JP2021129520A - Method of preparing sushi rice - Google Patents

Abstract

To provide a method of preparing sushi rice, the quality of which is prevented from degrading during cold storage.SOLUTION: A method of preparing sushi rice of this invention includes steps of: (1) adding 155-185 pts.mass of water and 1.5-6.5 pts.mass of sugar to 100 pts.mass of polished rice and boiling the mix to obtain cooked rice; (2) adding 42-55 pts.mass of blended vinegar relative to 100 pts.mass of the polished rice, to the cooked rice obtained by (1) and, after the mix being immersed, mixing the mix; and (3) cooling the mix obtained by (2) to obtain the sushi rice.SELECTED DRAWING: None

Description

The present invention relates to a method for producing sushi rice. More specifically, the present invention relates to a method for producing sushi rice having resistance to refrigerated storage.

In recent years, sushi has been sold at supermarkets and convenience stores, and it is becoming more common to take it home and eat it. From the viewpoint of the time required for distribution and the expiration date at the store, the sushi distributed in this way can be distributed in a refrigerated state (0 to 10 ° C.), and it is preferable that the sushi can be stored refrigerated even after being lined up at the store. However, in general, when cooked rice is stored at a low temperature after cooking, it becomes hard with the passage of time and the texture deteriorates, so that it is difficult to keep cooked rice in a refrigerated state for a long period of time.
In addition, among sushi rice, especially in the case of sushi rice used for inari sushi, it is known that the hardening of sushi rice progresses in a short period of time due to the transfer of water from sushi rice to fried tofu during refrigerated storage. It was said that it was difficult to distribute and store.
Therefore, although there are requests from manufacturing, distribution, and sales sites, there are few cases where sushi rice that is actually distributed in a refrigerated state has been commercialized, and even if there is, the expiration date after lining up at the store is short, and Even within the expiration date, hardening due to aging was observed, and the quality was not sufficient.
As a method of suppressing deterioration of the texture of cooked rice during storage, there is a method of cooking rice by increasing the amount of water added during cooking (for example, Patent Documents 1 and 2). However, although it is possible to suppress dryness and hardening by such a method, there is a problem that the obtained cooked rice becomes too soft and easily crumbles, and subsequent processing such as processing into sushi rice or machine molding is difficult. ..
There is also a method of cooking rice by adding food additives such as sugars and sugar alcohols, enzymes, surfactants and thickening polysaccharides (for example, Patent Documents 3 and 4). However, the effect is still not sufficient, and there is a problem that the addition of these has an effect on the taste and appearance of cooked rice. In recent years, there is an industry demand for improvement methods that do not use additives due to health consciousness.
Both methods have a limited period of refrigeration resistance, and it is required to develop a method capable of more easily producing sushi rice having refrigeration resistance for a longer period of time (for example, at 0 to 10 ° C for more than 60 hours). ing.

Japanese Unexamined Patent Publication No. 2009-118760 Japanese Unexamined Patent Publication No. 9-191840 Japanese Unexamined Patent Publication No. 2012-175932 Japanese Unexamined Patent Publication No. 2001-178384

According to the present invention, sushi rice that does not easily deteriorate in quality even when refrigerated for a long time, for example, even if it is kept for about 24 to 75 hours, particularly for 50 to 75 hours, hardening due to aging is suppressed and a good texture is maintained. It is an object to provide a method for producing sushi rice that can be produced.

As a result of diligent studies to solve the above problems, the present inventor added (1) 155 to 185 parts by mass of water and 1.5 to 6.5 parts by mass of sugar to 100 parts by mass of polished rice. (2) (1) (1) (1) (1) (1) (1) (1) (1) The present invention has been completed by finding that a method for producing sushi rice, which comprises a step of cooling the mixture obtained in 2) to obtain sushi rice, can provide sushi rice in which quality is less likely to deteriorate due to refrigerated storage.

