JP7733455B2 - Quality improver for cooked rice - Google Patents

Description

The present invention relates to a quality improver for cooked rice.

In recent years, there has been an increasing demand for cooked rice (chilled cooked rice and frozen cooked rice) that is distributed in a chilled or frozen state and sold in supermarkets, convenience stores, etc. However, cooked rice generally hardens over time when stored at low temperatures after cooking, and its texture deteriorates. As a result, many quality improvers for cooked rice have been proposed, using active ingredients such as thickening stabilizers such as gum arabic and pectin, organic acids such as lactic acid and citric acid and their salts, and enzymes such as proteases.

For example, disclosed are a cooked rice food product containing 0.12 to 3.00 parts by weight of pectin per 100 parts by weight of cooked rice solids and having a moisture content of 64 to 68% by weight (Patent Document 1), a quality improver for chilled or frozen cooked rice that contains (a) protease, (b) pectin and/or tamarind seed gum, and (c) a glycerin fatty acid ester (Patent Document 2), a quality improver for chilled or frozen cooked rice that contains (a) protease and (b) pectin or tamarind seed gum (Patent Document 3), and a taste improver for cooked rice that contains a non-volatile organic acid such as citric acid, a cold-water-soluble polymeric polysaccharide such as pectin, reduced starch syrup and/or dextrin (Patent Document 4).

However, the reality is that the above techniques are not necessarily sufficient to maintain the texture (e.g., graininess, moistness, softness) of cooked rice stored in a chilled state.

JP 2010-252773 A JP 2012-034611 A Japanese Patent Application Laid-Open No. 2008-245582 Japanese Patent Application Laid-Open No. 2004-159629

The object of the present invention is to provide a quality improver for cooked rice that can maintain the texture of cooked rice even when stored at low temperatures.

As a result of extensive research into the above-mentioned problems, the inventors discovered that the above-mentioned problems could be solved by a liquid formulation that combines two specific types of thickening polysaccharides with a starch hydrolysate having a specific DE value, and based on this finding, they developed the present invention.

That is, the present invention provides a liquid quality improver for cooked rice, characterized by containing the following (a) to (c):
(a) gum arabic,
(b) xanthan gum or pectin;
(c) starch hydrolysates having a DE value of 20 to 40.

The cooked rice obtained by adding the cooked rice quality improver of the present invention has an excellent texture even after storage at low temperatures.

The cooked rice quality improver of the present invention contains gum arabic as component (a), xanthan gum or pectin as component (b), and a starch hydrolysate with a DE value of 20 to 40 as component (c).

Gum arabic, component (a) of the cooked rice quality improver of the present invention, is obtained by drying or desalting the secretions of the Arabic gum tree (Acacia Senegal Willdenow) or other plants of the same genus, and is composed primarily of polysaccharides. Commercially available gum arabic can be used.

Xanthan gum, component (b) of the cooked rice quality improver of the present invention, is a polysaccharide produced extracellularly by Xanthomonas campestris and is composed of D-mannose, D-glucose, and D-glucuronic acid. Commercially available xanthan gum can be used.

Pectin, component (b) of the cooked rice quality improver of the present invention, is a polysaccharide such as methylated polygalacturonic acid obtained from citrus fruits, apples, etc., and includes, for example, high methoxyl pectin (HM) and low methoxyl pectin (LM), with high methoxyl pectin being preferred. Commercially available pectin can be used.

The starch hydrolysates, which are component (c) of the cooked rice quality improver of the present invention, are various intermediates obtained by hydrolyzing starch paste obtained by heating it with water with an acid or enzyme, and have a DE (Dextrose Equivalent) value of 20 to 40, preferably 27 to 38.

The DE value is generally an index showing the degree of starch decomposition, and indicates the proportion of dextrin and reducing sugars such as glucose and maltose produced when starch is hydrolyzed. The DE value is calculated by measuring reducing sugars as glucose using the Willstätter-Schudel method and calculating the ratio of the reducing sugars to 100% solids. The larger the DE value, the greater the reducing sugar content and the less dextrin, and conversely, the smaller the DE value, the less reducing sugar content and the more dextrin. That is, the DE value can be expressed by the following formula:
DE value = direct reducing sugars (expressed as glucose) / solids x 100

The quality improver for cooked rice of the present invention is preferably in the form of a preparation containing the above-mentioned components (a) to (c) and being liquid at room temperature (0 to 30° C.) The method for producing such a quality improver for cooked rice is not particularly limited, and any method known per se can be used, but it can be produced, for example, by the following steps (1) and (2).
Step (1): Components (a) to (c) are added to water and stirred at room temperature (15°C or higher but lower than 25°C) or while heating to 25 to 90°C, preferably about 50 to 80°C, to obtain a solution.
Step (2): If necessary, the solution obtained in step (1) is cooled to 40° C. or below to obtain a quality improver for cooked rice that is liquid at room temperature.

