Quality improver for cooked rice

Abstract

To provide a quality improver for rice and a food containing the quality improver for rice.SOLUTION: The quality improving agent for rice contains sodium lactate and sodium metaphosphate.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a quality improver for cooked rice. [Background technology]

[0002] In recent years, due to a shortage of domestically produced rice and rising rice prices caused by factors such as unseasonable weather and a decline in the agricultural workforce, the use of government stockpiled rice and imported rice has expanded. However, these rice varieties often have significantly inferior taste compared to newly harvested rice, particularly in terms of hardness and stickiness, and therefore do not meet consumer preferences. For commercial uses such as the restaurant industry, boxed lunches, and prepared foods, poor taste directly affects quality and customer satisfaction, so there are many challenges in adopting government stockpiled rice and imported rice. To improve the taste of such substitute rice, various techniques have been proposed to improve the texture and flavor of rice, such as by using various rice cooking methods, additives, and devising soaking processes.

[0003] Non-Patent Document 1 discloses a technique for improving rice stickiness by adding an enzyme such as pectinase to old rice. Patent Document 1 also discloses a technique for improving texture using a rice quality improver containing an enzyme such as phytase or pectinase, a sugar alcohol, and a pH adjuster. However, because these methods all require the use of enzymes, there is a problem in that there are limitations on the temperature and storage conditions required to prevent enzyme inactivation.

[0004] Non-Patent Document 2 discloses a technique for improving the texture of rice using calcium lactate and sodium chloride, but the sodium chloride contained in the rice increases the saltiness and thus affects the taste.

[0005] Patent Document 2 discloses a quality improver for cooked rice that uses one or more selected from phosphate and xanthan gum, dextrin, raffinose, β-amylase, and tapioca starch to inhibit staling of cooked cooked rice and maintain its texture. However, this method has problems such as the fact that only frozen cooked rice is evaluated, and the evaluation results for conditions other than frozen storage are unknown, and the evaluation items are based on sensory evaluation of appearance, stickiness, and degree of staling, so improvements in hardness, etc. are not clear. [Prior art documents]

[0006] [Patent Document 1] Patent Publication No. 2011-30511 [Patent Document 2] Patent Publication No. 2024-159328 [Non-Patent Document 1] Improving the Taste Characteristics of Old Rice Michiko Watanabe Starch Science Vol. 40 No. 2 pp. 163-168 (1993) [Non-patent document 2] Effect of calcium and sodium in rice cooking solution on the properties of cooked rice (Part 1) Effect on the physical properties and taste of cooked rice Journal of the Japan Society of Home Economics Vol.57 No.10 p.669~675 (2006) Summary of the Invention [Problem to be solved by the invention]

[0007] Such conventional techniques have had problems with cooked rice, such as the use of enzymes resulting in restrictions on special temperature and storage conditions, the use of sodium chloride affecting the taste, and the fact that the retention of hardness and stickiness over time is not fully understood. [Means for solving the problem]

[0008] The present invention aims to provide a versatile quality improver for cooked rice, which can maintain the hardness and stickiness of rice immediately after cooking for a certain period of time by using sodium lactate and sodium metaphosphate in combination, and does not require special temperature or storage conditions. [Effects of the Invention]

[0009] The quality improver for cooked rice of the present invention is able to maintain the hardness and adhesiveness of rice immediately after cooking even after 48 hours at 15° C. This was evaluated assuming a temperature environment (generally 4 to 15° C) such as in showcases in convenience stores and supermarkets where products made with cooked rice, such as rice balls and bento lunches, are displayed, or in commercial or household refrigerators, and its ability to maintain quality for 48 hours at 15° C demonstrates that it can exhibit sufficient quality preservation effects even under actual distribution and sales conditions. DETAILED DESCRIPTION OF THE INVENTION

[0010] The quality improver for cooked rice of the present invention contains sodium lactate and sodium n H2P n O 3n+1 The sodium metaphosphate of the present invention is characterized by containing sodium metaphosphate represented by the formula:

[0011] The amount of sodium lactate added to the quality improver for cooked rice of the present invention is preferably 0.01% by mass to 10% by mass, more preferably 0.05% by mass to 5% by mass, and most preferably 0.1% by mass, relative to the mass of raw rice.

