JP6923580B2 - Quality preserving agent for cooked rice and quality preserving method for cooked rice - Google Patents

Description

The present invention relates to a quality preserving agent for cooked rice and a method for maintaining the quality of cooked rice.

Due to the diversification of consumer lifestyles in recent years, for example, the demand for foods using cooked rice and refrigerated cooked rice sold at convenience stores and supermarkets is on the rise, and for that product, , A better texture is required.

So far, as a technique for suppressing the aging of foods, as a technique for suppressing the aging of rice cakes or noodles, for example, a method using maltotriosyltransferase (see, for example, Patent Document 1) has been proposed. ..
Further, a method for producing a cooked rice product with slow deterioration by contacting rice with an aqueous enzyme solution selected from the group consisting of maltose-producing alpha-amylase, branching enzyme, and a mixture thereof, and then cooking the rice. (For example, see Patent Document 2) or a technique for suppressing the aging of cooked rice without changing the taste quality of cooked rice by adding a branched oligosaccharide having a branched chain of maltose to cooked rice (for example, see Patent Document 2). (See Patent Document 3) has been proposed.

However, these proposed technologies cannot provide a texture that can sufficiently meet the demands of recent years, and further development of the technology is required.

On the other hand, in the food field, loss due to product disposal is becoming a serious situation, and there is concern that the cost required for product replacement due to labor shortage will increase. Therefore, extending the expiration date of the product has become an urgent issue. Therefore, from the viewpoint of extending the best-by date of cooked rice as compared with the conventional one, it is required to develop a technique capable of suppressing aging and providing cooked rice with an excellent texture.

Therefore, there is a strong demand for prompt provision of quality-preserving agents and quality-maintaining methods for cooked rice that provide an excellent texture even after refrigerated storage of cooked rice and can extend the expiration date more than before. The current situation is that there is.

International Publication No. 2012/105532 Special Table 2015-525564 Japanese Unexamined Patent Publication No. 2015-181412

An object of the present invention is to meet such a demand, break through the current situation, solve the above-mentioned problems in the past, and achieve the following objects. That is, the present invention provides a quality-preserving agent for cooked rice and a method for maintaining the quality of cooked rice, which can produce cooked rice with excellent softness while maintaining the graininess of cooked rice even after refrigerated storage. The purpose is.

As a result of diligent studies to achieve the above object, the present inventors have added and blended α-glucosyltransferase and glucoamylase to cooked rice during or after cooking, and acted on these enzymes to cook cooked rice. It was found that the cooked rice can be made into a cooked rice with excellent softness while maintaining the graininess of the rice even after the cooked rice is stored in a refrigerator.

The present invention is based on the above-mentioned findings of the present inventors, and the means for solving the above-mentioned problems are as follows. That is,
<1> A quality-preserving agent for cooked rice, which is characterized by containing α-glucosyltransferase and glucoamylase.
<2> The quality-preserving agent for cooked rice according to <1>, which is used in α-glucosyltransferase 10-900U and glucoamylase 30-500U with respect to 100 g of raw rice.
<3> Further containing at least one of malto-oligosaccharide and maltotriose, or used in combination with at least one of malto-oligosaccharide and maltotriose.
The quality-preserving agent for cooked rice according to <1> or <2>, wherein the amount of at least one of the maltooligosaccharide and maltotriose used is 0.01 to 1.0 g with respect to 100 g of raw rice. ..
<4> Further, at least one of α-amylase and protease is contained, and the amount of α-amylase used is 35 to 350 U and the protease is 20 to 250 U with respect to 100 g of raw rice. The quality preserving agent for cooked rice according to any one of 3>.
<5> The quality-preserving agent for cooked rice according to any one of <1> to <4>, wherein the compounding ratio of α-glucosyltransferase and glucoamylase is in the range of 5: 2 to 2: 5.
<6> A method for maintaining the quality of cooked rice, which comprises allowing α-glucosyltransferase and glucoamylase to act on cooked rice during or after cooking.
<7> The method according to <6>, which is used with α-glucosyltransferase 10-900U and glucoamylase 30-500U with respect to 100 g of raw rice.

