of the connecting portion may be such that the storage area is unified but the stored soaked rice, etc. is divided into individual storage recesses.

The material of the storage container is not particularly limited as long as it has the heat resistance described above, but a storage container made of resin is preferable because it is easy to design the shape and to seal the container by heat sealing using a resin film or the like. Specific examples include storage containers made of polypropylene resin, polyamide resin, polyethylene resin, etc. (i.e., made of a resin material containing more than 50 mass% of any of these as the main raw material). In particular, a storage container made of polypropylene resin is more preferable.

In the oil-and-fat coating process, edible oil is sprayed or applied to the inner surface (the surface that can come into direct contact with rice) of the storage area in the storage container (a storage container in a state where the contents such as soaked rice are not stored) so that the amount of the edible oil is more than 0 g/ ^cm2 and 0.008 g/ ^cm2 or less relative to the inner surface. This makes it possible to produce packaged cooked rice that is easy to separate from the storage container in the cooked rice state. In addition, when soaked rice is heat-treated with steam in an open container, there is a tendency for uneven heating to occur, especially on the opening side and the bottom side of the container. However, by combining this oil-and-fat coating process with a predetermined sealing process described later, even if a method of heat-treating soaked rice with steam in such a container is adopted, the above-mentioned uneven heating is unlikely to occur, and the core-rice feeling of the cooked rice near the inner surface of the bottom side of the container is easily reduced. In addition, the separability from the storage container is also maintained to a high degree. Furthermore, these effects are more easily obtained when the oil-and-fat coating is performed using a storage container having a storage area formed by connecting a plurality of storage recesses as described above.
The edible oil is not limited as long as it is an edible oil that can be sprayed or applied to coat the inner surface of the storage area, but is preferably an edible oil that is liquid at room temperature (5 to 35°C), and more preferably an edible vegetable oil that is liquid at room temperature. In particular, rapeseed oil, rice oil, sunflower oil, safflower oil, soybean oil, etc. are suitable because they have less effect on the flavor, etc. However, it is also possible to use edible animal oils and fats that have fluidity at room temperature, and it is also possible to melt and use edible oils and fats that are solid at room temperature.

As described above, the amount of the edible oil/fat coated on the inner surface of the storage area is set to be more than 0 g/ ^cm2 and 0.008 g/cm2 or ^less , but since this makes it easier to exhibit the effect of improving separation from the storage container and the effect of reducing the core-rice texture of the cooked rice near the inner surface in combination with the sealing process, the lower limit is more preferably 0.001 g/ ^cm2 or more, even more preferably 0.002 g/ ^cm2 or more, even more preferably 0.003 g/ ^cm2 or more, and even more preferably 0.004 g/ ^cm2 or ^more . From the viewpoint of maintaining the taste, texture, etc. of the stored cooked rice to a high degree, the upper limit is more preferably 0.007 g/cm2 or less, and even more preferably 0.006 g/ ^cm2 or less.
Here, the oil coating is applied to substantially the entire inner surface of the storage area, but it is not necessary to apply oil coating to surfaces other than the inner surface of the storage area. For example, when heat sealing is performed in the sealing step described below, it is preferable that the surface of the portion used for this heat sealing (such as the flange portion 13 shown in Figure 2) is not coated with oil.

In the method for producing packaged cooked rice according to the present invention, it is extremely important to carry out an oil-and-fat coating process in which a predetermined amount of edible oil is coated on the inner surface of the storage area of the storage container in order to obtain packaged cooked rice in which the cooked rice is easily separated from the storage container. In other words, if this oil-and-fat coating process is not carried out, the above-mentioned effect will not be fully achieved even if edible oil is added to the water during soaking or edible oil is simply filled into the storage area together with the soaked rice and water. In addition, as described above, this oil-and-fat coating process, when combined with a predetermined sealing process, also has the effect of easily reducing the hard-rice feel of the cooked rice near the inner surface of the storage area that has undergone a predetermined heat treatment process in which the soaked rice is heat-treated with steam in an open container.

<Filling process>
Next, in the manufacturing method for packaged cooked rice according to the present invention, a filling step is carried out in which soaked rice that has been soaked and drained and water are filled into a storage area of a storage container having an inner surface coated with oil or grease, so that the amount of soaked rice is 1.3 to 2.0 parts by mass per 1.0 part by mass of water.

