JP7156966B2 - Cooked rice production method - Google Patents

Description

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

In recent years, the demand for rice balls and boxed lunches displayed in convenience stores and supermarkets has increased, and the demand for boiled rice that is cooked in large quantities by manufacturers and kept at room temperature, refrigerated, or frozen for a relatively long time is also increasing. .

Conventionally, as a technology for producing cooked rice, steam treatment of uncooked rice is used to industrially produce boiled rice such as pilaf and fried rice that can be stored for a long time as frozen food and is suitable for microwave cooking. , Patent Document 1), a method for producing retort cooked rice having a crispy appearance and a crunchy texture suitable for Western-style cooked rice by steam-treating raw rice that has not been pretreated and retort-sterilizing it ( For example, see Patent Document 2), and a method for producing boiled rice in which the time required for the water absorption step is greatly reduced by exposing non-soaked raw rice to a superheated steam atmosphere while sprinkling water (see Patent Document 3, for example). , a method for producing retort porridge with improved quality by steaming uncooked rice for 10 to 240 seconds to suppress the occurrence of broken boiled rice and boiled rice that has collapsed (see, for example, Patent Document 4). is proposed.

However, these proposed techniques are intended for cooked rice with a low yield or for cooked rice with an excessively high yield, so the above-described large-scale rice cooking and holding at normal temperature, refrigerated, or frozen state for a relatively long time There is a problem that it is not suitable for the production of cooked rice.

The above-mentioned boiled rice that is cooked in large quantities and kept at room temperature, refrigerated, or frozen for a relatively long time is different from the boiled rice that is kept at a high temperature after cooking like at home. There is a problem that deterioration progresses. In addition, since these cooked rice may not be reheated when eaten, there is a particular demand for deterioration prevention technology in this respect as well.

For the purpose of preventing deterioration, it is conceivable to increase the yield of cooked rice by increasing the amount of water added during cooking.

Most of the above-mentioned cooked rice that is cooked in large quantities and kept at room temperature, refrigerated, or frozen for a relatively long time is manufactured through a molding process before distribution after cooking, but it can be cooked under normal rice cooking conditions. However, there is a problem that it tends to adhere to equipment such as machines in the molding process, and even if oils and fats are added to solve this problem, the current situation is that the moldability cannot be sufficiently improved.
Therefore, if the yield of boiled rice is increased in order to prevent deterioration, it is considered that the moldability will be further deteriorated.

Therefore, a method for producing cooked rice that can suppress deterioration of cooked rice and is excellent in moldability has not yet been provided, and prompt provision thereof is strongly desired.

JP-A-2001-333707 JP-A-6-303926 JP 2014-226062 A JP 2006-180737 A

An object of the present invention is to solve the above-mentioned conventional problems and to achieve the following objects. That is, it is an object of the present invention to provide a method for producing cooked rice that is not sticky even with a high yield and that suppresses deterioration.

As a result of intensive research conducted by the present inventors in order to achieve the above object, the method includes a steam treatment step of steaming uncooked rice that has not been immersed in water, and a rice cooking step of cooking rice after the steam treatment step. , By adopting a production method in which the mass of the cooked rice immediately after cooking is 250 parts by mass or more and 270 parts by mass or less per 100 parts by mass of uncooked rice, the cooked rice is not sticky even at a high yield and deterioration is suppressed. I found out that rice can be produced.

The present invention is based on the findings of the present inventors, and means for solving the above problems are as follows. Namely
<1> A steaming step of steaming uncooked rice that has not been immersed in water;
A rice cooking step of cooking rice after the steam treatment step,
A method for producing cooked rice, characterized in that the mass of the cooked rice immediately after cooking is 250 parts by mass or more and 270 parts by mass or less per 100 parts by mass of uncooked rice.
<2> The method for producing cooked rice according to <1>, wherein an increase in mass of the uncooked rice after the steam treatment is 10 parts by mass or less per 100 parts by mass of the uncooked rice.
<3> The method for producing cooked rice according to <1> or <2>, wherein the steam treatment is performed for 3 minutes or more and 60 minutes or less.
<4> The method for producing cooked rice according to any one of <1> to <3>, wherein the cooked rice is distributed at room temperature or refrigerated without being heat sterilized.
<5> The method for producing cooked rice according to any one of <1> to <4>, further comprising a molding step of molding the cooked rice.

According to the present invention, it is possible to solve the above-mentioned conventional problems, achieve the above-mentioned objects, and provide a method for producing cooked rice that is not sticky even with a high yield and that suppresses deterioration.

FIG. 1 is a graph showing the physical property measurement results of the cooked rice produced in Production Examples 1-1 to 1-6 and Comparative Production Example 1-1. FIG. 2A is an optical microscope photograph of the sample of Production Example 1-3 after 10 minutes of steam treatment, stained with eosin. FIG. 2B is an optical microscope photograph of the sample of Production Example 1-3 after being immersed in tap water for 1 hour and stained with eosin. FIG. 2C is an optical microscope photograph when the cooked rice produced in Production Example 1-3 was stained with eosin. FIG. 2D is an optical microscope photograph of the sample before immersion in tap water of Comparative Production Example 1-1, which was stained with eosin. FIG. 2E is an optical microscope photograph of the sample of Comparative Production Example 1-1 after being immersed in tap water for 1 hour and stained with eosin. FIG. 2F is an optical microscope photograph when the cooked rice produced in Comparative Production Example 1-1 was stained with eosin.

