JP5565616B2 - Cooked rice suitable for preservation, cooked rice production method, and cooked rice processing improver used therefor - Google Patents

Description

The present invention relates to a technique for suppressing the change of cooked rice that tends to change in texture during storage (particularly during chilled storage). More specifically, cooked rice containing lecithin and sodium salt to suppress changes in texture during storage, a method for producing cooked rice that suppresses changes in texture during storage, and starch of cooked rice during storage The present invention relates to a rice processing improver capable of suppressing aging of rice.
Here, “at the time of storage” means not only the time of storage in a strict sense but also the time from manufacturing to the hands of consumers, including the time in the distribution stage and storefront. Concept.

In recent years, so-called “meal” where you can buy lunch boxes, prepared dishes, sushi, etc. that are sold at supermarkets and convenience stores, etc. Eating habits called are becoming popular.
In the prepared meals sold at convenience stores, etc., it has become a problem to dispose of a large amount of expired meals (for example, lunch boxes), starting with the efforts of major convenience store chains. There is a trend to start selling low-priced lunch boxes with long expiration dates.
That is, instead of storing the bento at around 20 ° C. as in the past, the bento is stored at a lower temperature, particularly in a chilled region at 10 ° C. or less (chilled storage), so that the expiration date is approximately 3 to 3. It is possible to extend it for 4 days, and as the expiration date is extended, it is expected that the rate of box lunch disposal will decrease.
Here, it is known that when cooked rice is stored for a certain period of time, the starch of the cooked rice will age, resulting in a hard and loose texture, but due to the low temperature lunch, the problem of this aging is It seems to be increasingly accelerated. This is because the degree of aging of rice starch is greater at lower temperatures.

  In addition, the aging of the starch of cooked rice is that the cooked rice is stored for a long period of time, so that water is released or localized from the starch that has been gelatinized in the cooking process, and a regular crystal arrangement close to the original raw starch (β starch) It is in a state of trying to return to.

  Aged rice is known to return to a texture close to the original plump rice by reheating it with a microwave oven, etc., but those using fresh ingredients such as sushi are reheated. It is difficult. Therefore, sushi rice placed in a low-temperature temperature zone for a long time is in a situation in which a decrease in texture associated with aging cannot be avoided.

Several methods for suppressing the aging of cooked rice have been proposed.
For example, a method of suppressing aging of cooked rice over time by cooking using a sugar having high water retention such as trehalose (see Patent Document 1), an enzyme (amylase and papain), an emulsifier (diglycerin fatty acid) A method for suppressing the aging of cooked rice using an ester is also proposed (see Patent Document 2 and Patent Document 3).
However, although both methods have a certain aging inhibitory effect, the present situation is that sufficient aging inhibition cannot be achieved.
Under such circumstances, there has been a strong demand for a method for suppressing the aging of cooked rice that has been stored for a certain period of time, particularly starch of cooked rice that has been stored at a low temperature.

Japanese Patent Laid-Open No. 7-147916 Japanese Patent Laid-Open No. 7-31396 JP-A-7-39325

The present invention has been made in view of the above problems, and a first object of the invention is to provide cooked rice that suppresses aging of starch of cooked rice that has been stored for a certain period of time under a temperature range of room temperature or lower, particularly at a low temperature. There is.
The second object of the present invention is to provide a method for producing cooked rice that suppresses the aging of the starch of cooked rice that has been stored for a certain period of time at a temperature range below room temperature, particularly at a low temperature.
The third object of the present invention is to provide a cooked rice processing improver that can suppress the aging of the starch of cooked rice when stored for a certain period of time in a temperature range of room temperature or lower, particularly at a low temperature.

  As described above, it is known that some emulsifiers are effective in inhibiting starch aging, and this effect is due to the hydrophobic bond between the starch chain and the hydrocarbon chain of the emulsifier, or the emulsifier incorporating the starch chain. This is probably due to micelle formation. If such an emulsifier-starch complex is formed, aggregation of starch chains accompanying aging is hindered, and it is considered that aging of the starch of cooked rice is suppressed.

  However, since emulsifiers have effects such as peculiar taste, nasty taste, aroma, and color change, there is a limit to the amount of use, especially for light-flavored foods such as cooked rice. There was also a limit.

