A method for increasing the content of polyphenols and gaba in germinated brown rice

Abstract

The application discloses a method for increasing the content of polyphenols and GABA in germinated brown rice, and uses brown rice as raw material, and comprises the following steps: screening brown rice with complete kernels, cleaning and disinfecting the brown rice, placing the brown rice into a brassinolide solution, activating relevant enzyme activity by ultrasonic treatment, soaking the brown rice after ultrasonic treatment in the brassinolide solution, spraying an ascorbic acid solution to continue germination, synchronously enriching polyphenols and GABA, and finally, after ultraviolet sterilization of the germinated brown rice, drying the germinated brown rice by hot air. The prepared germinated brown rice has synchronous increase in the content of polyphenols and GABA, and the antioxidant capacity is significantly improved, the germination time is shorter, and the sprout length is moderate.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of deep processing of agricultural products, and particularly relates to a method for increasing the contents of polyphenols and GABA in germinated brown rice. BACKGROUND

[0002] Brown rice is a whole grain obtained by retaining the outer layer of rice after hulling, and has more bioactive substances than milled rice. However, traditional brown rice has poor taste, is difficult to cook, and some of the nutritional components are difficult to be efficiently absorbed and utilized by the human body.

[0003] Germinated brown rice is obtained by germinating brown rice under specific conditions to improve its nutritional value and functional properties. During the germination process, enzymes in brown rice are activated, promoting a series of biochemical reactions, which significantly increase the contents of bioactive substances such as gamma-aminobutyric acid (GABA), polyphenols, flavonoids, etc. in brown rice. GABA is a naturally occurring non-protein small molecule functional amino acid, which is an important nerve inhibitor in the nervous system of mammals, and has functions such as lowering blood pressure, regulating hormone secretion, anti-anxiety, and anti-arrhythmia. Phenolic substances are an important antioxidant component, which can scavenge free radicals, reduce oxidative stress, and protect biological macromolecules or cells from potential damage. Therefore, the enrichment of the above-mentioned bioactive substances can greatly improve the nutritional value of germinated brown rice.

[0004] At present, the stress germination of brown rice is mostly single stress germination, and the method of using two or more stresses is less. The existing stress germination method of brown rice cannot effectively solve the problems of long germination period and low germination rate during the preparation of germinated brown rice, especially the problem of asynchronous enrichment of secondary metabolites such as GABA and polyphenols.

[0005] In view of the many advantages of germinated brown rice, it is of great significance to further explore how to optimize the germination process to prepare germinated brown rice with high content of polyphenols and GABA, so as to further improve its nutritional value and health efficacy. SUMMARY

[0006] The existing method for preparing germinated brown rice has problems such as long germination period, poor enrichment effect of active substances such as polyphenols and GABA, and asynchronous enrichment. In view of the above problems, the purpose of the present application is to provide a method for increasing the contents of polyphenols and GABA in germinated brown rice by combining plant growth hormones with ultrasonic pretreatment and ascorbic acid stress germination, so as to realize the synchronous enrichment of GABA and polyphenols and overcome the shortcomings of the existing stress germination method.

[0007] In order to achieve the above purpose, the present application provides a method for increasing the contents of GABA and polyphenols in germinated brown rice, which specifically comprises the following steps:

[0008] S1. The brown rice is subjected to impurity removal, disinfection and washing in sequence, and the treated brown rice is soaked in brassinolide solution to obtain pre-germinated brown rice.

[0009] S2. Spray the pre-germinated brown rice treated in step S2 with ascorbic acid solution and allow it to germinate for 24-40 hours.

[0010] S3. The germinated brown rice treated in step S3 is sterilized and dried using ultraviolet light to obtain germinated brown rice with high polyphenol and GABA content.

[0011] In one embodiment of the present invention, in step S1, the disinfection involves soaking the impurity-removed brown rice in a sodium hypochlorite solution with a concentration of 0.1-1% for 10-30 minutes, then removing it after disinfection and rinsing it repeatedly with tap water.