(Method for producing cooked rice)
The method for producing cooked rice of the present invention includes a steam treatment step of steaming uncooked rice that has not been immersed in water, and a rice cooking step of cooking the rice obtained in the steam treatment step, and further includes other steps. can contain.

<Steam treatment process>
The steaming step is a step of steaming uncooked rice that has not been immersed in water.
In the present invention, uncooked rice that has not been soaked in water means uncooked rice that has not been substantially watered, and does not include, for example, rice that has been immediately washed with water.

The uncooked rice is not particularly limited and can be appropriately selected depending on the intended purpose. Examples include polished rice, rinse-free rice, brown rice, half-milled rice, germ rice, and uncooked rice from which the bran has been removed by blowing. . These may be used individually by 1 type, and may use 2 or more types together. Among these, in the present invention, rinse-free rice or uncooked rice from which the bran or the like has been removed by air is preferable because it is not soaked in water before steam treatment, and rinse-free rice is more preferable in terms of quality.

The type of rice is not particularly limited and can be appropriately selected according to the purpose. Examples include non-glutinous rice, glutinous rice, or a combination thereof. non-glutinous rice and the like. These may be used individually by 1 type, and may use 2 or more types together. Among these, non-glutinous rice is preferable from the viewpoint of taste and moldability.

The variety of rice is not particularly limited and can be appropriately selected according to the purpose. Koshiibuki, Kinumusume, Tsugaru Roman, Yume Tsukushi, Tsuyahime, or combinations thereof. These may be used individually by 1 type, and may use 2 or more types together.

The type of steam treatment is not particularly limited as long as the steam treatment is not performed while sprinkling water, and can be appropriately selected according to the purpose. Examples include saturated steam treatment and superheated steam treatment.

The method of the saturated steam treatment is not particularly limited and can be appropriately selected according to the purpose.
The temperature of the saturated steam treatment is not particularly limited and can be appropriately selected according to the purpose. More preferably, the temperature is 90°C or higher.

The superheated steam treatment method is not particularly limited and can be appropriately selected depending on the intended purpose.
The temperature of the superheated steam treatment is not particularly limited and can be appropriately selected according to the purpose. is more preferable, and 100° C. or higher and 120° C. or lower is even more preferable.
The absolute humidity of the superheated steam treatment is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 350 g/m ³ or more and 550 g/m ³ or less.

The treatment time of the steam treatment is not particularly limited and can be appropriately selected according to the purpose. More preferred are:

The lower limit of the treatment time is preferably 3 minutes or longer, more preferably 5 minutes or longer, and even more preferably 10 minutes or longer, in order to prevent stickiness and deterioration.
The upper limit of the treatment time is preferably 60 minutes or less, more preferably 30 minutes or less, and even more preferably 20 minutes or less, from the viewpoint of preventing stickiness and deterioration. On the other hand, if the steaming time is too long, the rice grains will not adhere to each other because the stickiness will be too low, and the shape of the cooked rice after molding will become fragile, and the rice grains will become hard.

The amount of increase in the mass of the uncooked rice after the steam treatment is not particularly limited and can be appropriately selected according to the purpose. 10 parts by mass or less is preferable with respect to 100 parts by mass, and 5 parts by mass or more and 10 parts by mass or less is more preferable.

The time between the steam treatment step and the rice cooking step described later or the soaking step after the steam treatment described later is not particularly limited and can be appropriately selected according to the purpose, but is preferably within 24 hours. Within 12 hours is more preferable, within 1 hour is more preferable, and within 30 minutes is particularly preferable. If the time between the steam treatment step and the rice cooking step described later, or the soaking step after the steam treatment described later becomes longer, the surface of the steamed rice is aged again, and cracks are likely to occur during rice cooking, resulting in It tends to become sticky, and the machine aptitude may deteriorate. Moreover, the taste may also deteriorate.

<Rice cooking process>
The rice cooking step is a step of cooking rice after the steam treatment step.

The rice cooking method is not particularly limited as long as it is a method of cooking rice with water, and can be appropriately selected according to the purpose. A method including a cooking process and a steaming process can be mentioned, but any method commonly used as a rice cooking method or a known method can be employed. Moreover, both a rice cooking method using household rice cooking equipment and a rice cooking method using commercial rice cooking equipment can be adopted.

The cooker used for the rice cooking is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include a rice cooker and a rice cooker.

The amount of water to be added is not particularly limited and can be appropriately selected according to the purpose. Water can be added so that the content becomes 270 parts by mass or less.

The yield after cooking is not particularly limited as long as the mass of the cooked rice immediately after cooking is 250 parts by mass or more and 270 parts by mass or less with respect to 100 parts by mass of uncooked rice, and can be appropriately selected according to the purpose. However, from the viewpoint of taste, it is more preferably 250 parts by mass or more and 265 parts by mass or less, more preferably 250 parts by mass or more and 260 parts by mass or less per 100 parts by mass of uncooked rice. If it is less than 250 parts by mass per 100 parts by mass of uncooked rice, deterioration cannot be suppressed, and if it is more than 270 parts by mass per 100 parts by mass of uncooked rice, the taste and formability deteriorate.