Therefore, the present inventors have intensively studied a material that has a sufficient anti-aging effect and that does not have an adverse effect even when used for a light-flavored food such as cooked rice.
As a result, the present inventors can cook rice using a combination of lecithin, which is a kind of emulsifier, and a sodium salt, to obtain cooked rice with an extremely high antiaging effect, and also adversely affect the flavor of cooked rice. Based on this finding, the present inventors have completed the present invention.

In addition, when sodium salt is added during cooking, sodium promotes gelatinization on the surface of the rice, and this gelatinization layer inhibits the supply of water to the inside of the rice and inhibits the swelling of starch in the center of rice during cooking. ("Effects of calcium and sodium in rice cooking solution on properties of rice (Part 1) Effects on physical properties and taste of rice: Source: Journal of Japanese Society of Home Economics, Vol.57, No.10, 669-675 (2006) "). In addition, when sodium salt is added during cooking, the free water in the cooked rice is used to bind sodium ions during cooking, and as a result of the reduction of free water to gelatinize the starch, the starch does not sufficiently gelatinize. (Refer to "Iijima Memorial Food Science Foundation Annual Report (1998)").
In other words, the sodium salt was thought to work in the direction of promoting aging because it inhibits the alpha conversion of the center of cooked rice.

  Surprisingly, however, the sodium salt alone has no anti-aging effect (although it was thought to promote aging), but it has been found to exhibit a high anti-aging effect when combined with lecithin. Although this mechanism is not clear, it is considered that the sodium salt works synergistically when lecithin forms a complex with starch and suppresses aging of starch to a higher degree.

That is, the present invention is as follows.
(1): White rice or sushi rice containing 0.04 to 0.4 mass% of lecithin and 0.3 to 5.0 mass% of sodium salt based on the weight of raw rice.
(2): White rice or sushi rice according to (1), wherein the lecithin is in the range of HLB 9-14.
(3): The white rice or sushi rice according to any one of (1) to (2), wherein the white rice or sushi rice is stored for 6 hours or more in a temperature zone of 20 ° C. or less after production.
(4): Cooking rice after adding lecithin or lecithin-containing food and sodium salt or sodium salt-containing food to raw rice, and the sodium salt is sodium chloride, sodium citrate, sodium malate, and acetic acid A method for producing white rice or sushi rice comprising lecithin and a sodium salt, wherein the method comprises at least one selected from the group consisting of sodium .
(5): Lecithin or lecithin is added to raw rice so that the proportion of lecithin is 0.04 to 0.4 mass% and the proportion of sodium salt is 0.3 to 5.0 mass% with respect to the weight of raw rice. A method for producing white rice or sushi rice comprising lecithin and a sodium salt , wherein the rice is cooked after adding the containing food and the sodium salt or the sodium salt-containing food.
(6): Ri greens contain lecithin and sodium salt, and wherein the sodium salt is sodium chloride, sodium citrate, is sodium malate, and at least one member selected from the group consisting of sodium acetate A rice processing improver for white rice or sushi rice that can suppress aging of starch of white rice or sushi rice during distribution and storage at low temperatures.
(7): The cooked rice processing improver described in (6) above is 0.04 to 0.4% by mass of lecithin and 0.3 to 5.0% by mass of sodium salt based on the weight of raw rice. The method for producing white rice or sushi rice according to any one of the above (4) to (5) , wherein the rice is cooked after being added so as to become.

According to the present invention, with respect to cooked rice that is susceptible to changes in texture associated with aging of starch stored at room temperature, particularly at low temperatures for a certain period of time, it is possible to provide cooked rice that suppresses changes in texture associated with aging of starch. I can do it. In other words, for rice that is susceptible to changes in texture due to aging of starch stored at room temperature, especially at low temperatures for a certain period of time, it suppresses changes in texture without causing any changes in taste, taste, aroma, or color. Cooked rice can be provided.
Moreover, the manufacturing method of the cooked rice which suppressed the change of the food texture accompanying aging of such starch can be provided.
Furthermore, the cooked rice processing improvement agent which can suppress the change of the food texture accompanying aging of such starch can be provided.
As a result, cooked rice such as sushi rice can be stored for a long period of time, and as a result, the box lunch disposal rate can be reduced by extending the shelf life.