The raw rice used for the soaked rice packed in this packing step can be unpolished rice, glutinous rice, polished rice, no-rinse rice, etc., and there is no particular limitation on the type of rice. Also, so-called foreign rice such as indica rice can be used as the raw rice. Note that the method for producing packaged cooked rice according to the present invention is characterized in that the effect of the present invention can be exhibited even when the soaked rice packed in this packing step is soaked rice containing glutinous rice (soaked rice containing 100% glutinous rice, or soaked rice containing a mixture of glutinous rice and rice other than glutinous rice such as glutinous rice).
Here, brown rice refers to rice from which the husk has been removed and from which the germ, pericarp, seed coat and aleurone layer (so-called rice bran) have not been removed, and also includes germinated brown rice obtained by germinating this rice. Polished rice refers to rice from which the germ, pericarp, seed coat and aleurone layer have been removed by polishing, and no-rinse rice refers to rice from which the bran (sticky rice bran) remaining on the surface of the rice grain has been removed from the polished rice.

In the manufacturing method for packaged cooked rice according to the present invention, a soaking process is carried out as a preparatory process for the filling process, in which the raw material rice as described above is soaked in water for a certain period of time to obtain soaked rice that has absorbed water, but if necessary, a rice washing process may be carried out to wash the raw material rice, and the rice washed in this rice washing process may be soaked. Furthermore, the washed rice may be further mixed with raw material rice such as no-wash rice and soaked. The rice washing process is a process in which bran and dirt on the surface of the raw material rice are washed away with water to remove them, and the raw material rice may be washed using water at room temperature (5 to 35°C) by a known method.
In the soaking process, the above-mentioned rice (washed rice, etc.) can be soaked in water at room temperature for about 10 to 150 minutes to obtain soaked rice. Natural coloring matter, pH adjusters, antioxidants, etc. may be added to the water used in this soaking process. The liquid is then drained (solid-liquid separation) and the rice is filled into the storage area of the storage container. The mass of the soaked rice after draining is not limited, but is preferably about 110 to 150% by mass of the mass of the raw rice (rice before washing and soaking).

The soaked rice and water obtained as described above can be filled into a storage container by a known method. For example, the soaked rice can be filled using a measuring cup, and the water can be filled using a nozzle that can measure and discharge water and is connected to a pipe or the like. The soaked rice is filled into the storage area of the storage container so that the amount of soaked rice is 1.3 parts by mass or more and 2.0 parts by mass or less per 1.0 part by mass of water. The mass of the soaked rice is more preferably 1.5 parts by mass or more and more preferably 1.8 parts by mass or less per 1.0 part by mass of water.
In this filling step, other ingredients (for example, seasonings, ingredients, miscellaneous grains, etc.) may also be filled together, but the effects of the present invention are more likely to be achieved when only soaked rice and water are filled in this filling step.

<Heat treatment step>
Next, in the method for producing packaged cooked rice according to the present invention, after the filling step described above, a heat treatment step is performed in which the soaked rice is heat-treated for 5 to 30 minutes inside the unsealed storage area using steam at 95°C or higher (under a steam atmosphere). In other words, a predetermined heat treatment is performed in a state in which the steam can directly contact the soaked rice or water in the container. The temperature of this steam is preferably 98°C or higher, more preferably over 100°C (superheated steam), and even more preferably 105°C or higher. In addition, the heat treatment time (time to expose to a steam atmosphere at a predetermined temperature) is preferably 8 minutes or more, more preferably 10 minutes or more, and even more preferably 12 minutes or more. The upper limit is preferably 25 minutes or less, more preferably 20 minutes or less, and even more preferably 15 minutes or less.
For example, this heat treatment step is more preferably a step of heat treatment with steam at 95° C. to 120° C., and even more preferably a step of heat treatment with steam (superheated steam) at 105° C. to 120° C. This is because direct heat treatment with such superheated steam further improves the heat exchange efficiency, and the quality of the resulting cooked rice is likely to be improved.

