Preparation method of germinated rice rich in gamma-aminobutyric acid and product thereof

Abstract

The invention relates to the technical field of food processing, and particularly provides a preparation method of germinated rice rich in gamma-aminobutyric acid and a product thereof. The method aims at solving the problem that an existing method for preparing gamma-aminobutyric acid through a rice enrichment method does not have universality. According to the method, ten different rice germplasms are adopted as research materials, and a germination condition which not only can efficiently enrich GABA but also has universality is explored by controlling the germination temperature, the germination time and the pH value of a soaking solution. Meanwhile, the GABA content of 225 parts of rice core germplasm material grains is measured based on the germination condition provided by the invention, and the GABA content is mainly concentrated in a range of 3-15mg / 100g and accords with normal distribution, so that the GABA content measured by the method has relatively high reliability, can be used for subsequent research, and has a good application prospect. On the basis, the correlation between the GABA content and the brown rice form and the rice embryo character is analyzed, and material and theoretical support is provided for seed quality creation and variety breeding of rice rich in GABA functions.

Description

Technical Field

[0001] The invention belongs to the field of food processing and relates to a preparation method of germinated rice rich in gamma-aminobutyric acid and a product thereof. Background Art

[0002] γ-aminobutyric acid (GABA) is a non-protein amino acid that is widely found in microorganisms, plants and animals, such as seeds, rhizomes and tissues of leguminous plants, ginseng plants and Chinese herbal medicines. It is found in nerve tissues in the human body. It is reported that γ-aminobutyric acid has multiple biological activities and plays an important role in protecting the nervous system and preventing related diseases, such as anti-hypertension, anti-diabetes, anti-oxidation, anti-inflammatory, anti-bacterial, anti-allergic, liver protection, kidney protection, intestinal protection, etc. At the same time, studies have shown that GABA can activate GABA A The receptors reduce the activity of brain cells and promote sleep. Therefore, the development of foods or health products rich in GABA has become a hot topic. Rice is the main food source for more than half of the world's population, and the cultivation of functional rice rich in GABA has received great attention from the rice breeding and food processing industries.

[0003] Studies have shown that the content of amino acids and other active substances in germinated brown rice is significantly higher than that in brown rice, and the GABA content is three times that of ungerminated brown rice. The production of GABA in rice grains mainly occurs in the rice embryo. The factors affecting brown rice germination mainly include germination temperature, germination time, and pH of the soaking solution. Kang Wenhan et al. used response surface analysis to optimize the process parameters for enriching GABA by germination of brown rice, and found that the optimal germination temperature was 30°C, the soaking time was 24 h, and the germination time was 28 h (Kang Wenhan, Tian Honglei, Cheng Weidong, Zhan Ping, Wang Jun, Wu Qiang. Research on the optimization of the process of enriching γ-aminobutyric acid by germination of brown rice [J]. Food Industry, 2016, 37(5): 78-82.). Zhang Yingjiao et al. optimized the germination process parameters of Jinchuan red brown rice and found that when the soaking temperature was 25℃, the soaking time was 2 h, the germination time was 48 h, and the germination temperature was 40℃, the GABA content reached 46.3436 mg / 100g (Zhang Yingjiao, Zhu Yongqing, Chen Jian, Xia Chen, Deng Junlin, Li Yanlin, Li Juan, Li Huajia, Liu Pei. Preparation process of Jinchuan germinated red brown rice rich in γ-aminobutyric acid (GABA) [J]. Chinese Food and Nutrition, 2017, 23(8): 45-47). However, the germination conditions explored using one or several rice varieties as research materials have certain limitations. Therefore, it is necessary to explore an optimal germination condition that is suitable for different rice germplasms, provide new insights for the improvement of the GABA enrichment method of germinated brown rice, and also provide a theoretical basis for the subsequent exploration and functional analysis of GABA content control genes through genetic populations. Summary of the invention

[0004] The purpose of the present invention is to provide a universal method for preparing germinated brown rice rich in γ-aminobutyric acid in view of the problem that the existing method for preparing γ-aminobutyric acid by rice enrichment method has certain limitations.

