JPH08116895A - Production of cooked rice and quality modifier for cooked rice - Google Patents

Abstract

PURPOSE: To obtain cooked rice having improved flavor from any nonglutinous rice by adding a protease acting at a temperature equal to or higher than the gelatinization temperature of rice starch to rice and cooking rice. CONSTITUTION: Raw rice is mixed with a thermostable protease acting at a temperature equal to or higher than the gelatinization temperature (55-80 deg.C) of rice starch in the weight ratio of the protease to the raw rice of 10<-2> to 10<-6> and cooked. Thermolysin (70 deg.C optimum temperature) is preferable as the thermostable protease. Cooked rice slightly collapsing, having gloss, swelling texture and viscosity free from dryness is obtained from nonglutinous rice including Indica rice.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing cooked rice and a quality improver for cooked rice. More specifically, the present invention is
The present invention relates to a method for producing cooked rice having improved taste and a quality improving agent for cooked rice, which is used for non-glutinous rice having poor taste. The “cooked rice” of the present invention means cooked rice including frozen cooked rice, pressure / heat sterilized cooked rice, and prepared cooked rice. In the present invention, "delicious" cooked rice means cooked rice with improved finish, texture, taste, etc., and gloss, that is, cooked rice with a Japanese taste and sticky rice.

[0002]

2. Description of the Related Art The deliciousness of cooked rice largely depends on the variety and quality of the rice, and if the variety is not optimal for the so-called white rice favored by Japanese people, no matter how the cooking method is devised, the taste will not improve. I have been told. However, there is a part of how cooked rice is cooked, and especially for rice of a variety that is not optimal for cooked rice, how to cook cooked rice becomes more important than ever to provide delicious cooked rice.
Inferior rice, such as indica rice, has a higher amylose content and protein content in starch, which is generally said to have a greater relationship with rice taste, compared to japonica rice, and its texture is that when cooked normally, japonica rice It is characterized by being harder and less sticky compared to. Although rice porridge and fried rice have the characteristic that they are not sticky, stickyness is an essential component of deliciousness when eating with cooked rice such as white rice, and rice cooked with indica rice has improved dryness and flavor. There are many points to do. There is a need for a method of cooking indica rice, which has low stickiness, to be eaten deliciously as cooked rice such as white rice.

[0003] Conventionally, the methods for improving the texture of rice, which has a poor taste, are as follows.
It is known to prolong the time of immersion in water, increase the amount of water added, treat with various enzymes such as protease, amylase, and cellulase, and use additives such as gelatin, agar, emulsifier, and thickener. . However, for example, when rice is cooked with an increased amount of water, it simply becomes soft and has no stickiness, and when a thickener is added, the cooked rice has an extraordinary stickiness, which greatly differs from the original texture of rice. In both cases, it is difficult to improve the texture significantly. Recently, oil-based rice cookers, intermediate starch hydrolysates, and hydromagnetic converters that are effective for cooking cooked rice are on the market, all of which are suitable for cooking delicious rice from polished rice suitable for cooked rice. Has an aim. Diversified eating habits,
Although the arrival of instant food and frozen food is remarkable, it is evidence that the popularity of delicious cooked rice has not declined.

The deliciousness of cooked rice is its appearance, odor, umami,
It is made up of various types of elements such as tenacity and hardness, making it difficult to make objective judgments. However, since rice varieties have also been improved and several varieties suitable for cooked rice are gaining popularity,
It can be said that the deliciousness of cooked rice is objectively evaluated. Demand will be concentrated on popular varieties, and the price will be high due to the planting area and crop failure. It is strongly desired to provide delicious cooked rice at low prices.

[0005]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a method for producing cooked rice and a quality improving agent for cooked rice, which are intended for sticky rice having poor taste.

[0006]

[Means for Solving the Problems] The present invention is
A method for producing cooked rice, which comprises adding a proteolytic enzyme that acts at a gelatinization temperature of rice starch or higher.

During rice cooking, rice starch is gelatinized by water and temperature. The gelatinization temperature of rice starch is 55 to 80 ° C.
These are divided into three groups: a type having a low gelatinization temperature (55-70 ° C), an intermediate type (70.5-74 ° C), and a type having a high gelatinization temperature (74.5-80 ° C).
In addition, the protein content in rice is closely related to the taste, and the higher the protein content, the harder the rice becomes and the more crunchy the texture.