In the manufacturing method of packaged cooked rice according to the present invention, a heat treatment with water vapor is used to heat the soaked rice in the container, and by combining it with other processes (a specific oil coating process and a sealing process), the effect of the present invention is achieved, which is to bring the entire cooked rice, including the area near the inner surface of the storage area, to a moderately cooked state, reduce the feeling of hard rice, and improve separation from the storage container (achieving both of these simultaneously), but this effect may not be achieved if other heat processes are used.

<Sealing process>
Next, in the manufacturing method of packaged cooked rice according to the present invention, after the above-mentioned heat treatment process, a sealing process is carried out to seal the storage area while the product temperature inside the storage area (the product temperature of the heat-treated rice) is 70°C or higher.
This sealing step may be performed by sealing airtightly so that the heat-treated rice cannot come into direct contact with the outside air (gas outside the container), and the means for this may be, for example, a method of covering flange portion 13 with a resin film (such as a laminate film made of polyolefin resin) so as to cover the opening of storage area 11 in the tray container shown in Fig. 2, and then heat sealing this film to flange portion 13 at flange portion 13. The conditions for this heat sealing may be appropriately designed depending on the material of the film and storage container used, and examples include conditions for sealing (pressing) at 95°C to 110°C for 0.5 to 3 seconds.

In this sealing step, it is necessary to seal the storage area while the product temperature inside the storage area (the product temperature of the heat-treated rice) is 70°C or higher (hot seal). As a result, after sealing, the heat-treated rice undergoes a gradual temperature drop in the sealed storage area, and the product temperature can be maintained at or above the gelatinization starting temperature of rice starch (61°C) for a relatively long time, which allows the gelatinization of the rice grains, including the core of the rice grains and the rice grains close to the inner surface of the bottom side of the container in the storage area, to proceed moderately, achieving uniform gelatinization and uniform moisture content, and in combination with the effect of the oil coating step described above, the overall texture of the resulting cooked rice is excellent. For this reason, there is no need to excessively increase the heat treatment conditions in the heat treatment step in order to make the cooked rice contained therein have an extremely low core rice feel overall. Therefore, including the effect of the oil coating step described above, the separability from the storage container is also highly maintained. In addition, this hot sealing makes it easy to obtain the effect of suppressing microbial contamination of packaged cooked rice (the effect of improving shelf life) even if ingredients that improve shelf life (e.g., glycine, pH adjusters, etc.) are not used, that is, even if such ingredients are substantially not contained.
In addition, since the product temperature inside the storage area at the time of sealing is more likely to exhibit the above-mentioned effects, it is more preferable that it is 75°C or higher, even more preferable that it is 80°C or higher, even more preferable that it is 85°C or higher, even more preferable that it is 90°C or higher, and even more preferable that it is 95°C or higher.

In addition, this sealing step is preferably a step of sealing the storage area in a clean booth having a cleanliness level of class 10,000 or less, more preferably in a clean booth having a cleanliness level of class 1,000 or less, and even more preferably in a clean booth having a cleanliness level of class 100 or less. This is because the synergistic effect with the above-mentioned hot seal makes it easier to obtain the effect of suppressing microbial contamination of the packaged cooked rice (the effect of improving the shelf life).
Here, "cleanliness of Class 10,000 or less" refers to a cleanliness level based on the FED (Federal Standards) standard, and means a cleanliness level where the number of particles with a diameter of 0.5 μm or more contained in the air per cubic foot is 10,000 or less. The same is true for "cleanliness of Class 1000 or less" and "cleanliness of Class 100 or less."

Furthermore, this sealing process is preferably a process of replacing the inside of the storage area with nitrogen gas and sealing the storage area (gas replacement packaging, MAP packaging). In other words, it is preferably a process of sealing the storage area in an atmosphere replaced with nitrogen gas after vacuum processing or the like, or a process of replacing the air inside the storage area with nitrogen gas and sealing the storage area at the same time. This is because the synergistic effect with the hot seal described above makes it easier to obtain the effect of suppressing microbial contamination of the packaged cooked rice, and also makes it easier to maintain the quality of the cooked rice (especially the aroma) at a high level.