[0005] The present invention provides the following technical solutions: A method for preparing germinated brown rice rich in gamma-aminobutyric acid comprises the following steps: (1) Select complete and full brown rice, rinse it with purified water, soak it in sodium hypochlorite solution for 10 minutes, and then rinse it with deionized water; (2) placing the brown rice treated in step (1) in a beaker containing a phosphate buffer solution with a pH value of 5.5, and soaking it in a constant temperature water bath at 37° C. for 24 h to germinate; (3) After germination, the soaked brown rice was washed with deionized water and spread on a culture dish with filter paper. The culture dish was placed in a constant temperature drying oven and the germination temperature was set to 37°C for 50 h to obtain germinated brown rice.

[0006] Furthermore, in step (3), after the culture dish is placed in a constant temperature drying oven, deionized water is sprayed and the brown rice is turned over every 6 hours to ensure that the brown rice is moist.

[0007] Furthermore, in step (1), the concentration of the sodium hypochlorite solution is 1 v / v%.

[0008] Furthermore, the variety of brown rice includes japonica rice or indica rice.

[0009] The product is obtained according to the preparation method of the germinated brown rice rich in gamma-aminobutyric acid.

[0010] Beneficial effects of the present invention: The present invention uses 10 different rice germplasms as research materials, and explores a germination condition that can not only efficiently enrich GABA but also has universality through the control of germination temperature, time, and pH of the soaking liquid. At the same time, the GABA content of 225 core rice germplasm materials was measured based on the germination conditions provided by the present invention, and it was found that the GABA content was mainly concentrated in the range of 3-15 mg / 100g, and conformed to the normal distribution, indicating that the GABA content measured by this method has high reliability and can be used for subsequent research, and based on this, the correlation between GABA content and brown rice morphology and rice embryo traits was analyzed, which provides materials and theoretical support for the creation of GABA-rich functional rice germplasm and variety breeding. In addition, the GABA content in the rice material Jefferson is as high as 39.24 mg / 100g, reaching the leading level of similar methods at home and abroad. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Effect of different germination time on GABA content.

[0012] Figure 2 Effects of different germination temperatures on GABA content. Note: Values ​​are mean ± standard deviation. P The values ​​were obtained through one-way ANOVA, * indicates P The difference was significant at the <0.05 level, ** indicates P The difference was extremely significant at the <0.01 level.

[0013] Figure 3 Effects of different pH soaking solutions on GABA content. Note: Values ​​are mean ± standard deviation. P The values ​​were obtained through one-way ANOVA, * indicates P The difference was significant at the <0.05 level, ** indicates P The difference was extremely significant at the <0.01 level.

[0014] Figure 4 Frequency distribution of GABA content in germinated brown rice from 225 rice materials.

[0015] Figure 5 Heat map of the correlation analysis between GABA content and brown rice morphology and rice embryo traits. Note: The color represents the correlation coefficient, red represents positive correlation and blue represents negative correlation. DETAILED DESCRIPTION

[0016] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0017] Materials and reagents: The research team independently collected 225 core rice germplasms, including 89 japonica rice materials and 136 indica rice materials. The experimental materials were planted in the Fuyang Base of the China National Rice Research Institute in Hangzhou in May 2022 and were managed conventionally.

[0018] Example 1 Screening and optimization of GABA enrichment conditions 1. Treatment of Brown Rice at Different Germination Times (1) Five indica and japonica rice materials were randomly selected from 225 rice germplasm resources, each with five biological replicates and 2 g per replicate. The whole and plump brown rice was selected, rinsed with purified water, then immersed in 1 v / v% sodium hypochlorite solution for 10 min for disinfection, and then rinsed with deionized water. (2) placing the brown rice treated in step (1) in a beaker containing a phosphate buffer solution with a pH of 5.5, and soaking it in a constant temperature water bath at 37° C. for 24 h to germinate; (3) After germination, the soaked brown rice was washed with deionized water and spread on a Petri dish with filter paper. The Petri dish was placed in a 37°C constant temperature drying oven for 14, 26, 38, 50 and 62 h. After germination, the rice was dried and the GABA content in the brown rice at different germination times was measured. During the germination process, a certain amount of deionized water was sprayed every 6 h and the brown rice was turned over to ensure that the brown rice was moist.