That is, the present invention includes the following aspects.
[1] (1) A step of adding 155 to 185 parts by mass of water and 1.5 to 6.5 parts by mass of sugar to 100 parts by mass of polished rice and cooking rice to obtain cooked rice.
(2) A step of adding 42 to 55 parts by mass of seasoned vinegar to 100 parts by mass of polished rice to the cooked rice obtained in (1), immersing the rice, and then mixing the rice, and the mixture obtained in (3) and (2). A method of producing sushi rice, including the process of cooling the rice to obtain sushi rice.
[2] The production method according to [1], wherein 2.7 to 5.5 parts by mass of sugar is added to 100 parts by mass of polished rice in the step (1).
[3] The production method according to the above [1] or [2], wherein 0.5 parts by mass or more of salt is not added to 100 parts by mass of polished rice in the step (1).
[4] The method according to any one of claims 1 to 3, wherein the cooling step is performed by vacuum cooling.
[5] The production method according to any one of [1] to [3] above, wherein the water content of the sushi rice after storage at 5 to 15 ° C. for 72 hours is 58 to 65% by mass.

According to the present invention, sushi rice that does not easily deteriorate in quality even when refrigerated for a long time, for example, even if it is kept for about 24 to 75 hours, particularly 50 to 75 hours, hardening due to aging is suppressed and a good texture is obtained. It is possible to produce sushi rice that can be maintained.

The method for producing sushi rice of the present invention is (1) a step of adding 155 to 185 parts by mass of water and 1.5 to 6.5 parts by mass of sugar to 100 parts by mass of polished rice to cook rice to obtain cooked rice. (2) A step of adding 42 to 55 parts by mass of seasoned vinegar to 100 parts by mass of polished rice to the cooked rice obtained in (1), immersing the rice, and then mixing the rice, and the mixture obtained in (3) and (2). Includes the step of cooling the rice to obtain sushi rice.

Generally, sushi rice is produced by washing polished rice, immersing it in water for a predetermined time, adding water to the cooked rice, adding vinegar to the cooked rice, mixing the rice, and cooling the cooked rice. The method for producing seasoned vinegar of the present invention basically includes the above-mentioned general steps, but its features will be described below.

In the production method of the present invention, in the step of obtaining cooked rice in the production of cooked rice, (1) 155 to 185 parts by mass of water and 1.5 to 6.5 parts by mass of sugar are added to 100 parts by mass of polished rice. Includes the process of cooking rice and obtaining cooked rice. By cooking rice with a predetermined amount of water added and an amount of sugar added, it is possible to suppress the hardness of the texture due to aging when refrigerated for a long time.
In the present invention, the amount of water added in the step (1) is preferably 155 to 175 parts by mass with respect to 100 parts by mass of polished rice. In the present invention, the amount of water added is an amount including the amount of water absorbed by the polished rice when the polished rice is washed and immersed in water.

In the present invention, the amount of sugar added in the step (1) is preferably 2.7 to 5.5 parts by mass with respect to 100 parts by mass of polished rice. Sugar is a sugar whose main component is sucrose (sucrose). The sugar added in the step (1) of the present invention can be used without particular limitation on the raw material and the production method. Examples of such sugar types include honey-containing sugar (brown sugar, white sugar, casonade (brown sugar), Japanese sanon tou, sorghum sugar, maple sugar, etc.) and honey-containing sugar (crude sugar, refined sugar). In the case of refined sugar, sugar (white sugar, medium sugar, granulated sugar), car sugar (white sugar, sanon tou), processed sugar (corn sugar, ice sugar, powdered sugar, granulated sugar) -Any liquid sugar may be used.
From the viewpoint of good flavor of the obtained sushi rice and ease of handling, it is preferable to use sanon tou.

In the present invention, polished rice can be used without being particularly limited to a variety or a production area as long as it is usually used for sushi rice.

In the present invention, preferably, 0.5 parts by mass or more of salt is not added to 100 parts by mass of polished rice in the step (1). More preferably, 0.3 parts by mass or more of salt is not added to 100 parts by mass of polished rice. More preferably, 0.2 parts by mass or more of salt is not added to 100 parts by mass of polished rice.