The method for producing packaged cooked rice according to the present invention includes the oil coating step, filling step, heat treatment step, and sealing step as described above, and may further include a cooling step after the sealing step in which the product temperature inside the sealed storage area in the storage container (the product temperature of the heat-treated rice) is cooled to 20° C. or lower. This cooling can be performed by a method of storing the product at an ambient temperature of 20° C. or lower.
In the case of a chilled product, the cooling temperature may be 15° C. or lower, less than 10° C., or 5° C. or lower. In the case of a frozen product, the cooling temperature may be less than 0° C., −5° C. or lower, −10° C. or lower, −15° C. or lower, or −20° C. or lower.

Furthermore, the method for producing packaged cooked rice according to the present invention may include any other process as long as it does not significantly affect the effects of the present invention. For example, depending on the temperature range for distribution, a sterilization process using ultraviolet light or the like may be included. However, when producing packaged cooked rice to be distributed and sold at a temperature below 10°C (including freezing), or when the shelf life at the distribution temperature range can be guaranteed without carrying out a special sterilization process, such a sterilization process may be omitted.
As described above, as an example of the method for producing packaged cooked rice according to the present invention, an example of a process for producing packaged cooked rice is shown in FIG. 1, which includes the steps of preparing a heat-resistant storage container, coating the storage area of the storage container with a specified oil or grease, filling the storage area with a specified amount of soaked rice and water, carrying out a specified heat treatment using a specified amount of water vapor within the storage area, sealing with a specified hot seal in a clean booth, and then cooling.

The packaged cooked rice produced by the method for producing packaged cooked rice according to the present invention as described above has very little hard-rice texture throughout the cooked rice, and the cooked rice is easy to separate from the container (easy to separate). The cooked rice throughout the entire container area is thoroughly cooked and has an excellent texture.

Next, we will explain in detail the packaged cooked rice of the present invention.

The packaged cooked rice of the present invention is packaged cooked rice in a heat-resistant container that is sealed with cooked rice, and is characterized in that edible oils and fats are attached to a portion of the cooked rice, and that the total amount of edible oils and fats attached to the cooked rice (rice grains) that are in contact with the inner surface of the container's storage area is greater than the total amount of edible oils and fats attached to the cooked rice (rice grains) that are not in contact with the inner surface of the container's storage area. Due to these characteristics, the cooked rice stored has very little core-like texture overall (the texture of the cooked rice is excellent throughout the storage area), and is packaged cooked rice that is easy to separate from the container. Packaged cooked rice of the present invention having these characteristics can be manufactured by the above-mentioned method for manufacturing packaged cooked rice according to the present invention.

Here, the heat-resistant container has the same meaning as described above. The total amount of edible oils and fats attached to the cooked rice (rice grains) in contact with the inner surface of the container's storage area is the total amount of edible oils and fats attached to all cooked rice grains in contact with this inner surface, and can be measured by separating and collecting all rice grains in contact with the inner surface and conducting an oil analysis (Soxhlet extraction, etc.). The total amount of edible oils and fats attached to the cooked rice (rice grains) not in contact with the inner surface of the container's storage area is the total amount of edible oils and fats attached to all cooked rice grains not in contact with this inner surface, and can also be measured by separating and collecting all rice grains not in contact with the inner surface and conducting an oil analysis. These "attached" amounts also include some edible oils and fats that have penetrated into the rice grains after attachment. Furthermore, the edible oils and fats may be the same as described above.

In addition, the packaged cooked rice of the present invention may contain any additive components, etc., as long as the above-mentioned configuration is satisfied and the effect of the present invention is not significantly affected by the packaged cooked rice sealed in a container. For example, seasoning components, ingredients, miscellaneous grains, etc. may be included. However, the effect of the present invention is more likely to be achieved when only the cooked rice and edible oils and fats are sealed (when the raw materials are only rice, water, and edible oils and fats). In addition, the distribution temperature range is not particularly limited, and the packaged cooked rice may be distributed and sold at a temperature of 20°C or less, or even less than 10°C.
Furthermore, it is more preferable that the packaged cooked rice of the present invention is packaged cooked rice in which cooked rice is contained and sealed in a storage area of a tray container (a resin tray container having a storage area formed by connecting a plurality of storage recesses) as shown in Figure 2.

The following describes examples of the present invention, but the present invention is not limited to the following examples, and various modifications are possible within the technical concept of the present invention.