[0019] Experimental results: Within 0-50 h, as the germination time prolonged, the GABA content showed an upward trend; within 50-62 h, as the germination time continued to prolong, the GABA content showed a downward trend. Among them, except Xiushui 110, the GABA content of other varieties reached the highest at 50 h of germination, among which the highest GABA content was Aizizhan, reaching 37.76 mg / 100g at 50 h. The results showed that the optimal germination time for different rice germplasms was 50 h.

[0020] 2. Different germination temperature treatment of brown rice (1) Randomly select 5 indica rice and 5 japonica rice materials from 225 rice germplasm resources, select complete and plump brown rice, rinse with purified water, soak and disinfect in 1v / v% sodium hypochlorite solution for 10 min, and then rinse with deionized water; (2) placing the brown rice treated in step (1) in a beaker containing a phosphate buffer solution with a pH of 5.5, and soaking it in a constant temperature water bath at 37° C. for 24 h to germinate; (3) After germination, the soaked brown rice was washed with deionized water and spread on a Petri dish with filter paper. The Petri dish was placed at different temperatures (25°C, 37°C, 42°C) for germination for 24 h. Each material had 5 replicates under each temperature treatment, with 2 g per replicate. After germination, the brown rice was dried and the GABA content in the brown rice was measured at different germination times. During the germination process, a certain amount of deionized water was sprayed every 6 h and the brown rice was turned over to ensure that the brown rice was moist.

[0021] Experimental results: GABA content of the above 10 materials was measured at different germination temperatures ( Figure 2), the results showed that the GABA content of all materials increased significantly after germination. Except for Xiushui 110, which reached the highest GABA content at 25℃, the GABA content of other varieties reached the highest at 37℃. Among them, Songjing 2 had the highest GABA content at 37℃, reaching 13.28 mg / 100g, and the difference in GABA content between germinated brown rice and brown rice was the most significant, reaching 30 times; IRAT109, Chujing 40, Qiutian 39, Kasalath, Aizaizhan and Xiangzaoxian 31 had extremely significant differences compared with ungerminated brown rice at 37℃, which were 4.0, 5.1, 17.5, 4.8, 8.0 and 16.6 times respectively; Gui 99 and Mianhui 725 had significant differences compared with ungerminated brown rice, and the GABA content in germinated brown rice was 2.2 and 2.3 times that in brown rice. Therefore, the optimal germination temperature for different rice germplasms was 37°C.

[0022] 3. Treatment of brown rice with different pH soaking solutions (1) Randomly select 5 indica rice and 5 japonica rice materials from 225 rice germplasm resources, select complete and plump brown rice, rinse with purified water, soak and disinfect in 1v / v% sodium hypochlorite solution for 10 min, and then rinse with deionized water; (2) Prepare phosphate buffer with an ion concentration of 0.1 mol / L and pH = 5.0, 5.5, and 6.0, and place the brown rice treated in step (1) in a beaker containing phosphate buffer solutions of different pH values. Each material has 5 replicates at each pH value, and each replicate has 2 g. The rice is placed in a constant temperature water bath at 37°C for 24 h to germinate. (3) After germination, the soaked brown rice was washed with deionized water and spread on a Petri dish with filter paper. The Petri dish was placed at 37°C for germination for 24 h. After germination, the rice was dried and the GABA content in the brown rice at different germination times was measured. During the germination process, a certain amount of deionized water was sprayed every 6 h and the brown rice was turned over to ensure that the brown rice was moist.

[0023] Experimental results: GABA content of the above 10 materials was determined at different pH values ​​of the soaking solution ( Figure 3), except Xiushui 110, Chujing 40 and Aizaizhan, which had differences under three different pH soaking solutions but did not reach significant differences, the GABA content of the other seven materials reached the highest when the soaking solution pH was 5.5, among which Songjing 2, Gui 99 and Kasalath reached extremely significant differences compared with other pH conditions. Songjing 2 had the highest GABA content at soaking solution pH=5.5, reaching 8.65 mg / 100g, which was 2 times that of soaking solution pH=5.0 and 1.6 times that of soaking solution pH=6.0; Kasalath had extremely significant differences in GABA content under three pH conditions, and its GABA content at soaking solution pH=5.5 was 2.8 times that of soaking solution pH=5.0 and 2.1 times that of soaking solution pH=6.0; IRAT109, Qiutian 39, Xiangzaoxian 31 and Mianhui 725 all had significant differences at soaking solution pH=5.5 compared with other conditions. The results showed that the optimal soaking solution pH for different rice germplasms was 5.5.