[0012] In one embodiment of the present invention, in step S1, before soaking, the mixture of brown rice and brassinolide solution is first subjected to ultrasonic treatment, and then soaking treatment is performed after ultrasonic treatment.

[0013] In one embodiment of the present invention, the ultrasonic treatment temperature is 25~35℃, the ultrasonic power is 50~200Hz, and the ultrasonic time is 10~30min.

[0014] In one embodiment of the present invention, in step S1, the concentration of the brassinolide solution is 3~6 μmol / L.

[0015] In one embodiment of the present invention, in step S1, the soaking time is 8-12 hours, the soaking temperature is 25-35°C, and the temperature during soaking is 25-35°C.

[0016] In one embodiment of the present invention, in step S2, the concentration of ascorbic acid used for spraying is 10~40mM.

[0017] In one embodiment of the present invention, in step S2, spraying is performed once every 2 hours for 1 to 2 minutes each time.

[0018] In one embodiment of the present invention, in step S2, the ambient temperature of the spray treatment is 25°C to 35°C.

[0019] In one embodiment of the present invention, in step S3, the ultraviolet light is emitted by an ultraviolet lamp with a power of 15W.

[0020] In one embodiment of the present invention, in step S3, during ultraviolet sterilization, the light source is 30-70 cm away from the pre-germinated brown rice, and the irradiation time is 1-5 min.

[0021] In one embodiment of the present invention, in step S3, the drying temperature is 40~50℃ and the drying wind speed is 1~4m / s.

[0022] The present invention also discloses a germinated brown rice obtained by the above method.

[0023] The present invention also discloses an application of the above-mentioned germinated brown rice in the food industry.

[0024] The beneficial effects of this invention are:

[0025] (1) Brassinolide is a novel, green, and environmentally friendly plant growth regulator that is widely present in plants. It can increase the potential difference of cell membranes and the activity of ATPases, while also enhancing the effects of other auxins. Even at trace concentrations, it can significantly promote the vegetative growth of plants, induce germination, and enrich nutrients. Ascorbic acid is readily soluble in water and has strong reducing properties. It can enter the cell through active transport and simple absorption, providing a weakly acidic and reducing environment conducive to the enrichment of polyphenols and GABA in brown rice germination.

[0026] (2) By first soaking the sterilized brown rice in brassinolide solution, and then using ascorbic acid stress to enrich the nutrients in the germinated brown rice, the content of polyphenols and GABA in the germinated brown rice can be significantly increased.

[0027] (3) Ultrasonic treatment of the mixture of brown rice and brassinolide solution in the early stage of soaking brown rice helps to further enrich the nutrients in brown rice. The total phenol content in brown rice treated by the method of the present invention can be as high as 240.14 mg GAE / gDW, and the GABA content can be as high as 55.64 mg / 100gDW.

[0028] (4) Gamma-aminobutyric acid (GABA) has physiological activities such as promoting blood circulation, enhancing brain cell metabolism, calming the nerves, and improving liver and kidney function. Plant phenolic substances have the effects of scavenging free radicals, anti-oxidation, and anti-aging. These are all important nutrients for the human body. This invention utilizes a method of ultrasound and plant hormone induction combined with oxidative stress to synergistically increase the content of GABA and total phenols in germinated brown rice, and can also improve the antioxidant capacity of germinated brown rice, increase the added value of rice, and improve people's comprehensive utilization of rice.

[0029] (5) The processing time of the method of the present invention is relatively simple and efficient, and the resulting brown rice has high nutritional value. Attached Figure Description

[0030] Figure 1 The morphology of germinated brown rice in Examples 1-5 and Comparative Examples 1-4 is shown. Detailed Implementation

[0031] The specific embodiments of the present invention are further described below, but the scope of protection of the present invention is not limited to the scope described in the embodiments. Unless otherwise specified, the various raw materials, production equipment, testing methods and testing equipment used in the following embodiments are all commonly used in the art, and the brown rice used in the following embodiments and comparative examples is from the same batch of japonica rice.