In the present invention, the rice cooking step in the step (1) can be carried out according to a conventional method except that the predetermined amount of water added and the amount of sugar added according to the present invention. Further, in the rice cooking step, various additives such as edible oils and fats, emulsifiers, alcohols, vinegar, modified starch, and brewed seasonings can be used as long as the effects of the present invention are not impaired.

In the production method of the present invention, 42 to 55 parts by mass of seasoned vinegar is added to 100 parts by mass of polished rice, soaked in the cooked rice obtained in (2) and (1) in the production of sushi rice, and then mixed. include. By adding a predetermined amount of seasoned vinegar, it is possible to suppress the hardness of the texture due to aging when refrigerated for a long time.
In the present invention, the amount of seasoned vinegar added in the step (2) is preferably 42 to 47 parts by mass. As the seasoned vinegar, one having a normal composition composed of vinegar, salt, sugars, seasonings and the like can be used. Add vinegar to the cooked rice and soak, preferably stand still for 30 seconds to several minutes and mix. When mixing, it is preferable to cut the cooked rice with a rice scoop so as not to crush the rice grains.

The production method of the present invention includes a step of cooling the mixture obtained in (3) and (2) to obtain sushi rice in the production of sushi rice. Preferably, the mixture obtained in (2) (rice cooked with seasoned vinegar) is cooled until the temperature becomes about 20 ° C. or lower. As a cooling method, there are a method of allowing to cool naturally, a method of forced cooling by refrigeration or vacuum cooling, and the like. From the viewpoint of shortening the time to reach the optimum temperature range (about 20 ° C to 50 ° C) for the growth of food poisoning bacteria as much as possible, and because the amount of water added and the amount of seasoned vinegar in steps (1) and (2) are larger than usual. From the viewpoint that the rice grains tend to crumble during mechanical production and the operability deteriorates, it is preferable to perform cooling by vacuum cooling, especially in the case of mass production.

The sushi rice produced by the production method of the present invention is made into sushi as it is or molded and combined with sushi seeds such as fish and shellfish to make sushi, and after being combined with seasoning to make sushi, it is placed in a container and stored in a refrigerator.
Refrigeration is carried out at 0 to 10 ° C., but the sushi rice obtained by the present invention has a good texture because hardening due to aging is suppressed even if it is kept in this state for about 24 to 75 hours, particularly 50 to 75 hours. Can be maintained. The sushi rice produced by the production method of the present invention is particularly suitable for making inari sushi.
The sushi rice produced by the production method of the present invention preferably has a water content of 58 to 65% by mass after being stored at 5 to 15 ° C. for 72 hours.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

<Manufacturing example 1: Manufacture of sushi rice 1>
(1) About 300 g of polished rice (domestic glutinous rice produced in the first year of Reiwa) was washed and then immersed in water for about 30 minutes.
(2) Drain the water of the soaked polished rice well, and 1.2 parts by mass of rice cooking oil (edible rapeseed oil, edible refined processed fats and oils) with respect to 100 parts by mass of polished rice before water addition, a predetermined amount of sugar and a predetermined amount of water. And an emulsifier) and 2 parts by mass of an improving agent (containing brewed vinegar, reduced water candy, starch decomposition product, brewed seasoning and 5% by mass of salt) were added, and rice was cooked in a household rice cooker by a conventional method.
(3) Add a predetermined amount of seasoned vinegar directly to the rice cooker containing the cooked rice, let stand for 30 seconds to several minutes, and then stir with a rice scoop so that the rice is not crushed. Spread the vinegar throughout the rice.
(4) The sushi rice was transferred to a tray lined with vinyl, covered with vinyl so that the surface did not dry, stored in a refrigerator set at 5 ° C. for 120 to 180 minutes, and cooled to 20 ° C. or lower to obtain sushi rice.
(5) 25 g of sushi balls were made from each of the cooled sushi rice and packed in inari rind (fried tofu made by OK Food Industry Co., Ltd.) to obtain inari sushi.