The protein accumulated in rice grains exists in the form of protein granules (protein body I, protein body II). Protein body I consists of prolamin, and protein body II consists of glutelin and globulin. Of these, it is presumed that the heat-resistant protein body I has a problem in the taste.

It has been revealed that a 60 KD protein is present in rice starch granules. This 60KD protein has a characteristic that it cannot be removed by a conventional method for protein removal by washing with sodium hydroxide, sodium dodecyl sulfate or the like. In addition, it is widely distributed in rice with high amylose content. As a result of the test using Brabender, this 60KD
It was suggested that protein is related to taste.

When the present inventors add a proteolytic enzyme (hereinafter, may be abbreviated as "heat resistant protease") that acts at a temperature higher than the gelatinization temperature of rice starch during rice cooking, the heat resistant protease is cooked. It was hypothesized to act on protein body I and the 60KD protein. Then, in particular, in order to decompose or remove the 60KD protein, it was considered effective to swell rice starch and then carry out an enzyme attack.

The present invention is directed to glutinous rice polishing. Based on the results of the analysis by the present inventors of various types of Japanese rice and foreign rice, for example, Japonica rice Koshihikari has a starch content of 78.4% by weight, of which amylose is 15.
0% by weight and 85.0% by weight of amylopectin, whereas starch having poor taste, for example, indica rice, has a starch content of 79.1% by weight, of which amylose is 27.0%.
Weight% and amylopectin are 73.0% by weight, and one of the characteristics is that the ratio of amylose is high. The non-glutinous rice containing 20% by weight or more of amylose in the starch contained therein has insufficient stickiness and is not preferable to eat with white rice. The present invention is a rice cooking method for polishing non-glutinous rice, which is inferior in the taste represented by such indica rice.

As a method of adding the heat-resistant protease, it is effective to add it when the polished rice is immersed in water. Particularly, the effect of addition is easily obtained by a method of performing immersion in warm water, a method of performing at normal temperature and pressure for 3 to 4 hours, or a method of performing pressure reduction after adding the enzyme.

Further, when used in combination with an emulsifier, the enzyme permeability into rice is increased. Examples of preferable emulsifiers include organic acid monoglycerides, sucrose fatty acid esters, and polyglycerin fatty acid esters, which do not impair the flavor of cooked rice, but these may be used in combination. A high emulsifier HLB has a high effect on the permeability, and the addition amount is not particularly limited, but 0.001 to 1
It is preferable to add 2.0% by weight.

The thermostable protease used in the present invention is not particularly limited, but thermolysin (Protease S manufactured by Amano Pharmaceutical Co., Ltd., optimum action temperature 70 ° C.) is preferable. Papain W-40 (optimum temperature 45-65 ° C., manufactured by Amano Pharmaceutical Co., Ltd.) having a slightly lower optimum temperature than this enzyme and P having a lower optimum pH
The D enzyme (optimum temperature 75 ° C., optimum pH 2.5-3.0) had little effect.

The heat-resistant protease is added in an amount of 10 ⁻² to 10 ⁻⁶ by weight ratio with respect to raw rice. In this range of use, the above-mentioned thermostable protease was found to have an effect mainly on the softening of cooked rice, and also to prevent the aging of cooked rice.

[0016] The present invention is a method for producing cooked rice, which comprises adding a proteolytic enzyme that acts at a gelatinization temperature of rice starch or above and starch having 100% amylopectin or an intermediate decomposed product thereof during cooking rice. The taste of cooked rice is further improved by using the above enzyme in combination with 100% amylopectin starch or its intermediate decomposition product.

Examples of the amylopectin 100% starch include waxy cornstarch, pregelatinized waxy cornstarch, shiratama powder and pregelatinized shiratama powder. Waxy corn starch is 100% amylopectin starch containing no amylose component. Normally, starch is α1
→ 4-bond linear component (amylose) 20-25% and α1
It is composed of 75 to 80% of amylopectin branched by 6 bonds, but it is known that glutinous rice, waxy maize and the like are mostly composed of amylopectin. Waxy cornstarch is the starch of this waxy corn. Waxy cornstarch is resistant to aging, and is rich in viscoelasticity, swelling power, water retention, and gloss, so it is thought that it is a starch that has properties effective for improving the quality of cooked rice with poorly-polished rice .