<Other processes>
The other steps are not particularly limited and can be appropriately selected according to the purpose. Examples include a step of adding additives and the like.

<<Immersion process after steam treatment>>
The immersion step after the steam treatment is a step of immersing the rice after the steam treatment in water.

The immersion time is not particularly limited and can be appropriately selected according to the purpose, but is preferably 3 minutes or longer, more preferably 5 minutes or longer, and even more preferably 15 minutes or longer.

The immersion temperature is not particularly limited and can be appropriately selected according to the purpose, but is preferably 5°C or higher and 30°C or lower.

The amount of increase in mass after the immersion is not particularly limited and can be appropriately selected according to the purpose. It is more preferably 50 parts by mass or less, further preferably 30 parts by mass or more and 50 parts by mass or less, and particularly preferably 35 parts by mass or more and 50 parts by mass or less.

<<Cooling process after cooking>>
The cooling step after cooking is a step of cooling the cooked rice after cooking.
The cooling is not particularly limited and can be appropriately selected depending on the purpose.
The temperature after cooling is not particularly limited and can be appropriately selected according to the purpose, but from the viewpoint of hygiene, it is preferably 30° C. or less, more preferably 25° C. or less, and further preferably 20° C. or less. .

<<Molding process after cooking>>
The forming step after cooking is a step of forming the cooked rice after cooking.
The molding is not particularly limited and can be appropriately selected according to the purpose, and examples include molding using a mold, a container, and the like.
The shape of the mold is not particularly limited and can be appropriately selected depending on the intended purpose. It also includes a forming process using filling equipment such as a bento serving device for serving cooked rice in a relatively flat shape, a rice ball forming machine, and a sushi robot.

<<Freezing process after cooking>>
The step of freezing after cooking is a step of freezing the cooked rice after cooking.
The freezing is not particularly limited, and can be appropriately selected according to the purpose. A freezing treatment that is usually performed on food can be adopted, and quick freezing or slow freezing may be used.

<< Addition process of additives, etc. >>
The step of adding additives or the like is a step of adding additives or the like in any one of the steps in the method for producing cooked rice of the present invention.

The additives and the like are not particularly limited and can be appropriately selected depending on the intended purpose. Examples thereof include additives, seasonings, ingredients other than rice, and the like. These may be used individually by 1 type, and may use 2 or more types together.

The additives are not particularly limited and can be appropriately selected depending on the intended purpose. etc.), shelf life improvers, and quality improvers. These may be used individually by 1 type, and may use 2 or more types together.
The amount of the additive added is not particularly limited, and can be appropriately selected according to the purpose.

The seasoning is not particularly limited and can be appropriately selected according to the purpose. flour, saffron, etc. These may be used individually by 1 type, and may use 2 or more types together.
The amount of the seasoning to be added is not particularly limited, and can be appropriately selected according to the purpose.

The ingredients other than rice are not particularly limited and can be appropriately selected according to the purpose. Examples include vegetables, mushrooms, konjac, fried tofu, meat, seafood, seaweeds, and beans. These may be used individually by 1 type, and may use 2 or more types together.
The amount of ingredients other than rice to be added is not particularly limited, and can be appropriately selected according to the purpose.

(cooked rice)
The cooked rice of the present invention is produced through the above steps.
The cooked rice is not particularly limited as long as the mass of the cooked rice immediately after cooking is 250 parts by mass or more and 270 parts by mass or less with respect to 100 parts by mass of uncooked rice, and can be appropriately selected according to the purpose. From the viewpoint of taste, it is more preferably 250 parts by mass or more and 265 parts by mass or less, even more preferably 250 parts by mass or more and 260 parts by mass or less with respect to 100 parts by mass of uncooked rice. If it is less than 250 parts by mass per 100 parts by mass of uncooked rice, deterioration cannot be suppressed, and if it is more than 270 parts by mass per 100 parts by mass of uncooked rice, the taste and formability deteriorate.

The use of the cooked rice is not particularly limited and can be appropriately selected according to the intended purpose. Such cooked rice can be used, for example, for rice balls and boxed lunches displayed in convenience stores and supermarkets.

Examples of the present invention will be described below, but the present invention is not limited to these examples.

<Production of cooked rice>
(Production Example 1-1)
－Steam treatment process－
Weigh 300 g of Koshihikari (raw rice, rinse-free rice) produced in Niigata Prefecture in 2016 in a colander, put it in a steam chamber (steamer box K-1DX, manufactured by Arahata Seisakusho), and let it stand for 3 minutes at a temperature of 90 ° C or higher. . Mass was measured after steaming. Table 1 shows the mass increase (%) after steam treatment with respect to the mass of uncooked rice (Table 1: Increase (%) after steam treatment).

-Immersion process after steam treatment-
Immediately after measuring the mass, it was immersed in a bowl filled with 2 L of tap water adjusted to 25°C. It was allowed to stand in a constant temperature bath at 25°C for 1 hour. After 1 hour, the water was drained off, the rice was placed in a rice cooker (IH pot with a diameter of 18 cm), and the mass after immersion in water was measured. Table 1 shows the amount of mass increase (%) after soaking in water relative to the mass of uncooked rice (Table 1: Increase (%) after soaking in water).