<Evaluation example 1: Sensory evaluation of the texture of sushi rice>
The processed or raw sushi rice was placed in a resin container and stored in a refrigerator at 5 ° C. At 24 hours, 48 hours, and 72 hours from the start of storage, 10 skilled panelists evaluated according to the evaluation table, and the average value and standard deviation were calculated. Based on the texture of cooked rice immediately after cooling (around 20 ° C) of cooked rice (control example 1) produced according to Production Example 1 with a water content of 130%, rice cooked without adding sugars, and seasoned vinegar of 45% by mass. 5 points were given, and the change in texture of sushi rice over time was evaluated.

Evaluation list

<Evaluation example 2: Measurement of water content of sushi rice>
The processed or raw sushi rice was placed in a resin container and stored in a refrigerator at 5 ° C. At 72 hours from the start of storage, the water content of the sushi rice (mass% of the mass of the sushi rice) was measured with a moisture meter (manufactured by Kett Science Institute).

<Test Example 1: Examination of water content>
As the amount of water added, the type and amount of sugar, and the amount of seasoned vinegar shown in Table 1, sushi rice was produced according to Production Example 1, and the texture and water content were evaluated according to Evaluation Example 1 and Evaluation Example 2. The amount of water added, the amount of sugar, and the amount of seasoned vinegar in the table are expressed in parts by mass with respect to 100 parts by mass of polished rice. The results are shown in Table 1.

Table 1

As a result, in Control Example 1, which had a normal amount of water added to sushi rice and no sugar was added, the texture deteriorated rapidly and aged to the extent that it could not be eaten 48 hours after storage. The amount of water added to 100 parts by mass of polished rice was increased to 170 parts by mass, and Comparative Example 1 without the addition of sugar had no problem in texture until 48 hours after storage, but could not be eaten after 72 hours. Aged. Control Example 2 in which the amount of water added to 100 parts by mass of polished rice was increased to 170 parts by mass and 2% by mass of trehalose was added as a saccharide maintained a good texture equivalent to that of sushi rice immediately after production until 48 hours after storage. It was possible to maintain a good texture even after 72 hours.
Comparative Example 2 in which the amount of water added was less than the predetermined amount of the present invention was so aged that it could not be eaten 72 hours after storage. All of Examples 1 to 3 within the range of the predetermined amount of water added in the present invention were able to maintain a good texture even 72 hours after storage. As the amount of water added increases, the texture tends to be slightly softer, and Example 1 in which the amount of water added is 160 parts by mass with respect to 100 parts by mass of polished rice is good, which is closest to the sushi rice immediately after production until 72 hours after storage. Maintained a nice texture.

<Test Example 2 Examination of saccharides>
As the amount of water added, the type and amount of sugar, and the amount of seasoned vinegar shown in Table 2, sushi rice was produced according to Production Example 1, and the texture and water content were evaluated according to Evaluation Example 1 and Evaluation Example 2. The amount of water added, the amount of sugar, and the amount of seasoned vinegar in the table are expressed in parts by mass with respect to 100 parts by mass of polished rice. The results are shown in Table 2.

その結果、本発明の所定量の糖類を含む実施例１、４〜６はいずれも保管後７２時間まで良好な食感を維持することができた。糖類の量が精白米１００質量部に対して６質量部である実施例５は若干甘味が強く感じられたが、すし飯の味として許容範囲であった。三温糖を使用した実施例１は、グラニュー糖を使用した実施例６と比較してより良好な食感を維持することができた。 Table 2

As a result, all of Examples 1, 4 to 6 containing a predetermined amount of saccharides of the present invention were able to maintain a good texture for up to 72 hours after storage. In Example 5 in which the amount of sugar was 6 parts by mass with respect to 100 parts by mass of polished rice, a slightly strong sweetness was felt, but the taste of sushi rice was within an acceptable range. Example 1 using sanon tou was able to maintain a better texture as compared with Example 6 using granulated sugar.