According to the present invention, the above-mentioned problems in the prior art can be solved, and the cooked rice can be made into cooked rice with excellent softness while maintaining the graininess of the cooked rice even after being refrigerated. It is possible to provide a preservative and a method for maintaining the quality of cooked rice.

(Quality preserving agent for cooked rice)
The quality-preserving agent for cooked rice of the present invention contains at least α-glucosyltransferase and glucoamylase, and further contains other components as necessary. The quality-preserving agent for cooked rice of the present invention may be in a form containing all of α-glucosyltransferase, glucoamylase, and other components, or may be in a form in which at least one component is added separately. Further, the quality preserving agent for cooked rice may be in the form of solid (for example, powder, granular), liquid or a combination thereof.

<Rice>
The cooked rice (sometimes referred to as “cooked rice”) in the present invention is not particularly limited and may be appropriately selected. For example, cooked white rice, red rice, cooked rice, and white rice and barley are cooked together. Preferable examples thereof include cooked rice such as barley rice obtained by cooking rice, cooked rice obtained by cooking or steaming polished glutinous rice, cooked rice, cooked rice with ingredients such as brown rice, vinegared rice, chestnuts or beans.

<α-Glucosyl transferase>
The α-glucosyl transferase is an enzyme that transfers a part of 1,4-α-glucan to another part of a hydrocarbon such as glucose or 1,4-α-D-glucan.
The α-glucosyltransferase is not particularly limited as long as it can be used for food and drink (grade), and can be appropriately selected. However, the α-glucosyltransferase described in International Publication No. 2012/105532 (1). Malttriosyltransferase) is preferred. As the α-glucosyltransferase, a commercially available product can be used as appropriate.
The content of the α-glucosyltransferase in the quality preserving agent for cooked rice is not particularly limited and may be appropriately selected depending on the amount used, the activity and the like.

<Glucoamylase>
The official name of the glucoamylase is glucan 1,4-α-glucosidase, and glucose is obtained by hydrolyzing α-1,4-bonds and α-1,6-bonds at the non-reducing ends of sugar chains into exo-types. It is an amylase that produces one molecule.
The glucoamylase is not particularly limited as long as it can be used for food and drink (grade), and can be appropriately selected. For example, starch is sequentially decomposed from a non-reducing terminal in glucose (β type) units. Amyloglucosidase, gluca amylase, S-amylase, saccharified (type) amylase, and starch saccharifying enzyme, which are exo-type enzymes for performing the above, can be appropriately used. As the glucoamylase, a commercially available product such as Gluczyme AF6 manufactured by Amano Enzyme Co., Ltd. can be appropriately used.
The content of the glucoamylase in the quality preserving agent for cooked rice is not particularly limited and may be appropriately selected depending on the amount used, the activity and the like.

<Other ingredients>
The other ingredients are not particularly limited and may be appropriately selected as long as the effects of the present invention are not impaired. For example, α-amylase; protease; malto-oliose, maltotriose, maltodextrin and other food materials may be used. Can be mentioned. These may be used alone or in combination of two or more. Furthermore, when the quality-preserving agent for rice is solid, excipients such as starch, cellulose and sugar are used, and when it is liquid, the storage stability of enzymes such as α-glucosyltransferase and glucoamylase is obtained. Liquid components such as alcohol, polyhydric alcohol (glycerin, propylene glycol, etc.), sugar alcohol (erythritol, xylitol, sorbitol, mannitol, etc.), water candy, syrup, etc. may be contained.
Among these, in order to improve the softness of cooked rice, it is preferable to contain or use at least one of malto-oligosaccharide and maltotriose.
In addition, since the effect of maintaining the softness of cooked rice is improved, it is preferable to contain at least one of α-amylase and protease.
The content of the other components in the quality preserving agent for cooked rice is not particularly limited and may be appropriately selected.

-At least one of malto-oligosaccharide and maltotriose-
The malto-oligosaccharide and maltotriose are not particularly limited as long as they can be used for food and drink (grade), and commercially available products can be appropriately selected.
Either one of the malto-oligosaccharides and the maltotriose may be used, or both may be used.
The content of at least one of the maltooligosaccharide and maltotriose in the quality preserving agent for cooked rice is not particularly limited and may be appropriately selected depending on the amount and activity of the enzyme used.