-Rice cooking process-
1.65 times as much tap water as raw rice, oil with a final concentration of 0.5% (soybean oil, manufactured by Ajinomoto Co., Ltd.), and vinegar with a final concentration of 2.1% (grain vinegar, manufactured by Mizkan Co., Ltd.). added. After heating at an IH output of 700 W for 10 minutes and then at 200 W for 10 minutes, the rice was steamed at 90° C. for 30 minutes in a constant temperature bath to produce cooked rice. The mass of cooked rice immediately after cooking was measured, and the yield was calculated (mass of cooked rice after cooking/mass of uncooked rice×100). The yield (%) after cooking with respect to the mass of uncooked rice is shown in Table 1 (Table 1: Yield (%)). Moreover, the physical property measurement result was shown in FIG.

-Molding process-
The obtained cooked rice was loosened with a rice scoop, allowed to cool to about 50°C, then rapidly cooled to 20°C in a vacuum cooler, and molded in a commercially available triangular rice ball mold to produce a rice ball. Table 1 shows the moldability evaluation.

--Measurement of physical properties of cooked rice--
The physical properties of the cooked rice immediately after cooking were measured. A tensipressor (My Boy, manufactured by Taketomo Electric Co., Ltd.) was used for physical property measurement. Using a φ30 mm puncture probe, one grain of cooked rice was placed on the stage, and 20 rice grains were measured by “low/high compression measurement analysis 2”, and the stickiness of the surface layer was calculated from the average value.

--Moldability evaluation--
The stickiness, stickiness, and susceptibility to crumbling of rice balls molded in triangular rice balls were evaluated according to the following criteria.

(Evaluation criteria)
5: No problems with adhesion, stickiness, or ease of crumbling 4: Slightly crumbles due to lack of stickiness 3: Adheres to molded container, crumbles slightly 2: Adheres to molded container, sticky, crumbles 1: Molded container Very sticky, sticky, crumbling

(Production Example 1-2)
Cooked rice was produced in the same manner as in Example 1, except that the steaming time in the steaming step was changed from 3 minutes to 5 minutes. The amount of mass increase after steam treatment (%) relative to the mass of uncooked rice, the amount of mass increase (%) after immersion in water relative to the mass of uncooked rice, the yield (%) after cooking relative to the mass of uncooked rice, and the moldability evaluation. Table 1 shows. The physical property measurement results are shown in FIG.

(Production Example 1-3)
Cooked rice was produced in the same manner as in Example 1, except that the steaming time in the steaming step was changed from 3 minutes to 10 minutes. The amount of mass increase after steam treatment (%) relative to the mass of uncooked rice, the amount of mass increase (%) after immersion in water relative to the mass of uncooked rice, the yield (%) after cooking relative to the mass of uncooked rice, and the moldability evaluation. Table 1 shows. The physical property measurement results are shown in FIG.
After 10 minutes of steam treatment, after 1 hour of immersion in tap water, and after cooking, the samples were stained with eosin solution and observed with an optical microscope. Optical micrographs are shown in FIGS. 2A to 2C, respectively.

--Eosin staining--
After 10 minutes of steam treatment, after 1 hour of immersion in tap water, and after cooking rice, 10 μm-thick round slices were prepared using a microtome. The thin slice was stained by immersing it in an eosin solution for 5 minutes, and the thin slice was observed with an optical microscope.

---Preparation of eosin solution---
0.5 mL of acetic acid (manufactured by Junsei Chemical Co., Ltd.) was added to 500 mL of 1% eosin Y solution (manufactured by Mutoh Chemical Co., Ltd.) diluted 6-fold with 60% ethanol and mixed.

(Production Example 1-4)
Cooked rice was produced in the same manner as in Example 1, except that the steaming time in the steaming step was changed from 3 minutes to 20 minutes. The amount of mass increase after steam treatment (%) relative to the mass of uncooked rice, the amount of mass increase (%) after immersion in water relative to the mass of uncooked rice, the yield (%) after cooking relative to the mass of uncooked rice, and the moldability evaluation. Table 1 shows. The physical property measurement results are shown in FIG.

(Production Example 1-5)
Cooked rice was produced in the same manner as in Example 1, except that the steaming time in the steaming step was changed from 3 minutes to 30 minutes. The amount of mass increase after steam treatment (%) relative to the mass of uncooked rice, the amount of mass increase (%) after immersion in water relative to the mass of uncooked rice, the yield (%) after cooking relative to the mass of uncooked rice, and the moldability evaluation. Table 1 shows. The physical property measurement results are shown in FIG.

(Production Example 1-6)
Cooked rice was produced in the same manner as in Example 1, except that the steaming time in the steaming step was changed from 3 minutes to 60 minutes. The amount of mass increase after steam treatment (%) relative to the mass of uncooked rice, the amount of mass increase (%) after immersion in water relative to the mass of uncooked rice, the yield (%) after cooking relative to the mass of uncooked rice, and the moldability evaluation. Table 1 shows. The physical property measurement results are shown in FIG.