Example 1
Two tray containers (made of polypropylene, manufactured by Hirokawa Co., Ltd.) having the shape shown in FIG. 2 were prepared, and vegetable oil (edible rapeseed oil) was applied (coated) to the inner surface of the storage area so that the amount of the oil was 0.005 g/ ^cm2 of the inner surface. Then, the storage area was filled with soaked rice (non-sticky rice, the mass of the raw rice was about 120% by mass) that had been soaked and drained, and water so that the soaked rice was 1.73 parts by mass per 1.0 part by mass of water, and these were each heat-treated for 12.5 minutes inside the storage area with superheated steam at 105°C. Furthermore, for one sample, immediately after this heat treatment (the product temperature of the heat-treated rice in the storage area was 95°C), a laminate film (manufactured by NASCO Co., Ltd.) made of polyolefin resin was heat-sealed (top-sealed) to the flange portion to seal the storage area (sample 1: with film, product temperature inside the storage area can be measured). The other sample was not sealed with film, leaving the containment area open (Sample 2: no film).

These samples were then stored stationary in an atmosphere of 25°C, and the product temperature inside the storage area (the product temperature of the heat-treated rice) was measured every 5 minutes starting immediately after the heat treatment (0 minutes). The results are shown in Table 1 (top row: sample 1, bottom row: sample 2) and Figure 3 (circles: sample 1, triangles: sample 2) below.

These results show that by sealing the storage area immediately after heat treatment (when the product temperature of the heat-treated rice is 95°C), the time during which the product temperature inside the storage area is maintained at 61°C (the gelatinization temperature of rice starch) or higher can be extended by approximately 8 minutes compared to when the storage area is not sealed.

Example 2
Three tray containers (made of polypropylene, manufactured by Hirokawa Co., Ltd.) having the shape shown in Fig. 2 were prepared, and vegetable oil (edible rapeseed oil) was applied (coated) to the inner surfaces of the storage areas in the amounts shown in Table 2 below (Samples 4 to 6). One tray container (made of polypropylene, manufactured by Hirokawa Co., Ltd.) having the shape shown in Fig. 2 but not coated with oil was also prepared (Sample 3), and the storage areas were filled with soaked rice (non-glutinous rice, the mass of the raw rice was about 120% by mass) that had been soaked and drained, and water, so that the soaked rice was 1.73 parts by mass per 1.0 part by mass of water, and these were each heated for 12.5 minutes inside the storage areas using superheated steam at 105°C. Furthermore, immediately after this heat treatment (the product temperature of the heat-treated rice in the storage area was 95°C), a laminate film (product of NASCO Corporation) made of polyolefin resin was heat-sealed to the flange portion in a clean booth with a cleanliness level of Class 1000 or less to seal the storage area.

Then, after these samples were cooled to 20°C or less and the product temperature stabilized, 10 trained panelists with discernment abilities checked the presence or absence of cooked rice on the bottom of the storage area (ease of separation from the tray container) and the quality of cooked rice near the bottom of the storage area (appearance and texture). Based on these, a comprehensive evaluation was also conducted by scoring the samples according to the following criteria (absolute evaluation).
5: Good 4: Generally good 3: Fair 2: Slightly poor 1: Poor

The results (amount of oil coating for each sample and evaluation results) are shown in Table 2 below.

From these results, sample 3, which does not have a fat coating on the storage area, had a good texture of cooked rice, but the cooked rice adhered to the bottom of the storage area, meaning that it was difficult to separate from the container. On the other hand, samples 4 to 6, which have a fat coating on the storage area, did not have cooked rice adhere to the bottom of the storage area, meaning that the cooked rice (cooked rice) was easy to separate from the container, and the quality of the cooked rice near the bottom of the storage area was generally good. In particular, samples 4 and 5, which have a fat coating amount of 0.003 g/cm ² or 0.005 g/cm ² on the storage area, did not have cooked rice adhere to the bottom of the storage area, and the quality of the cooked rice, including the area near the bottom of the storage area, was very good.