-At least one of α-amylase and protease-
The α-amylase and protease are not particularly limited as long as they can be used for food and drink (grade), and commercially available products can be appropriately selected.

The type of the α-amylase is not particularly limited and may be appropriately selected. For example, the genus Bacillus such as Aspergillus oryzae, Bacillus subtilis, Bacillus amyloliquefaciens amylo. ), Bacillus such as Bacillus licheniformis, α-amylase derived from microorganisms such as Streptomyces, α-amylase derived from grains such as barley and wheat, and the like. These may be used alone or in combination of two or more.
The type of the protease is not particularly limited and may be appropriately selected. For example, the genus Aspergius such as Aspergillus oryzae and Aspergillus niger, Bacillus subtilis and the like. Proteases derived from microorganisms such as the genus Bacillus and Streptomyces; proteases derived from plants such as papaine, bromeline, actidinin, ficin and the like, pineapple, kiwi and figs. These may be used alone or in combination of two or more.

Either one of the α-amylase and the protease may be used, or both may be used. Further, an enzyme having both α-amylase activity and protease activity may be used, and examples thereof include Biozyme A of Amano Enzyme Co., Ltd.
The content of at least one of the α-amylase and the protease in the quality preserving agent for cooked rice is not particularly limited and may be appropriately selected depending on the amount used, the activity and the like.

<Aspect>
The quality-preserving agent for cooked rice may include the α-glucosyl transferase, the glucoamylase, and the other components, if necessary, in the same packaging material, or at least one of the components. One ingredient is put in separate packaging materials, and each ingredient is mixed before or during use, and the raw rice is soaked in raw rice before cooking rice, specifically in a liquid such as water, or in a state of being watered after soaking. It may be added to rice or cooked rice, or each component may be added to the raw rice or cooked rice, respectively. Further, as described above, the quality preserving agent for cooked rice may be in the form of solid (for example, powder, granular), liquid or a combination thereof, and can be appropriately selected.

<Usage>
The amount of the quality preserving agent for cooked rice is not particularly limited, and can be appropriately selected according to the amount of each component to be used, which will be described later.

−α-Glucosyl transferase −
The amount of the α-glucosyltransferase used is not particularly limited and may be appropriately selected, but usually 10 to 900 U (“U” represents an active unit (unit)) with respect to 100 g of raw rice. ), And preferably 60 to 300 U. If the amount of the α-glucosyltransferase used is less than 10 U, the cooked rice may not be given an appropriate graininess and softness, and if it exceeds 900 U, the cooked rice is excessively soft and the texture is deteriorated. Sometimes.

In the present invention, the definition of the active unit of α-glucosyltransferase is that the amount of enzyme that produces 1 μmol of glucose in 2.5 mL of the reaction solution per minute under the following conditions is 1 U.
-Conditions-
Add 0.5 mL of the enzyme solution to 2 mL of 10 mmol / L MES buffer (pH 6.5) containing 1% maltotetraose and leave at 40 ° C. for 60 minutes. After being left to stand, it is heated in a boiling water bath for 5 minutes and then cooled in running water to quantify the glucose produced.

-Glucosamylase-
The amount of the glucoamylase used is not particularly limited and may be appropriately selected, but is usually 30 to 500 U and preferably 60 to 160 U with respect to 100 g of raw rice. If the amount of glucoamylase used is less than 30 U, the cooked rice may not be given an appropriate graininess and softness, and if it exceeds 500 U, the cooked rice may be excessively soft and the texture may be deteriorated. be.

In the present invention, the definition of the active unit of glucoamylase is that the amount of enzyme that produces 10 mg of glucose in 30 minutes at pH 4.5 and 40 ° C. using starch as a substrate is 1 U.