A mixer such as a propeller mixer, TK mixer (manufactured by Primix Corporation), or Clearmix (manufactured by M Techniques Co., Ltd.) can be used for the stirring in step (1) above. When using a TK mixer for stirring, the rotation speed is preferably 3,000 to 10,000 rpm, and the stirring time in step (1) is preferably approximately 1 to 60 minutes.

The cooked rice quality improver of the present invention is preferably adjusted so that, in 100% by mass, component (a) is 3.0 to 10.0% by mass, preferably 4.0 to 8.0% by mass, component (b) is 0.05 to 1.0% by mass, preferably 0.1 to 0.7% by mass, component (c) is 20 to 70% by mass, preferably 25 to 60% by mass, and the remainder is water.

In addition to the above components (a) to (c), the cooked rice quality improver of the present invention can also contain components used in preparing liquid formulations or improving the quality of cooked rice. Examples of such components include monosaccharides such as glucose and fructose; oligosaccharides such as sucrose, lactose, and maltose; maltooligosaccharides such as maltotriose, maltotetraose, maltopentaose, and maltohexaose; sugar alcohols such as sorbitol, mannitol, maltitol, reduced starch syrup, and glycerin; alcohols such as ethanol and propylene glycol; brewed vinegar; acetic acid; and acetate salts.

The cooked rice quality improver of the present invention can be added during cooking of cooked rice. Specific examples include a method of placing raw rice or washed rice and the cooked rice quality improver of the present invention in a rice cooker, adding water, and cooking the rice, or a method of placing raw rice or washed rice in a rice cooker, adding a prepared dispersion of the cooked rice quality improver of the present invention in water, and cooking the rice. There are no particular restrictions on the amount of water used for cooking the rice; for example, rice can be cooked with an amount of water added that is 1.5 to 1.7 times the mass of raw rice.

In the present invention, there are no particular restrictions on the amount of cooked rice improver added, but it is usually 0.5 to 10.0% by mass, and preferably 1.0 to 5.0% by mass, based on 100% by mass of raw rice.

There are no particular limitations on the type of rice cooker that can be used in the present invention, and examples include electric rice cookers, gas rice cookers, electromagnetic heating rice cookers, steam rice cookers, pressure cooker rice cookers, and other batch or continuous rice cookers and rice cooking equipment.

In addition to cooked rice obtained by cooking polished rice, examples of cooked rice according to the present invention include brown rice, red rice, steamed rice, seasoned rice, pilaf, fried rice, dry curry, sushi, rice balls, etc.

The above cooked rice can be produced as chilled cooked rice by storing the cooked rice in a chilled temperature range (e.g., 1 to 15°C) using standard methods, or as frozen cooked rice by freezing and storing the cooked rice at -5°C or below using standard methods.

The above-mentioned chilled cooked rice and frozen cooked rice can be eaten as is, for example, in the case of chilled sushi, but can usually be cooked and eaten using conventional methods. There are no particular restrictions on the cooking method, but examples include allowing the rice to return to room temperature, such as by natural thawing, or cooking it in a microwave oven.

The present invention will be explained in detail below using examples, but the present invention is not limited to these examples.

[Preparation of quality improver for cooked rice]
(1) Raw Materials 1) Gum Arabic (product name: Arabic Coal SS; manufactured by San-ei Pharmaceutical Trading Co., Ltd.)
2) Xanthan gum (trade name: GRINDSTED Xanthan Clear 80; manufactured by Danisco Japan Co., Ltd.)
3) HM pectin (trade name: UNIPECTINE AYD 5110SB; manufactured by Unitec Foods Co., Ltd.)
4) Guar gum (trade name: SUPERGEL CSA 200/50; Pakistan Gum and Chemical Company)
5) Glucomannan (trade name: Reolex One; manufactured by Shimizu Chemical Co., Ltd.)
6) Starch hydrolysate A (trade name: Maldeck PH400P; DE value: 33; manufactured by Showa Sangyo Co., Ltd.)
7) Starch hydrolysate B (trade name: SPD; DE value: 30; manufactured by Showa Sangyo Co., Ltd.)
8) Starch Hydrolysate C (trade name: Pine Index #3; DE value: 25; manufactured by Matsutani Chemical Co., Ltd.)
9) Starch Hydrolysate D (trade name: TK-16; DE value: 18; manufactured by Matsutani Chemical Co., Ltd.)
10) Starch Hydrolysate E (trade name: Pine Index #2; DE value: 11; manufactured by Matsutani Chemical Co., Ltd.)
11) Starch Hydrolysate F (trade name: Pine Index #100; DE value: 4; manufactured by Matsutani Chemical Co., Ltd.)
12) Sodium acetate (trade name: sodium acetate anhydride; manufactured by Daito Chemical Co., Ltd.)
13) Glacial acetic acid (trade name: 80% pure acetic acid; manufactured by Daicel Corporation)
14) Water