Example 3
Three tray containers (made of polypropylene, manufactured by Hirokawa Co., Ltd.) with the shape shown in Fig. 2 were prepared, and vegetable oil (edible rapeseed oil) was applied (coated) to the inner surface of the storage area so that the amount of the oil was 0.005 g/ ^cm2 of the inner surface. Then, soaked rice (non-glutinous rice, the mass of the raw material rice was about 120% by mass) that had been soaked and drained, and water were filled into these storage areas so that the soaked rice was 1.73 parts by mass per 1.0 part by mass of water, and these were each heat-treated for 12.5 minutes inside the storage area with superheated steam at 120°C. Furthermore, in a clean booth with a cleanliness level of class 1000 or less, while checking the product temperature inside the storage area after this heat treatment (the product temperature of the heat-treated rice), a laminate film (product of NASCO Corporation) made of polyolefin resin was heat-sealed to the flange portion to seal the storage area at a product temperature of 95°C (immediately after heat treatment, sample 9), 70°C (sample 8), or 65°C (sample 7).

After cooling these samples to 20°C or less and stabilizing the product temperature, the quality of the cooked rice (whether or not the rice still had a hard-rice texture and the overall taste and texture of the cooked rice) was checked by 10 trained panelists with the ability to discern. Based on this, the samples were also scored according to the following criteria (absolute evaluation) and an overall evaluation was performed.
5: Good 4: Generally good 3: Can be eaten 2: Slightly bad 1: Bad

The results (evaluation results for each sample) are shown in Table 3 below.

From this result and the result of Example 1 described above, it became clear that by sealing the package while the product temperature inside the storage area is at or above 70°C after the heat treatment, the gelatinization of the rice inside the storage area after sealing becomes more likely to proceed, and the amount of cooked rice remaining with a core-like texture is reduced, resulting in packaged cooked rice with improved taste and texture.

The above shows that the method for producing packaged cooked rice according to the present invention makes it possible to obtain packaged cooked rice that has very little hard-rice texture overall and that can be easily separated from the container.

100 Tray-shaped storage container 11 Storage area 13 Flange portion 15 Storage recess 17 Connection portion

Claims (8)

A method for producing packaged cooked rice in which cooked rice is contained and sealed in a heat-resistant container,
An oil/fat coating process in which edible oil is sprayed or applied to the inner surface of the storage area of the storage container so that the amount of the edible oil is more than 0 g/ ^cm2 and 0.008 g/ ^cm2 or less relative to the inner surface;
A filling step of filling the soaked rice that has been soaked and drained and water into the storage area of the storage container coated with the edible oil and fat such that the soaked rice is 1.3 parts by mass to 2.0 parts by mass per 1.0 part by mass of the water;
After the filling step, a heat treatment step of heat-treating the soaked rice in the storage area for 5 minutes to 30 minutes using steam at 95 ° C. or higher;
A sealing step of sealing the storage area while the product temperature inside the storage area is 70 ° C. or higher after the heat treatment step.
A method for manufacturing packaged cooked rice. The method for producing packaged cooked rice according to claim 1, wherein the heat treatment step is a step of heat treatment with steam at 105°C or higher and 120°C or lower. The method for producing packaged cooked rice according to claim 1 or 2, wherein the sealing step is a step of sealing the storage area in a clean booth having a cleanliness class of 10,000 or less. The method for producing packaged cooked rice according to claim 1 or 2, wherein the sealing step is a step of replacing the inside of the storage area with nitrogen gas and sealing the storage area. The method for producing packaged cooked rice according to claim 1 or 2 further includes a cooling step for cooling the product temperature inside the sealed storage area of the storage container to 20°C or lower after the sealing step. The method for producing packaged cooked rice according to claim 1 or 2, wherein the soaked rice packed in the packing step is soaked rice containing glutinous rice. The method for producing packaged cooked rice according to claim 1 or 2, wherein the storage area of the storage container is formed by connecting a plurality of storage recesses. A packaged cooked rice in which cooked rice is contained in a heat-resistant container and sealed,
Edible oils and fats are attached to a part of the cooked rice, and the total amount of the edible oils and fats attached to the cooked rice that is in contact with the inner surface of the storage area of the storage container is greater than the total amount of the edible oils and fats attached to the cooked rice that is not in contact with the inner surface of the storage area of the storage container.
Packaged cooked rice.

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