(Comparative Production Example 1-1)
Cooked rice was produced in the same manner as in Example 1, except that steam treatment was not performed in the steam treatment step. Table 1 shows the mass increase (%) after soaking in water relative to the mass of uncooked rice, the yield (%) after cooking relative to the mass of uncooked rice, and the evaluation of moldability. The physical property measurement results are shown in FIG.
The samples before immersion in tap water, 1 hour after immersion in tap water, and after rice cooking were stained with eosin solution and observed with an optical microscope. Optical micrographs are shown in FIGS. 2D to 2F, respectively.

(Comparative Production Example 1-2)
Cooked rice was produced in the same manner as in Example 1, except that the steam treatment was performed for 10 minutes while sprinkling water in the steam treatment step. The amount of mass increase after steam treatment (%) relative to the mass of uncooked rice, the amount of mass increase (%) after immersion in water relative to the mass of uncooked rice, the yield (%) after cooking relative to the mass of uncooked rice, and the moldability evaluation. Table 1 shows.

From the results in Table 1, it was found that in Production Examples 1-1 to 1-6, in which the steam treatment was performed for 3 to 60 minutes, the mass increase after the steam treatment was 110% or less. On the other hand, in Comparative Production Example 1-2 in which the steam treatment was performed while sprinkling water, it was found that the mass increase after the steam treatment was more than 110%.
In addition, in Production Examples 1-1 to 1-6 in which the steam treatment was performed for 3 to 60 minutes, it was found that cooked rice with a high yield of 250% and excellent formability could be produced. On the other hand, in Comparative Production Example 1-1 in which steam treatment was not performed and Comparative Production Example 1-2 in which steam treatment was performed while sprinkling water, the cooked rice was soft and sticky and had problems with moldability, and the quality was poor. It wasn't good.
In Production Example 1-3, in which steam treatment was performed for 10 minutes, a film-like layer was formed on the surface of the rice after 10 minutes of steam treatment (see FIG. 2A) and after 1 hour of immersion in tap water (see FIG. 2B). However, in Comparative Production Example 1-1, which was not steamed, the layer was not seen (see FIGS. 2D and 2E), and a sticky substance on the surface of the cooked rice was steamed. more common than rice.
From the results of FIG. 2, it was found that in Comparative Production Example 1-1, the surface layer of the cooked rice was highly sticky and moldability was poor. On the other hand, in Production Examples 1-1 to 1-6 in which the steam treatment was performed for 3 minutes to 60 minutes, the longer the steam treatment time, the less sticky the surface layer and the better the moldability.
From the above, it was found that by performing steam treatment, it is possible to produce cooked rice with a high yield, suppressed stickiness of the surface layer, and excellent formability. In addition, it is presumed that steam treatment can partially gelatinize the surface of the rice and suppress the outflow of starch (viscous substance) from the inside of the rice, thus suppressing the stickiness of the surface layer of the cooked rice. rice field.

<Texture evaluation of cooked rice after storage at room temperature>
(Production Examples 2-1 to 2-6)
-Molding process-
The cooked rice obtained in Production Examples 1-1 to 1-6 was loosened with a rice scoop, allowed to cool to about 50 ° C., then rapidly cooled to 20 ° C. with a vacuum cooler, and cut into commercially available triangular rice balls. It was molded to produce a rice ball. Moldability evaluation is shown in Table 2-1. Table 2-2 shows the texture evaluation of the rice balls immediately after molding. Table 2-3 shows the texture evaluation after standing at 20° C. for 24 hours.

--Texture evaluation (stored at room temperature)--
The texture of the cooked rice immediately after molding and after standing at room temperature was evaluated by a panel of 10 people according to the following evaluation criteria, and the average score was determined.

(Evaluation criteria)
Texture 5 points: No sense of incongruity at all, texture that can be eaten deliciously 4 points: Although it feels a little soft or hard, it feels quite delicious to eat 3 points: Although it feels soft and hard, it is a problem as a product No texture 2 points: A texture that is problematic as a product due to its considerable softness and hardness 1 point: A texture that is not suitable for cooked rice and is reluctant to eat

(Production Example 2-7)
Production Example 1-1, except that the steam treatment time was changed from 3 minutes to 10 minutes, and the amount of tap water during rice cooking was changed from 1.65 to 1.68 times the amount of uncooked rice. The cooked rice obtained in the same manner as in 2. is loosened with a rice scoop, left to cool to about 50 ° C., then rapidly cooled to 20 ° C. with a vacuum cooler, molded in a commercially available triangular rice ball mold, and made into a rice ball. manufactured. Moldability evaluation is shown in Table 2-1. Table 2-2 shows the texture evaluation of the rice balls immediately after molding. Table 2-3 shows the texture evaluation after standing at 20° C. for 24 hours.

(Production Example 2-8)
Production Example 1-1, except that the steam treatment time was changed from 3 minutes to 10 minutes, and the amount of tap water during rice cooking was changed from 1.65 to 1.75 times the amount of uncooked rice. The cooked rice obtained in the same manner as in 2. is loosened with a rice scoop, left to cool to about 50 ° C., then rapidly cooled to 20 ° C. with a vacuum cooler, molded in a commercially available triangular rice ball mold, and made into a rice ball. manufactured. Moldability evaluation is shown in Table 2-1. Table 2-2 shows the texture evaluation of the rice balls immediately after molding. Table 2-3 shows the texture evaluation after standing at 20° C. for 24 hours.