[0024] Example 2 Analysis of GABA content differences between different rice germplasm resources The germination conditions studied in Example 1 (temperature of 37°C, time of 50 h, pH of the soaking solution of 5.5) were used to conduct germination experiments on 225 materials, and the GABA content was determined and analyzed. It was found that the GABA content showed significant variation, ranging from 0.49 to 39.24 mg / 100g ( Figure 4 ), the coefficient of variation (CV) was 68.79%, the highest GABA content was in Jefferson, reaching 39.24 mg / 100g, the lowest GABA content was in Pei'ai 64, at 0.49 mg / 100g, the average was 9.11 mg / 100g, and the content of most varieties was concentrated in 3~15 mg / 100g, and a few varieties exceeded 30 mg / 100g. The ten rice varieties with the highest GABA contents measured by this method were Jefferson, GIZA178, Suishashani, KON SUITO5, WIR 1021, C101A51 (Pi2), Taitougu, Jamac, Jia 45, and Liantangzao, consisting of eight indica rice varieties and two japonica rice varieties. The ten rice varieties with the lowest GABA contents were Sunbonnet, Yugu, Xindao 11, Longjing 21, Gumei 4, Zhongzhe B, Erjiuqing, Zhong R8006, Zhongjian 2, and Pei'ai 64, consisting of eight indica rice varieties and two japonica rice varieties (Table 1).

[0025] Table 1 The 20 rice varieties with the highest and lowest GABA contents

[0026] Example 3 Correlation analysis between GABA content in germinated brown rice and grain-related traits and embryo weight ratio For 10 rice varieties with significant differences in GABA content in germinated brown rice, correlation analysis was performed with their brown rice morphology and rice embryo traits. The results showed that GABA content showed extremely significant positive correlation with relative embryo weight of brown rice, brown rice embryo weight, and relative embryo weight of germinated brown rice. Among them, the relative embryo weight of brown rice had the highest correlation with GABA content, reaching 0.780, and the correlations of the other two traits were 0.590 and 0.640, respectively; it showed positive correlation with grain width, roughness rate, and embryo weight of germinated brown rice, but the correlation was not significant; it showed negative correlation with 1000-grain weight, grain length, and length-to-width ratio. The results showed that germplasm materials with larger relative embryo weight also had higher GABA content ( Figure 5 ).

[0027] Obviously, the above described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, ordinary technicians in this field can make other different forms of changes or modifications without making creative work, which should fall within the scope of invention protection.

Claims

1. A method for preparing germinated brown rice rich in γ-aminobutyric acid, characterized in that: The steps include: (1) Select whole and full brown rice, rinse it with purified water, soak it in sodium hypochlorite solution for 10 min, and then rinse it with deionized water; (2) placing the brown rice treated in step (1) in a beaker containing a phosphate buffer solution with a pH value of 5.5, and soaking it in a constant temperature water bath at 37° C. for 24 h to germinate; (3) After germination, the soaked brown rice was washed with deionized water, and the germinated brown rice was spread on a culture dish with filter paper. The culture dish was placed in a constant temperature drying oven, and the germination temperature was set to 37° C. for 50 h to obtain germinated brown rice.

2. The preparation method according to claim 1, characterized in that: In step (3), after placing the culture dish in a constant temperature drying oven, spray deionized water and turn the brown rice every 6 hours to ensure that the brown rice is moist.

3. The preparation method according to claim 1, characterized in that: In step (1), the concentration of the sodium hypochlorite solution is 1 v / v%.

4. The preparation method according to claim 1, characterized in that: The varieties of the brown rice include japonica rice or indica rice.

5. The product obtained by the preparation method according to any one of claims 1 to 4.

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