  The cooked rice in the present invention refers to cooked rice or processed products thereof, and examples of the cooked rice products include sushi rice, salted seasoned cooked rice for rice balls, and seasoned rice. The present invention is suitable for cooked rice with light flavor and sushi rice. Cooked rice as used herein refers to rice that has been added water and cooked, and sushi rice is prepared by adding vinegar, salt, sugar, etc. to the above cooked rice, such as seasoned vinegar. Add the seasoning.

The product form of cooked rice in the present invention is not particularly limited, but it is a convenience store, supermarket, and take-out side dish store that is distributed and sold in a temperature range of 25 ° C. or less, particularly 20 ° C. or less after production, after 6 hours or more. Lunch boxes, sushi, etc. sold in That is, as cooked rice, it is suitable for rice that has been stored for 6 hours or more in a temperature zone of 20 ° C. or less after production, and in particular, has been stored (chilled storage) for 6 hours or more in a chilled region of 10 ° C. or less.
In particular, it is suitable for pale white rice or sushi rice that does not use soy sauce or miso. This is because rice cooked with soy sauce or miso (cooked rice, etc.) is often heavily seasoned, and such cooked rice uses a certain amount of traditional anti-aging ingredients to some extent. It is hard to affect the taste. On the other hand, since it is difficult to use conventional aging-inhibiting materials for flavored white rice and sushi rice, it is highly necessary to use the materials of the present invention. In addition, the present invention is particularly suitable for cooked rice that cannot be reheated, such as sushi rice, because there is a great need to suppress aging.

  In addition, it is necessary to add the lecithin and sodium salt in this invention with water with respect to raw rice before a rice cooking process. This is because both act synergistically when the starch is gelatinized.

The lecithin in the present invention is phosphatidylcholine chemically and is structurally an amphiphilic substance having a hydrophilic group and a hydrophobic group. Although it is mainly produced from soybeans or egg yolks, those derived from soybeans that have little influence on the pale taste are preferred for use in cooked rice. Moreover, the thing whose HLB is 9-14 is desirable. The reason why the HLB is lower than 9 is because the aging inhibitory effect is relatively weak.
Lecithin may be contained in a form such as soybean lecithin and egg yolk lecithin, but can also be contained by adding lecithin-containing food such as egg yolk.

  The content of lecithin in cooked rice is required to be 0.04 to 0.4% by mass per raw rice (0.04 to 0.4 g per 100 g of raw rice), preferably 0.1 to 0 .4 mass%, particularly preferably 0.2 to 0.3 mass%. When the amount is more than 0.4% by mass, the egg flavor, nasty taste, fragrance, and color change specific to lecithin appear strongly, and the original flavor of the light white rice with the taste and fragrance is impaired. Moreover, when less than 0.04 mass%, the aging inhibitory effect of starch cannot fully be acquired.

In the present invention, as the sodium salt, for example, sodium chloride, sodium citrate, sodium malate, sodium acetate and the like can be used, and among these, the good taste of cooked rice is not impaired, the price is low, and the food The material sodium chloride is most preferably used.
Further, the sodium salt may be added as a single substance, or as a result, a sodium salt may be contained by adding a food or additive containing the sodium salt. Moreover, you may add a sodium salt in the said addition method 1 type, or in combination of 2 or more types.

The content of sodium salt of cooked rice is required to be 0.3 to 5.0% by mass per raw rice, and more preferably 1.0 to 3.0% by mass. As the upper limit, if it is more than 5.0% by mass, the salty taste is too strong, so it is not preferable as cooked rice. In particular, in the case of white rice having no salty taste, it is preferably 2.5% by mass or less, particularly 1.5% by mass, and more preferably 1.0% by mass or less. Moreover, if it is sushi rice, 5.0 mass% or less is required, Furthermore, 3.0 mass% or less is desirable.
The lower limit of the sodium salt content is 0.3% by mass, and if it is less than 0.3% by mass, the effect of suppressing starch aging synergistically with the sodium salt lecithin becomes difficult to obtain.

  Moreover, a lecithin and a sodium salt can also be added and used at the time of rice cooking as a composition (boiled rice processing improvement agent) which mixed both with water previously. In addition, the cooked rice processing improver said here is a seasoning adjusted beforehand so that a predetermined amount of lecithin and sodium salt may be added with respect to raw rice.

  In addition, food or food additives for imparting flavor or other functions, such as sugars such as reduced candy, various organic acids and organic acid salts, may be added to the cooked rice processing improver, if necessary. .