--- α-Glycosyltransferase and glucoamylase compounding ratio ---
The compounding ratio of the α-glucosyltransferase and the glucoamylase is not particularly limited and may be appropriately selected, but the ratio of active units is preferably in the range of 5: 2 to 2: 5. More preferably, it is 5 to 1: 1. When the compounding ratio is within a preferable range, it is advantageous in that a good graininess and softness can be imparted to cooked rice.

-At least one of malto-oligosaccharides or maltotriose-
The amount of malto-oligosaccharide or maltotriose to be used is not particularly limited and may be appropriately selected, but is preferably 0.01 to 1.0 g with respect to 100 g of raw rice. , 0.02 to 0.7 g is more preferable. If the amount of at least one of the malto-oligosaccharide or maltotriose used is less than 0.01 g, the effect of blending is not exhibited, and even if it is blended in excess of 1.0 g, the effect is not so improved.

-At least one of α-amylase and protease-
The amount to be used when at least one of the α-amylase and the protease is used is not particularly limited and may be appropriately selected. In the case of the α-amylase, 35 to 350 U is preferable, and 70 to 140 U is more preferable with respect to 100 g of raw rice. In the case of the protease, 20 to 250 U is preferable and 45 to 90 U is more preferable with respect to 100 g of raw rice. When the amount of at least one of the α-amylase and the protease used is within a preferable range, it is advantageous in that good graininess and softness can be imparted to cooked rice.

In the present invention, the definition of the active unit of α-amylase is that starch is used as a substrate and reacted at pH 5.0 and 30 ° C. for 25 minutes and then colored with iodine, and the conversion rate of soluble starch at absorbance (620 nm) is determined. The amount of enzyme, which is 1.0 g per hour, is 1 U.

In the present invention, the definition of the active unit of the protease is as follows.
When 1 mL of enzyme solution was added to 5 mL of 0.6% milk casein (pH 7.5, M / 25 phosphate buffer) and reacted at 30 ° C. for 10 minutes, phorus color corresponding to 1 μg of tyrosin was developed per minute. The amount of enzyme released as a TCA-soluble component is 1 U.

(How to maintain the quality of cooked rice)
In the method for maintaining the quality of cooked rice of the present invention, α-glucosyltransferase and glucoamylase are allowed to act at least on cooked rice during or after cooking, preferably cooked rice, and if necessary, other components. Is used. In the present invention, "to act on cooked rice during cooking" means that the quality preserving agent is added to cooked rice before cooking, that is, raw rice immersed in a liquid such as water or watered after immersion. It means that at least α-glucosyltransferase and glucoamylase act at the time of cooking rice (the process of cooking rice). Further, in the present invention, rice cooking means a treatment by a cooking means usually applied to the production of cooked rice, such as a steaming treatment and a microwave oven treatment, in addition to heating by a normal rice cooker or the like.

<Usage>
The amounts of the α-glucosyl transferase and the glucoamylase used in the method for maintaining the quality of rice are not particularly limited as long as the effects of the present invention are not impaired, and can be appropriately selected. The amount can be the amount described in the <Usage amount> item of (Quality preserving agent for rice and rice).

The other components are not particularly limited as long as the effects of the present invention are not impaired, and can be appropriately selected. For example, the item <Other components> of the above-mentioned (quality preserving agent for cooked rice) of the present invention. The same can be said for the amount used.

In the method for maintaining the quality of cooked rice, the above-mentioned quality-preserving agent for cooked rice of the present invention can be preferably used.

According to the quality-preserving agent for cooked rice and the quality-maintaining method for cooked rice of the present invention, it is possible to obtain cooked rice with excellent softness while maintaining the graininess of the cooked rice even after the cooked rice is stored in a refrigerator.

Hereinafter, the present invention will be described with reference to Production Examples, Comparative Production Examples, and Test Examples, but the present invention is not limited thereto.

(Manufacturing Example 1)
α-Glucosyltransferase (Glycotransferase "Amano", manufactured by Amano Enzyme Co., Ltd., 3000 U / g) 5% by mass, glucoamylase (Gluczyme AF6, manufactured by Amano Enzyme Co., Ltd., 1600 U / g) 5% by mass, food material (maltodextrin) ) 90% by mass was mixed to prepare the preparation of Production Example 1.
When this preparation is used in an amount of 1% by mass based on 100 g of raw rice, it becomes α-glucosyltransferase 150U (150U / raw rice 100g) and glucoamylase 80U (80U / raw rice 100g).