(Production Example 2-9)
Production Example 1-1, except that the steam treatment time was changed from 3 minutes to 10 minutes, and the amount of tap water during cooking was changed from 1.65 times the amount of uncooked rice to 1.82 times the amount of uncooked rice. The cooked rice obtained in the same manner as in 2. is loosened with a rice scoop, left to cool to about 50 ° C., then rapidly cooled to 20 ° C. with a vacuum cooler, molded in a commercially available triangular rice ball mold, and made into a rice ball. manufactured. Moldability evaluation is shown in Table 2-1. Table 2-2 shows the texture evaluation of the rice balls immediately after molding. Table 2-3 shows the texture evaluation after standing at 20° C. for 24 hours.

(Comparative Production Example 2-1)
Obtained in the same manner as in Production Example 1-1, except that steam treatment was not performed and the amount of tap water during cooking was changed from 1.65 to 1.46 times the amount of uncooked rice. The cooked rice was loosened with a rice scoop, allowed to cool to about 50°C, then rapidly cooled to 20°C in a vacuum cooler, and molded in a commercially available triangular rice ball mold to produce a rice ball. Moldability evaluation is shown in Table 2-1. Table 2-2 shows the texture evaluation of the rice balls immediately after molding. Table 2-3 shows the texture evaluation after standing at 20° C. for 24 hours.

(Comparative Production Example 2-2)
The cooked rice obtained in the same manner as in Production Example 1-1 was loosened with a rice scoop, except that the amount of tap water during cooking was changed from 1.65 to 1.46 times the amount of uncooked rice. , cooled to about 50°C, then rapidly cooled to 20°C in a vacuum cooler, and molded in a commercially available triangular rice ball mold to produce a rice ball. Moldability evaluation is shown in Table 2-1. Table 2-2 shows the texture evaluation of the rice balls immediately after molding. Table 2-3 shows the texture evaluation after standing at 20° C. for 24 hours.

(Comparative Production Example 2-3)
Production Example 1-1 except that the steam treatment time was changed from 3 minutes to 5 minutes, and the amount of tap water during rice cooking was changed from 1.65 times to 1.46 times the amount of uncooked rice. The cooked rice obtained in the same manner as in 2. is loosened with a rice scoop, left to cool to about 50 ° C., then rapidly cooled to 20 ° C. with a vacuum cooler, molded in a commercially available triangular rice ball mold, and made into a rice ball. manufactured. Moldability evaluation is shown in Table 2-1. Table 2-2 shows the texture evaluation of the rice balls immediately after molding. Table 2-3 shows the texture evaluation after standing at 20° C. for 24 hours.

(Comparative Production Example 2-4)
Production Example 1-1 except that the steam treatment time was changed from 3 minutes to 10 minutes, and the amount of tap water during rice cooking was changed from 1.65 times the amount of uncooked rice to 1.46 times the amount of uncooked rice. The cooked rice obtained in the same manner as in 2. is loosened with a rice scoop, left to cool to about 50 ° C., then rapidly cooled to 20 ° C. with a vacuum cooler, molded in a commercially available triangular rice ball mold, and made into a rice ball. manufactured. Moldability evaluation is shown in Table 2-1. Table 2-2 shows the texture evaluation of the rice balls immediately after molding. Table 2-3 shows the texture evaluation after standing at 20° C. for 24 hours.

(Comparative Production Example 2-5)
Production Example 1-1, except that the steam treatment time was changed from 3 minutes to 20 minutes, and the amount of tap water during cooking was changed from 1.65 times the amount of uncooked rice to 1.46 times the amount of uncooked rice. The cooked rice obtained in the same manner as in 2. was loosened with a rice scoop, allowed to cool to about 50°C, then rapidly cooled to 20°C in a vacuum cooler, and molded into a commercially available triangular rice ball. , made rice balls. Moldability evaluation is shown in Table 2-1. Table 2-2 shows the texture evaluation of the rice balls immediately after molding. Table 2-3 shows the texture evaluation after standing at 20° C. for 24 hours.

(Comparative Production Example 2-6)
Production Example 1-1, except that the steam treatment time was changed from 3 minutes to 30 minutes, and the amount of tap water during cooking was changed from 1.65 times the amount of uncooked rice to 1.46 times the amount of uncooked rice. The cooked rice obtained in the same manner as in 2. was loosened with a rice scoop, allowed to cool to about 50°C, then rapidly cooled to 20°C in a vacuum cooler, and molded into a commercially available triangular rice ball. , made rice balls. Moldability evaluation is shown in Table 2-1. Table 2-2 shows the texture evaluation of the rice balls immediately after molding. Table 2-3 shows the texture evaluation after standing at 20° C. for 24 hours.