(2) Formulation of quality improvers for cooked rice The formulations of quality improvers for cooked rice 1 to 19 prepared using the above raw materials are shown in Tables 1 and 2. Of these, quality improvers for cooked rice 1 to 11 are examples according to the present invention, and quality improvers for cooked rice 12 to 19 are comparative examples.

(3) Manufacturing method of cooked rice quality improver Each raw material was added to water based on the blending ratios in Tables 1 and 2, and the mixture was stirred and dissolved at approximately 70°C and 5,000 rpm for 5 minutes using a TK mixer (model: TK HOMOMIXER MARK II, manufactured by Primix Corporation) to obtain a solution. The solution was cooled to 40°C or below at room temperature to obtain cooked rice quality improvers 1 to 19, which are liquid at room temperature. The amount of each improver prepared was 500 g.

[Test Example]
(1) Preparation of cooked rice 450 g of water was added to 300 g of raw rice (product name: Wash-free Koshihikari; manufactured by Senda Mizuho Co., Ltd.), and the mixture was left to stand at room temperature for 30 minutes. 3 g of each of cooked rice quality improvers 1 to 19 was then added and cooked in an electric rice cooker (model: JAI-R551; manufactured by Tiger Corporation). Next, the cooked rice was packed into 100 g portions in packaging containers (lid size: 110 mm × 130 mm × 18 mm; lid material: 0.15 mm thick polystyrene sheet; body size: 110 mm × 130 mm × 15 mm; body material: 0.35 mm thick polystyrene and polypropylene sheet) and allowed to cool.

(2) Evaluation test of cooked rice immediately after preparation A sensory test was conducted immediately after preparing cooked rice using the method in (1). In the sensory test, 10 panelists evaluated the rice according to the evaluation criteria shown in Table 3 below, and the average score was calculated and coded according to the following criteria. The results are shown in Table 5.
◎: average value 3.5 or more ○: average value 2.5 or more and less than 3.5 △: average value 1.5 or more and less than 2.5 ×: average value less than 1.5

(3) Evaluation test of chilled cooked rice The cooked rice prepared by the method in (1) was packed in a packaging container and stored in a refrigerator (model: 503D; manufactured by Hitachi Refrigeration Co., Ltd.) at about 5 ° C. for 48 hours, and then heated at 700 W for 40 seconds in a microwave oven (model: NE-SS30; manufactured by National Corporation) and subjected to a sensory evaluation. In the sensory test, evaluation was performed by 10 panelists according to the evaluation criteria shown in Table 4 below, and the average score was calculated and symbolized according to the following criteria. The results are shown in Table 5.
◎: average value 3.5 or more ○: average value 2.5 or more and less than 3.5 △: average value 1.5 or more and less than 2.5 ×: average value less than 1.5

The results in Table 5 show that cooked rice to which quality improvers for cooked rice 1 to 11 of the present invention were added maintained a good texture not only immediately after cooking but also when stored at low temperatures as chilled cooked rice. In contrast, cooked rice to which comparative quality improvers for cooked rice 12 to 19 were added was rated "Fair" or lower in all evaluation categories, and was inferior to cooked rice to which the quality improvers for cooked rice of the present invention were added.

Claims (1)

This method for maintaining the texture of chilled cooked rice involves adding a liquid quality improver for cooked rice to water used for cooking the rice, and the blending ratios of the following (a) to (c) are adjusted as follows in 100% by mass of the quality improver for cooked rice:
(a) Gum arabic 3.0 to 10.0% by mass
(b) 0.05 to 1.0% by mass of xanthan gum or pectin
(c) 20 to 70% by mass of starch hydrolysate having a DE value of 20 to 40