The waxy cornstarch and / or shiratama powder can be added in an amount of 5% by weight or more, which is an amount capable of improving the texture by the gelatinization, that is, the decomposition in the gelatinized starch production process which is the modified starch. become. Pregelatinized starch retains the properties of waxy cornstarch, etc., which are suitable for improving the quality of cooked rice, such as viscoelasticity, swelling power, water retention, and luster. As a result, the heat convection and conduction will occur during rice cooking.
Preferably 1 to 10% by weight of pregelatinized waxy cornstarch and / or pregelatinized white syrup is added to rice having a poor taste during rice cooking. When the amount added is 5% or more, the texture is more effective, but when the amount added is more than 10%, the texture of rice cake becomes strong and the rice becomes too sticky.

The intermediate decomposition product of starch containing 100% amylopectin is one in which the molecular weight of starch is positively reduced. That is, in order to reduce the viscosity of the waxy corn starch solution, the molecular weight of starch is reduced, that is, it is used in the form of an intermediate decomposition product. According to the present invention, when the waxy cornstarch is decomposed to have a DE of 5 or less, the properties such as viscoelasticity, swelling power, water retention and luster that are suitable for a quality improving agent of cooked rice are maintained and used. The viscosity of the liquid can be reduced.

As a method for decomposing starch, enzymes, acid decomposition and the like can be used. For example, DE2-5 enzyme-decomposed waxy cornstarch is manufactured according to a conventional method, such as starch purification → enzyme liquefaction (acid or alkaline saccharification) → enzymatic saccharification (neutralization) → filtration → decolorization → filtration → ion exchange resin purification → decolorization →
It is manufactured through the usual process of filtration → concentration.

[0021] DE is an index showing the quality of a starch hydrolyzate produced by decomposing starch with an acid or an enzyme, and the direct reducing sugar contained in a solid substance is obtained as glucose. Is meant to
It can be expressed by the following formula. Properties such as sweetness, solubility, viscosity, aging property, hygroscopicity, and viscosity of a hydrolyzate of starch change depending on the degree of hydrolysis. The degree of hydrolysis of this starch is displayed as a DE value, which is a universal index.

When the degree of decomposition is larger than DE5, the properties inherent in waxy cornstarch such as viscoelasticity, swelling power, water retention and gloss are impaired, and as a result, these properties cannot be imparted to cooked rice. When rice is cooked with an inferior taste, when waxy cornstarch decomposed to a DE of 5 or less is added during rice cooking, it is added in an amount of about 1 to 20% by weight based on the rice milling raw material. The optimum addition amount is determined in consideration of the amount of heat-resistant protease to be used in combination, the type of rice milled, the convection of heat during rice cooking, etc. so that the rice can be cooked deliciously.

The present invention is a rice cooker characterized by containing a protease, amylopectin 100% starch or an intermediate decomposed product thereof. The rice cooker of the present invention may further contain an emulsifier as an essential component. These proteolytic enzymes, amylopectin 100
The components used in the above-described method of the present invention are used as the respective components of the starch, its intermediate decomposition product, and the emulsifier. This rice cooker can improve the taste of cooked rice simply by adding it at the time of cooking rice.

[0024]

EXAMPLES The present invention will be described with reference to examples. The invention is in no way limited by this example.

Example 1 After polishing 300 g of non-glutinous old rice, 450 g of water and a heat-resistant protease (Protease S, Amano Pharmaceutical Co., Ltd.)
1/1000 amount (made by weight)
u) added. Immerse it under reduced pressure (400 mmHg) for 1 hour, and then polish this rice with an automatic electric rice cooker (Matsushita Electric Co., Ltd.).
Made, electronic jar rice cooker SR-X05 rice cooking capacity 1.0l)
I cooked rice at. The obtained cooked rice was particularly good in terms of texture as compared with the one without addition.