(Comparative Production Example 2-7)
Production Example 1-1, except that the steam treatment time was changed from 3 minutes to 60 minutes, and the amount of tap water during rice cooking was changed from 1.65 to 1.46 times the amount of uncooked rice. The cooked rice obtained in the same manner as in 2. is loosened with a rice scoop, left to cool to about 50 ° C., then rapidly cooled to 20 ° C. with a vacuum cooler, molded in a commercially available triangular rice ball mold, and made into a rice ball. manufactured. Moldability evaluation is shown in Table 2-1. Table 2-2 shows the texture evaluation of the rice balls immediately after molding. Table 2-3 shows the texture evaluation after standing at 20° C. for 24 hours.

(Comparative Production Example 2-8)
The cooked rice obtained in Comparative Production Example 1-1 was loosened with a rice scoop, allowed to cool to about 50°C, then rapidly cooled to 20°C in a vacuum cooler, molded into a commercially available triangular rice ball, I made rice balls. Moldability evaluation is shown in Table 2-1. Table 2-2 shows the texture evaluation of the rice balls immediately after molding. Table 2-3 shows the texture evaluation after standing at 20° C. for 24 hours.

(Comparative Production Example 2-9)
Production Example 1-1, except that the steam treatment time was changed from 3 minutes to 10 minutes, and the amount of tap water during rice cooking was changed from 1.65 times to 1.9 times the amount of uncooked rice. The cooked rice obtained in the same manner as in 2. is loosened with a rice scoop, left to cool to about 50 ° C., then rapidly cooled to 20 ° C. with a vacuum cooler, molded in a commercially available triangular rice ball mold, and made into a rice ball. manufactured. Moldability evaluation is shown in Table 2-1. Table 2-2 shows the texture evaluation of the rice balls immediately after molding. Table 2-3 shows the texture evaluation after standing at 20° C. for 24 hours.

From the results in Tables 2-1 to 2-3, in Comparative Production Examples 2-1 to 2-7 in which water was added so that the yield was 230%, after standing at 20 ° C. for 24 hours compared to immediately after molding. I found myself feeling less.
In Comparative Production Example 2-8 (without steam treatment) in which water was added so that the yield was 250%, the texture was soft and sticky, and it was found that it could not be molded by machine, although it contained a large amount of moisture and suffered little deterioration.
In Comparative Production Example 2-9 (steam treatment for 10 minutes) in which water was added so that the yield was 275%, it was found that the texture was sticky and poor in texture despite the steam treatment.
On the other hand, in Production Examples 2-1 to 2-9 in which steam treatment was performed and water was added so that the yield was 250% to 270%, moldability was excellent, deterioration was small, and the texture immediately after molding was maintained. Do you get it.

From the above, it was found that the optimum treatment time is 3 minutes or more and 60 minutes or less, and the amount of water added at that time is an amount that makes the yield after rice cooking 250 to 270%.

<Texture evaluation of cooked rice after refrigerated storage>
(Production Example 3-1)
－Steam treatment process－
Weigh 300 g of Koshihikari (raw rice, rinse-free rice) produced in Niigata Prefecture in 2016 in a colander, put it in a steam chamber (steamer box K-1DX, manufactured by Arahata Seisakusho), and let it stand at a temperature of 90 ° C or higher for 10 minutes. .

-Immersion process after steam treatment-
Immediately after the steam treatment, it was immersed in a bowl containing 2 L of tap water adjusted to 25°C. It was allowed to stand in a constant temperature bath at 25°C for 1 hour. After 1 hour, the water was drained off, the rice was placed in a rice cooker (IH pot with a diameter of 18 cm), and the mass after immersion in water was measured.

-Rice cooking process-
1.65 times as much tap water as raw rice, oil with a final concentration of 0.5% (soybean oil, manufactured by Ajinomoto Co., Ltd.), and vinegar with a final concentration of 2.1% (grain vinegar, manufactured by Mizkan Co., Ltd.). added. Rice was cooked in the quick cooking mode of an IH rice cooker (SR-HC103: manufactured by Panasonic Corporation), and the rice was cooked for about 30 minutes and kept warm for about 20 minutes. (mass of cooked rice/mass of uncooked rice x 100).

-Molding process-
The cooked rice was loosened with a rice scoop, allowed to cool to about 50°C, then rapidly cooled to 20°C in a vacuum cooler, and molded into a commercially available tawara rice ball mold. Table 3 shows the evaluation of texture when stored at 10°C for 24 hours.

--Texture evaluation (refrigerated storage)--
Cooked rice that had been stored in a refrigerated state was heated in a microwave oven at 500 W, and the texture after the heat was removed was evaluated by a panel of 10 panelists according to the following evaluation criteria, and the average score was determined. The results are shown below.

(Evaluation criteria)
Texture 5 points: There is no sense of incongruity, and the texture is delicious. 4 points: The texture is slightly hard or the texture is not easily loosened, but the texture is quite delicious. 2 points: Texture that is problematic as a product due to its hardness or lack of loosening 1 point: Unsuitable as cooked rice and resistance to eating

(Comparative Production Example 3-1)
Obtained in the same manner as in Production Example 3-1 except that steam treatment was not performed and the amount of tap water during cooking was changed from 1.65 times the amount of uncooked rice to 1.46 times the amount of uncooked rice. The cooked rice was loosened with a rice scoop, allowed to cool to about 50°C, then rapidly cooled to 20°C with a vacuum cooler, and molded in a commercially available tawara rice ball mold to produce a rice ball. Table 3 shows the evaluation of texture when stored at 10°C for 24 hours.