<Test Example 3 Examination of seasoned vinegar>
As the amount of water added, the type and amount of sugar, and the amount of seasoned vinegar shown in Table 2, sushi rice was produced according to Production Example 1, and the texture and water content were evaluated according to Evaluation Example 1 and Evaluation Example 2. The amount of water added, the amount of sugar, and the amount of seasoned vinegar in the table are expressed in parts by mass with respect to 100 parts by mass of polished rice. The results are shown in Table 2.

Table 3

Comparative Example 3, which was less than the amount of the predetermined seasoned vinegar added in the present invention, was aged to the extent that it could not be eaten 72 hours after storage. All of Examples 1 and 7, which were within the range of the amount of the combined vinegar added according to the present invention, were able to maintain a good texture for up to 72 hours after storage.

<Manufacturing example 2 Manufacturing of industrial scale sushi rice>
(1) About 1000 g of polished rice (domestic glutinous rice produced in the first year of Reiwa) was washed and then immersed in water for about 30 minutes.
(2) Drain the water of the soaked polished rice well, and 1.2 parts by mass of rice cooking oil (edible rapeseed oil, edible refined processed fats and oils) with respect to 100 parts by mass of polished rice before water addition, a predetermined amount of sugar and a predetermined amount of water. And 2 parts by mass of improving agent (including brewed vinegar, reduced water candy, starch decomposition product, brewed seasoning and 5% by mass of salt), and added a commercial rice cooker (MIK) " Rice cooked in automatic mode with "Rice Robo").
(3) Add a predetermined amount of seasoned vinegar directly to the rice cooker containing the cooked rice, and stir with a rice scoop so that the rice is not crushed so that the vinegar is distributed throughout the rice.
(4) Transfer the sushi rice to a tray lined with vinyl, cover it with vinyl so that the surface does not dry, and cool it to 20 ° C or less with a vacuum cooler (manufactured by Miura Co., Ltd.) at 15 to 30 hPa (time required 15 to 20 minutes). I got sushi rice.
(5) 25 g of sushi balls were made from each of the cooled sushi rice and packed in inari rind (fried tofu made by OK Food Industry Co., Ltd.) to obtain inari sushi.

<Test Example 4 Manufacture of industrial-scale sushi rice>
As the amount of water added, the type and amount of sugar, and the amount of seasoned vinegar shown in Table 3, sushi rice was produced according to Production Example 2, and the texture and water content were evaluated according to Evaluation Example 1 and Evaluation Example 2. The amount of water added, the amount of sugar, and the amount of seasoned vinegar in the table are expressed in parts by mass with respect to 100 parts by mass of polished rice. The results are shown in Table 4.

Table 4

Even in the case of mass production, a good texture could be maintained 72 hours after storage as in the case of producing a small amount.
Although no data is shown, vacuum cooling enables cooling in a shorter time than natural cooling or cooling in a refrigerator, which makes it possible to cool the food poisoning bacteria in the optimum temperature range (about 20 ° C). The time (~ 50 ° C.) could be shortened as much as possible.

Claims (5)

(1) A step of adding 155 to 185 parts by mass of water and 1.5 to 6.5 parts by mass of sugar to 100 parts by mass of polished rice and cooking rice to obtain cooked rice.
(2) A step of adding 42 to 55 parts by mass of seasoned vinegar to 100 parts by mass of polished rice to the cooked rice obtained in (1), immersing the rice, and then mixing the rice, and the mixture obtained in (3) and (2). A method for producing sushi rice, which comprises a step of cooling the rice to obtain sushi rice. The production method according to claim 1, wherein 2.7 to 5.5 parts by mass of sugar is added to 100 parts by mass of polished rice in the step (1). The production method according to claim 1 or 2, wherein in the step (1), 0.5 part by mass or more of salt is not added to 100 parts by mass of polished rice. The method according to any one of claims 1 to 3, wherein the cooling step is performed by vacuum cooling. The production method according to any one of claims 1 to 3, wherein the water content of the sushi rice after storage at 0 to 10 ° C. for 72 hours is 58 to 65% by mass.