When using the said cooked rice processing improver in this invention, it is necessary to add with respect to raw rice before cooking rice. This is because lecithin and sodium salt in the cooked rice processing improver act during the gelatinization of starch.
After the rice cooker is added so that the ratio of lecithin is 0.04 to 0.4 mass% and the ratio of sodium salt is 0.3 to 5.0 mass% with respect to the weight of raw rice, rice is cooked. As a result, the desired cooked rice, that is, cooked rice that suppresses the aging of the starch of the cooked rice during distribution and storage at low temperatures can be obtained.

Next, an example of the method for producing cooked rice by adding the above-described cooked rice processing improver or the prescribed amounts of lecithin and salt will be described.
First, uncooked rice is washed and soaked with water by a conventional method to sufficiently absorb water. A predetermined amount of water and the above-mentioned cooked rice processing improver, or specified amounts of lecithin and sodium chloride are added to the absorbed rice and cooked. By the above method, cooked rice suitable for low temperature storage can be produced.

  Moreover, when manufacturing sushi rice, it is good to mix a certain amount of seasoning vinegar when the above rice is cooked, that is, after cooking. When salt is used as a sodium salt to be added before cooking rice, it is preferable to produce sushi rice by mixing the salt used in sushi vinegar minus the salt added earlier with the cooked rice.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

[Example 1]
(1) Cooked white rice containing lecithin and sodium salt 300 g of raw rice (Koshihikari from Fukushima Prefecture) was washed and immersed in water for about 1 hour. Next, after draining, after putting into a 5 rice kettle household rice cooker, each of the solutions of lecithin (0-0.9 g) and sodium chloride (0-6 g) shown in Tables 1-4 was added. Water was added so that the total weight in the kettle was 735 g. After stirring the inside of the kettle, it was cooked by heating by a conventional method. Then, heating was stopped and the cooking of rice was completed through a steaming process for 30 minutes.
The cooked rice prepared in this manner had a weight of about 660 g after cooling, and was formed on a disc by 60 g as a white rice sample.
In addition, as lecithin, soybean lecithin (Basis LP-20E: Nisshin Oillio Group Co., Ltd.) having an HLB of 14 was used.

(2) Evaluation of white rice aging by skilled sensory inspectors After the white rice sample prepared in the above process was allowed to stand at 5 ° C. for 24 hours, the product temperature was returned to room temperature. The degree of aging was evaluated according to the following criteria. The results are shown in Tables 1-4.
In the table, the concentration (mass%) of lecithin and sodium chloride contained in the white rice sample is the addition amount (g) of lecithin and sodium chloride to 100 g of raw rice.

[Evaluation criteria for aging]
(Double-circle): There is no aging of starch and food texture is also very favorable.
○: Starch is hardly aged and texture is good.
(Triangle | delta): Starch is aged a little and it is hard to texture, and feels slightly powdery.
X: Starch is aged, texture is hard and powdery.

From the above table, it was confirmed that white rice to which lecithin was added in an amount of 0.04% by mass or more and sodium salt in an amount of 0.3% by mass or more clearly suppressed aging as compared with the case of no addition of both materials. .
Moreover, the effect which suppresses aging is scarce in what added the lecithin simple substance, It has confirmed that the effect increased markedly by using sodium salt together. On the other hand, it was also confirmed that the sodium salt added alone had no effect of suppressing aging.
It is clear that the effect of suppressing such aging is particularly remarkable when lecithin is 0.2% by mass or more, and it is obvious that the sodium salt is 1.0% by mass or more. Became.
However, in the case of white rice, when 3.0% by mass of sodium salt is added, the effect on the taste is large, so that it is substantially 2.5% by mass or less, preferably 1.5% or less, most preferably 1. 0% by mass or less is considered good.
Although details are omitted, cooked rice to which 0.5% by mass of lecithin and appropriate amounts of sodium chloride (0.3% by mass, 1.0% by mass, 3.0% by mass, 5.0% by mass) are added is prepared. However, it has been found that although there is an effect of inhibiting aging, the eggy taste, nasty taste, fragrance, and color tone characteristic peculiar to lecithin are excessively increased, which is not preferable.