[0012] The sodium content of the quality improver for cooked rice of the present invention n , H2P n O 3n+1 The amount of sodium metaphosphate added, expressed as above, is preferably 0.01% by mass to 10% by mass, more preferably 0.05% by mass to 5% by mass, and most preferably 0.2% by mass, relative to the mass of raw rice.

[0013] Na used in the present invention n H2P n O 3n+1 In the sodium metaphosphate represented by the formula (I), n is preferably 14 or more, and most preferably 20 or more. Sodium metaphosphate having an average degree of polymerization of 14≦n<20 is considered to be low-polymerized sodium metaphosphate, and sodium metaphosphate having an average degree of polymerization of n≧20 is considered to be high-polymerized sodium metaphosphate.

[0014] The quality improver for cooked rice of the present invention may be in the form of a powder or liquid, but sodium lactate commonly available as a food additive is often in the form of an aqueous solution (e.g., 50% concentration), so when 50% sodium lactate is used as the quality improver for cooked rice of the present invention, a liquid quality improver for cooked rice is usually obtained.

[0015] The raw rice used to make cooked rice is not particularly limited as long as it belongs to the Oryza genus, and there are no limitations on the brand, place of origin, or milling date. Examples include the American rice (Calrose rice, milling date unknown) used in the examples and government stockpiled rice (very old rice, a blend of Miyagi Prefecture-grown Hitomebore and Miyagi Prefecture-grown Sasanishiki rice, milled in July 2025).

[0016] The quality improver for cooked rice of the present invention can be used on all types of cooked rice, including white rice, brown rice, and glutinous rice. Specifically, it can be used in a variety of cooked rice dishes, whether Japanese, Western, or Chinese, including seasoned rice, fried rice, rice balls, risotto, paella, soup, red rice, pilaf, sticky rice, and rice porridge. It is also effective whether the product is stored frozen, chilled, or at room temperature, and can be used in a wide range of situations, including the restaurant industry, commercial uses such as boxed lunches and prepared dishes, and home cooking.

[0017] The present invention will be described in detail below with reference to experimental examples, but the present invention is not limited to these experimental examples.

[0018] [Comparative Examples 1 to 4, Examples 1 to 2] Rice washing was defined as a process in which 450 g of each type of polished rice was washed with three times the mass of purified water (27°C) at a speed of twice per second for 30 seconds, and the water was discarded. This washing process was repeated three times. The rice was then drained and immediately placed in an electric rice cooker (Tiger Corporation, Model No. JBH-G102W). 600 g of an aqueous solution containing sodium lactate (Taihei Chemical Industry Co., Ltd.) and sodium metaphosphate (Taihei Chemical Industry Co., Ltd.) in the proportions shown in Table 1 was added and cooked. After cooking, the polished rice samples were promptly transferred to a rice storage container (Asahi Kasei Home Products Corporation) and left to stand in an incubator set at 15°C for up to 48 hours. The obtained white rice samples were measured using a texture analyzer (Shimadzu Corporation, model number: EZ-LX) immediately after cooking, after 24 hours of storage at 15°C, and after 48 hours of storage at 15°C. The measurement conditions were as follows: 10 g of white rice sample was filled into a 40 mm diameter sample container to a height of 15 mm, and the sample was compressed twice using a 20 mm diameter cylindrical plunger at a compression speed of 10 mm / s with a clearance of 5 mm. Average values ​​for hardness and adhesiveness were calculated from the texture record curves (n=7) obtained during this process.

[0019] [Table 1]

[0020] The results of the texture analyzer (Comparative Examples 1 to 4, Examples 1 and 2) are shown in Table 2 and FIGS.