Example 2 After polishing 300 g of non-glutinous old-polished rice, 473 g of pregelatinized waxy corn starch solution (3.2%) and heat-resistant protease (Protease S, manufactured by Amano Pharmaceutical Co., Ltd.) were applied to 1/100 of the raw rice. 1000 amount (weight ratio 3000u) was added. The rice was dipped under reduced pressure (400 mmHg) for 1 hour, and the rice was cooked with an automatic electric rice cooker (manufactured by Matsushita Electric Co., Ltd., electronic jar rice cooker SR-X05 rice cooking capacity 1.0 l). After cooking rice, sticky rice with soft inside was obtained.

Example 3 The cooked rice obtained in Example 2 was used as a control for 25
A comparative evaluation was performed by a panel of people. Table 1 shows the results. The numbers in the table represent the number of people.

[0028]

[Table 1]

Example 4 Table 2 shows the S / H value of each test section when rice was cooked with 1.65 times the amount of raw rice water added to Indica. The protease-added product (the amount added is the same as in Example 1) has a high S / even after 20 hours.
The H value was shown.

[0030]

[Table 2]

Example 5 300 g of non-glutinous rice milled rice and 1/175 amount of protease S and 475 g of 0.3% by weight glycerol distearate monostearate glycerin (Taiyo Kagaku, Sunsoft No.
641D, adjusted to pH 7.0) solution was added. After soaking for 2 hours at room temperature and atmospheric pressure, 15 g of pregelatinized waxy cornstarch was added and rice was cooked in an automatic electric rice cooker.
After cooking rice, soft and sticky rice was obtained.

Example 6 The cooked rice obtained in Examples 1, 2 and 5 was subjected to a sensory test.

[0033]

[Table 3] By adding the emulsifier, the same effect as that obtained by the vacuum immersion was obtained.

Example 7 The following powders were mixed to obtain a rice cooker. Protease S 10 g LAMEGIN DW 9000 100 g (Cheminche Fabric Grunau GmbH glycerine fatty acid ester of diacetyl tartrate) α-waxy corn starch 500 g

Example 8 493.3 g of water prepared by dissolving 18.3 g of the rice cooker obtained in Example 7 was added to 300 g of glutinous old rice milled rice and rice was cooked in an automatic rice cooker. After cooking rice, cooked rice of the same quality as in Example 5 was obtained.

[0036]

[Effects of the Invention] From any non-glutinous rice including indica rice, it is easy in terms of workability, has little collapse of cooked rice, is glossy, and has no dryness and gives a plump texture and stickiness. It is possible to produce cooked rice with improved taste.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ikuo Kimura 559-6 Kitano-cho, Hachioji-shi Central Research Institute of Japan Fisheries Stock Company

Claims (13)

[Claims] 1. A method for producing cooked rice, which comprises adding a proteolytic enzyme that acts at a gelatinization temperature of rice starch or higher during rice cooking. 2. The optimum action temperature of the protease is 6
The method for producing cooked rice according to claim 1, which is 0 ° C or higher. 3. The optimum action temperature of the protease is 7
The method for producing cooked rice according to claim 1, which is 0 ° C or higher. 4. The optimum action pH of the proteolytic enzyme is 6
The method for producing cooked rice according to any one of claims 1 to 3, wherein: 5. A starch comprising 100% amylopectin or an intermediate decomposition product thereof is further added.
One of the methods of making cooked rice. 6. The method for producing cooked rice according to claim 5, wherein the intermediate decomposition product has a DE of 5 or less. 7. Amylopectin 100% starch is α
The method for producing cooked rice according to claim 5 or 6, which is denatured waxy corn starch and / or pregelatinized white syrup. 8. The method for producing cooked rice according to claim 1, wherein indica rice is cooked. 9. Proteolytic enzyme, amylopectin 1
A rice cooker characterized by containing 00% of starch or an intermediate decomposition product thereof. 10. The rice cooker for nonglutinous rice according to claim 9, further comprising an emulsifier. 11. The rice cooker according to claim 9, wherein the intermediate decomposition product has a DE of 5 or less. 12. The rice cooker according to claim 10, wherein the starch containing 100% amylopectin is pregelatinized waxy cornstarch and / or pregelatinized white egg flour. 13. The rice cooker according to claim 9, which is a rice cooker for indica rice.