(Comparative Manufacturing Example 1)
The preparation of Comparative Production Example 1 was prepared in the same manner as in Production Example 1 except that the amount of the food material was changed to 95% by mass without using glucoamylase.

(Comparative Manufacturing Example 2)
The preparation of Comparative Production Example 2 was prepared in the same manner as in Production Example 1 except that the amount of the food material was changed to 95% by mass without using α-glucosyltransferase.

(Test Example 1)
After polishing 100 parts by mass of raw rice (Uruchi rice) with tap water, 153 parts by mass of water is added, and 1% by mass (amount with respect to raw rice) of the preparation prepared in Production Example 1 or Comparative Production Examples 1 and 2 is further added. The rice was added, mixed and cooked in a rice cooker. The obtained cooked rice was refrigerated at 4 ° C. In addition, when no preparation is used (hereinafter, may be referred to as "additive-free"), the same test is performed when a preparation containing reduced starch syrup, brewed vinegar, salt, and acidulant is used as a comparative preparation. bottom.

<Evaluation>
-Hardness-
After storing at 4 ° C. for 1 day (Day 1), 3 days (Day 3), or 6 days (Day 6), range up 18 g of cooked rice (500 W, 30 seconds), and measure the hardness of the cooked rice using a creep meter as follows. It was measured under the measurement conditions of.
[Measurement condition]
・ Plunger: Circular (3 cm in diameter)
・ Measurement speed: 0.5 mm / sec
The load at a strain rate of 30% was defined as hardness (N).

-Texture-
After storage at 4 ° C. for 3 days, 18 g of cooked rice was ranged up (500 W, 30 seconds), and the texture of the cooked rice was evaluated according to the following evaluation criteria. The evaluation was performed by 10 people, and Table 1 shows the average score of the evaluation results.
[Evaluation criteria]
・ Texture 1 (hardness)
5 points: Moderately soft and plump.
4 points: Soft and slightly plump.
3 points: Slightly soft and weakly fluffy.
2 points: Slightly hard, sloppy, slightly sticky, or fluffy.
1 point: Hard, sloppy, sticky, or fluffy.
・ Texture 2 (graininess)
4 points: There is an appropriate graininess.
3 points: The graininess is a little weak.
2 points: The graininess is weak.
1 point: There is no graininess.

The evaluation results are shown in Table 1 below.

表１中、「Ｕ／１００ｇ」は生米１００ｇに対する酵素活性ユニットを示し、「ｇ／１００ｇ」は、生米１００ｇに対する添加量（ｇ）を示す（以下の表２〜５中の記載も同様）。

In Table 1, "U / 100 g" indicates an enzyme activity unit with respect to 100 g of raw rice, and "g / 100 g" indicates an addition amount (g) with respect to 100 g of raw rice (the same applies to the description in Tables 2 to 5 below). ).

As shown in Table 1, it was confirmed that the cooked rice using the formulation of Production Example 1 had an appropriate softness and graininess even after being refrigerated for several days after production. It was also confirmed that the physical properties (hardness / softness) and the results of the sensory evaluation correlate.

(Test Example 2)
Cooked rice was produced in the same manner as in Test Example 1 except that the preparations prepared so that the amount of each component used per 100 g of raw rice was the amount shown in Table 2 below were used. In addition, control cooked rice was produced in the same manner except that no preparation was used.
In Test Example 2, maltotriose was used as a food material.

<Evaluation>
-Texture-
The texture of cooked rice was evaluated in the same manner as in Test Example 1. The results obtained are shown in Table 2 below.

As shown in Table 2, it was confirmed that the effect of the present invention can be obtained even when the amount of α-glucosyltransferase is changed.

(Test Example 3)
Cooked rice was produced in the same manner as in Test Example 1 except that the preparations prepared so that the amount of each component used per 100 g of raw rice was the amount shown in Table 3 below were used. In addition, control cooked rice was produced in the same manner except that no preparation was used.
In Test Example 3, maltotriose was used as a food material.