(Comparative Production Example 3-2)
The cooked rice obtained in the same manner as in Production Example 3-1 was loosened with a rice scoop, allowed to cool to about 50°C, and then rapidly cooled to 20°C in a vacuum cooler. Then, it was molded in a commercially available tawara rice ball mold to produce a rice ball. Table 3 shows the evaluation of texture when stored at 10°C for 24 hours.

From the results in Table 3, it was found that the quality of the cooked rice that was steam-treated and cooked so as to have a high yield was improved after refrigerated storage.

<Texture evaluation of cooked rice after frozen storage>
(Production Example 4-1)
The rice balls produced in the same manner as in Production Example 3-1 were rapidly frozen (set temperature: -30°C) with a refrigerator (manufactured by Hoshizaki Denki Co., Ltd., "FR-603D-S"). Table 4 shows the evaluation of texture when the frozen rice balls were stored at -20°C for 14 days, and Table 5 shows the evaluation of stickiness.

--Texture evaluation (frozen storage)--
The cooked rice that had been left to stand in a frozen state was heated in a microwave oven at 500 W, and the texture after the heat was removed was evaluated by a panel of 10 panelists according to the following evaluation criteria, and the average score was determined. The results are shown below.

(Evaluation criteria)
Texture 5 points: No sense of incongruity at all, texture that can be eaten deliciously 4 points: Although it feels a little soft or hard, it feels quite delicious to eat 3 points: Although it feels soft and hard, it is a problem as a product No texture 2 points: A texture that is problematic as a product due to its considerable softness and hardness 1 point: A texture that is not suitable for cooked rice and is reluctant to eat

--Stickness degree evaluation--
The cooked rice that had been left to stand in a frozen state was heated in a microwave oven at 500 W, and the texture after the heat was removed was evaluated by a panel of 10 panelists according to the following evaluation criteria, and the average score was determined. The results are shown below.

(Evaluation criteria)
Degree of stickiness 5 points: Very good quality (non-stickiness) almost the same as before freezing 4 points: Slight adhesion between rice, good 3 points: Slight adhesion between rice, but No problem as a product 2 points: Too much adhesion between rice grains, poor 1 point: Remarkable adhesion between rice grains, very poor

(Production Example 4-2)
A rice ball produced in the same manner as in Production Example 4-1 except that the amount of tap water during cooking was changed from 1.65 to 1.68 times the amount of uncooked rice was heated at -20 ° C. Table 4 shows the texture evaluation after 14 days of static storage, and Table 5 shows the stickiness evaluation.

(Comparative Production Example 4-1)
Table 4 shows the texture evaluation when the rice balls produced in the same manner as in Comparative Production Example 3-1 were stored at −20° C. for 14 days, and Table 5 shows the stickiness evaluation.

(Comparative Production Example 4-2)
Table 4 shows the evaluation of texture when the rice balls produced in the same manner as in Comparative Production Example 3-2 were stored at −20° C. for 14 days, and Table 5 shows the evaluation of stickiness.

(Comparative Production Example 4-3)
A rice ball produced in the same manner as in Comparative Production Example 4-2 except that the amount of tap water during cooking was changed from 1.65 to 1.68 times the amount of uncooked rice was heated to -20°C. Table 4 shows the evaluation of texture when stored at rest for 14 days, and Table 5 shows the evaluation of stickiness.

(Comparative Production Example 4-4)
A rice ball produced in the same manner as in Production Example 4-1 except that the amount of tap water during cooking was changed from 1.65 times to 1.46 times the amount of uncooked rice was heated at -20 ° C. Table 4 shows the texture evaluation after 14 days of static storage, and Table 5 shows the stickiness evaluation.

From the results in Tables 4 and 5, the steamed rice cooked to a high yield was excellent in terms of texture and stickiness, which are problems that occur when frozen cooked rice is heated in a microwave oven. , It was also excellent in graininess. Therefore, it turned out that the quality after frozen storage improves.

Claims (5)

a steaming step of steaming uncooked rice that has not been immersed in water;
a soaking step of soaking the rice obtained in the steaming step in water;
A rice cooking step of cooking rice after the soaking step ;
A molding step of molding the cooked rice obtained in the rice cooking step ,
A method for producing cooked rice, wherein the mass of the cooked rice immediately after cooking is 250 parts by mass or more and 265 parts by mass or less per 100 parts by mass of uncooked rice. 2. The method for producing cooked rice according to claim 1, wherein the increase in mass of the uncooked rice after the steam treatment is 10 parts by mass or less per 100 parts by mass of the uncooked rice. The method for producing cooked rice according to claim 1 or 2, wherein the treatment time of the steam treatment is 3 minutes or more and 60 minutes or less. The method for producing cooked rice according to any one of claims 1 to 3, wherein the cooked rice is distributed at room temperature, refrigerated, or frozen without being heat sterilized. The method for producing cooked rice according to any one of claims 1 to 4, wherein in the soaking step, the soaking time is 3 minutes or longer, and the soaking temperature is 5°C or higher and 30°C or lower.

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