[0021] [Table 2]

[0022] In the case of no additive (Comparative Example 1) or with the addition of 0.1% by mass of sodium lactate (Comparative Example 2), both Calrose rice and old rice showed significant increases in hardness and adhesiveness after 24 hours of storage at 15°C. In the case of the addition of 0.2% by mass of low-polymerized sodium metaphosphate (Comparative Example 3), Calrose rice maintained the same hardness and adhesiveness as immediately after cooking after 24 hours of storage at 15°C, but after 48 hours of storage at 15°C, the hardness and adhesiveness significantly increased compared to immediately after cooking. Old rice showed significant increases in hardness and adhesiveness after 24 hours of storage at 15°C. In the case of the addition of 0.2% by mass of high-polymerized sodium metaphosphate (Comparative Example 4), Calrose rice maintained the same hardness and adhesiveness as immediately after cooking after 24 hours of storage at 15°C, but after 48 hours of storage at 15°C, the hardness significantly increased and the adhesiveness was similar to that after immediately after cooking. Old rice showed significant increases in hardness and adhesiveness after 24 hours of storage at 15°C. In contrast, when 0.1% by mass of sodium lactate and 0.2% by mass of low-polymerized sodium metaphosphate were added (Example 1), and when 0.1% by mass of sodium lactate and 0.2% by mass of high-polymerized sodium metaphosphate were added (Example 2), the rice retained the same hardness and adhesiveness as immediately after cooking even after 48 hours of storage at 15°C. Furthermore, when Example 1 and Example 2 were compared, Example 2 retained the hardness and adhesiveness of the rice without additives immediately after cooking even after 48 hours of storage at 15°C for both Calrose rice and old rice. Experimental Example 2

[0023] Immediately after cooking, after 24 hours at 15°C, and after 48 hours at 15°C, white rice samples were subjected to sensory evaluation and compared for texture. The sensory evaluation was conducted to evaluate the texture of the white rice, focusing on hardness and adhesiveness. The definitions of each evaluation item are shown in Table 3. As shown in Table 4, five panelists evaluated the rice using a 7-point scale ranging from 0 (control product; immediately after cooking) to ±3, and the average was calculated. The ten evaluations and evaluation terms for each item are shown in Table 5.

[0024] [Table 3]

[0025] [Table 4]

[0026] [Table 5]

[0027] The results of the sensory evaluation are shown in Table 6.

[0028] [Table 6]

[0029] The results of the sensory evaluation showed that Examples 1 and 2, compared to Comparative Examples 1 to 4, showed less reduction in hardness and adhesiveness, and maintained a texture similar to that immediately after cooking. In particular, Example 2 maintained a texture almost equivalent to that immediately after cooking for 48 hours, both for Calrose rice and old rice. These trends in sensory evaluation showed a high correlation with the measurement results obtained with the texture analyzer. Furthermore, in the evaluation of taste, Examples 1 and 2 showed higher scores than the comparative examples. These results confirmed that the quality improver for cooked rice of the present invention is effective in both physical property evaluation and sensory evaluation. [Industrial Applicability]

[0030] The present invention enables rice, such as aged rice or American rice, which has traditionally been considered unsuitable for long-term storage due to significant deterioration in flavor, to maintain the texture and adhesiveness of freshly cooked rice for at least 48 hours in temperature environments (4-15°C) such as those found in convenience store and supermarket showcases where rice balls and boxed lunches are displayed, or in commercial or home refrigerators. This effectively solves conventional problems such as hardening, stickiness, and deterioration in flavor over time. Furthermore, the technology of the present invention is extremely useful not only for home rice cooking, but also for commercial rice cooking, boxed lunches, prepared food, school lunches, and the restaurant industry, which require large-scale cooking and long-term storage, significantly contributing to the stable use of rice and satisfying flavor. [Brief explanation of the drawings]

[0031] Figure 1 shows the hardness of Calrose rice. Figure 2 shows the hardness of old rice. Figure 3 shows the adhesion of Calrose to rice. Figure 4 shows the adhesion of old rice.

Claims

1. Sodium lactate and Na ｎ H ２ P ｎ O ３ｎ＋１ A quality improver for cooked rice, comprising sodium metaphosphate represented by the formula:

2. The quality improver for cooked rice according to claim 1, characterized in that the amount of sodium lactate added is 0.01% by mass to 10% by mass, preferably 0.05% by mass to 5% by mass, more preferably 0.1% by mass, relative to the mass of raw rice, and the amount of sodium metaphosphate added is 0.01% by mass to 10% by mass, preferably 0.05% by mass to 5% by mass, more preferably 0.1% by mass, relative to the mass of raw rice.

3. Na ｎ H ２ P ｎ O ３ｎ＋１ The quality improver for cooked rice according to claim 1 or 2, characterized in that n≧14, preferably n≧20, of the sodium metaphosphate represented by the formula:

Images