<Evaluation>
-Texture-
The texture of cooked rice was evaluated in the same manner as in Test Example 1. The results obtained are shown in Table 3 below.

As shown in Table 3, it was confirmed that the effect of the present invention can be obtained even when the amount of glucoamylase is changed.

(Test Example 4)
Cooked rice was produced in the same manner as in Test Example 1 except that the preparations prepared so that the amount of each component used per 100 g of raw rice was the amount shown in Table 4 below were used. In addition, control cooked rice was produced in the same manner except that no preparation was used.
In Test Example 4, maltooligosaccharide or maltotriose was used as the food material.

<Evaluation>
-Texture-
The texture of cooked rice was evaluated in the same manner as in Test Example 1. The results obtained are shown in Table 4 below.

As shown in Table 4, it was confirmed that the softness of cooked rice was improved by containing at least one of maltooligosaccharide and maltotriose.

(Test Example 5)
Cooked rice was produced in the same manner as in Test Example 1 except that the preparations prepared so that the amount of each component used per 100 g of raw rice was the amount shown in Table 5 below were used. In addition, control cooked rice was produced in the same manner except that no preparation was used.
In Test Example 5, maltotriose was used as a food material.
In addition, the following enzymes were used as enzymes having α-amylase and protease activities.
・ Α-Amylase (Biozyme A, manufactured by Amano Enzyme Co., Ltd., 7,000 U / g)
・ Protease (Protease SD-NY10, manufactured by Amano Enzyme Co., Ltd., 7,000 U / g)

<Evaluation>
-Texture-
The texture of cooked rice was evaluated in the same manner as in Test Example 1. The results obtained are shown in Table 5 below.

As shown in Table 5, it was confirmed that the softness of cooked rice was improved by containing at least one of α-amylase and protease.

According to the quality preserving agent of the present invention, it is possible to obtain cooked rice with excellent softness while maintaining the graininess of cooked rice even after the cooked rice is stored in a refrigerator. Therefore, cooked white rice, red cooked rice, and cooked cooked rice can be obtained. Suitable for cooked rice such as barley rice obtained by cooking white rice and barley together, cooked rice obtained by cooking or steaming polished glutinous rice, cooked rice with ingredients such as brown rice, vinegared rice, chestnuts or beans. Can be used.

Claims (7)

Contains α-glucosyltransferase and glucoamylase ,
The raw rice 100 g, boiled rice for shelf agent characterized Rukoto used in α- glucosyltransferase 10~900U and glucoamylase 30～500U. In addition, it contains at least one of malto-oligosaccharides and maltotrioses, or is used in combination with at least one of malto-oligosaccharides and maltotrioses.
The quality-preserving agent for cooked rice according to claim 1, wherein the amount of at least one of the maltooligosaccharide and maltotriose used is 0.01 to 1.0 g with respect to 100 g of raw rice. The cooked rice according to claim 1 or 2, further containing at least one of α-amylase and protease, the amount of which is 35 to 350 U for α-amylase and 20 to 250 U for protease with respect to 100 g of raw rice. For quality preservatives. The quality-preserving agent for cooked rice according to any one of claims 1 to 3, wherein the compounding ratio of α-glucosyltransferase and glucoamylase is in the range of 5: 2 to 2: 5. Including the action of α-glucosyltransferase and glucoamylase on cooked rice during or after cooking.
A method for maintaining the quality of cooked rice, which comprises using α-glucosyltransferase 10 to 900 U and glucoamylase 30 to 500 U with respect to 100 g of raw rice. In addition, it involves allowing at least one of malto-oligosaccharide and maltotriose to act on cooked rice during or after cooking.
The method according to claim 5, wherein at least one of malto-oligosaccharide and maltotriose is used in an amount of 0.01 to 1.0 g with respect to 100 g of raw rice. In addition, it involves allowing at least one of α-amylase and protease to act on cooked rice during or after cooking.
The method according to claim 5 or 6, wherein α-amylase is used at 35 to 350 U and protease is used at 20 to 250 U with respect to 100 g of raw rice.