[Example 2]
Based on the results of Example 1, the aging inhibitory effect of sushi rice starch added with lecithin and sodium salt was verified over time.
(1) Preparation of sushi rice 300 g of fresh rice (Koshihikari from Fukushima Prefecture) was washed and immersed in water for about 1 hour. Next, after draining, the mixture was put into a 5 rice cooker household rice cooker, and a solution containing 0.3 g of lecithin and 4.5 g of sodium chloride was added to one test zone, and then lecithin was added to the other test zone. Water was added so that the total weight in the kettle would be 705 g without adding sodium chloride or sodium chloride. After stirring the inside of the kettle, it was cooked by heating by a conventional method. Then, heating was stopped and the cooking of rice was completed through a steaming process for 30 minutes.
A sushi rice sample was prepared by adding 66 ml of sushi vinegar (using the sushi vinegar shown in Table 5 for each test zone) to the above cooked rice and mixing them well onto a disc of 60 g.
The different sushi vinegar is used for each test zone in order to unify the amounts of vinegar, salt and sugar in the sushi rice of both test zones. That is, the salt of sushi vinegar used in the lecithin / sodium salt addition group is the amount obtained by subtracting the added amount because sodium chloride (salt) was added at the time of cooking in the test group.

(2) Aging evaluation of sushi rice by a skilled sensory inspector After leaving the sushi rice sample prepared in the above process for 0 to 36 hours at 5 ° C, after returning the product temperature to room temperature, our expert sensory inspection Each member evaluated the degree of aging according to the following criteria. The results are shown in Table 6.
In the table, the concentration (mass%) of lecithin and sodium chloride contained in the sushi rice sample is the addition amount (g) of lecithin and sodium chloride relative to 100 g of raw rice.

[Evaluation criteria for aging]
(Double-circle): There is no aging of starch and food texture is also very favorable.
○: Starch is hardly aged and texture is good.
(Triangle | delta): Starch is aged a little and it is hard to texture, and feels slightly powdery.
X: Starch is aged, texture is hard and powdery.

  From Table 6, it was confirmed that the sushi rice to which lecithin and sodium salt were added suppressed the aging over time as compared to the sushi rice to which neither material was added.

According to the present invention, with respect to cooked rice that is susceptible to changes in texture due to aging of starch stored at a room temperature or lower, particularly at a low temperature for a certain period of time, it is possible to provide cooked rice that suppresses changes in texture associated with aging of starch. It becomes possible.
In addition, with respect to cooked rice that is susceptible to changes in texture associated with aging of starch stored at a room temperature or lower, particularly at a low temperature for a certain period of time, a method for producing cooked rice that suppresses changes in texture associated with aging of starch is provided. It becomes possible.
Furthermore, it becomes possible to provide the cooked rice processing improver which can provide the cooked rice.

Claims (7)

  White rice or sushi rice characterized by containing 0.04 to 0.4 mass% lecithin and 0.3 to 5.0 mass% sodium salt based on the weight of raw rice.   The white rice or sushi rice of Claim 1 whose said lecithin is a thing of the range of HLB9-14.   The white rice or sushi rice according to any one of claims 1 to 2, wherein the white rice or sushi rice is stored for 6 hours or more in a temperature range of 20 ° C or lower after production. Cooking rice after adding lecithin or lecithin-containing food and sodium salt or sodium salt-containing food to raw rice, and the sodium salt consists of sodium chloride, sodium citrate, sodium malate, and sodium acetate A method for producing white rice or sushi rice comprising lecithin and a sodium salt, wherein the method comprises one or more selected from the above . With respect to the raw rice weight, the lecithin or lecithin-containing food is added to the raw rice so that the ratio of lecithin is 0.04 to 0.4 mass% and the ratio of the sodium salt is 0.3 to 5.0 mass%. A method for producing white rice or sushi rice comprising lecithin and a sodium salt , wherein rice is cooked after adding a sodium salt or a sodium salt-containing food. Ri Na contain lecithin and sodium salts, characterized in that said sodium salt is sodium chloride, sodium citrate, is sodium malate, and at least one member selected from the group consisting of sodium acetate, at low temperature A rice processing improver for white rice or sushi rice that can suppress the aging of starch of white rice or sushi rice during distribution and storage of rice. The cooked rice processing improver according to claim 6 is added so that the ratio of lecithin is 0.04 to 0.4 mass% and the ratio of sodium salt is 0.3 to 5.0 mass% with respect to the weight of raw rice. The method for producing white rice or sushi rice according to any one of claims 4 to 5 , wherein the rice is cooked after cooking.