[0032] (I) Determination of polyphenol-related indicators

[0033] (1) Determination of free and bound phenols: Take 200 μL of the extract sample, add 800 μL of ultrapure water and 200 μL of Folin-Ciocalteu reagent, incubate the mixture for 6 min, then add 1.8 mL of deionized water and 2 mL of 7% NaCO3 solution, vortex mix, and react at room temperature in the dark for 90 min. Measure the absorbance at 760 nm. Using gallic acid (GAE) as the standard, the regression equation of the standard curve was obtained. The total phenol content is expressed as the equivalent of mg gallic acid per 100 g dry weight of the sample (mgGAE / 100 g DW).

[0034] (2) Phenylalanine ammonia-lyase activity assay: Weigh 0.5 g of germinated brown rice flour, add 5 mL of 0.1 mol / L borate-borax buffer (containing 2 mmol / L EDTA and 5 mmol / L mercaptoethanol), grind in an ice bath for 1 min, centrifuge at 8000×g for 10 min at 4℃, take 0.5 mL of supernatant (enzyme extract), add 3 mL of 50 mmol / L pH 8.8 borate buffer, incubate at 37℃ for 5 min, add 0.5 mL of 20 mmol / L L-phenylalanine solution, and incubate again at 37℃ for 1 h. Immediately after incubation, add 0.1 mL of 6 mol / L HCl solution to terminate the reaction, and measure the OD value at a wavelength of 290 nm. One PAL activity unit (U) is defined as a change in absorbance of the enzyme-catalyzed reaction system of 0.01 per hour. The enzyme extract was inactivated by boiling for 15 min as a control.

[0035] (II) Determination of GABA-related indicators

[0036] (1) Determination of glutamate decarboxylase activity: Weigh 1.0 g of brown rice sample, add 5.0 mL of phosphate buffer (pH 5.8) at 4℃, grind into a homogenate, transfer to a centrifuge tube, and centrifuge at 4℃ and 10000 r / min for 15 min. The supernatant is the crude enzyme extract. Take 1.0 mL of substrate solution (1% sodium glutamate solution, pH 5.8) and 1 mL of crude enzyme solution and react in a 40°C water bath for 2 h. The amount of GABA generated is determined by colorimetric method at a wavelength of 645 nm. One GAD activity unit (U) is defined as an increase of 0.01 absorbance value per gram of germinated brown rice (fresh weight) per minute in the enzymatic reaction system, expressed as 0.01 OD645 / (min·g), i.e., U / g FW.

[0037] (2) Determination of GABA content: 1.000 g of germinated brown rice flour was weighed into a 10 mL centrifuge tube for each sample, and 5 mL of deionized water was added. The mixture was extracted by shaking on a shaker for 2 h (30℃, 150 r / min), then centrifuged at 4000 r / min for 5 min, and filtered through medium-speed quantitative filter paper. 0.5 mL of the supernatant was taken, and 0.2 mL of 0.2 mol / L borate buffer (pH=9.0), 1 mL of 6% phenol, and 0.4 mL of 9% NaClO were added. After vigorous shaking, the mixture was placed in boiling water for 10 min, then placed in an ice bath for 20 min, and continued shaking until a blue color appeared. Finally, 2 mL of 60% ethanol was added to the mixture, and after mixing, the mixture was filtered through a 0.22 μm pinhole filter. The sample was analyzed by UV-Vis spectrophotometer at a wavelength of 645 nm. Using 0.5 mL of standard solutions with concentrations of 0.00, 0.04, 0.08, 0.12, 0.16, and 0.20 mg / mL, the absorbance was measured according to the method described above. A regression equation was established with GABA content as the abscissa (x) and absorbance as the ordinate (y), and a standard curve was plotted.

[0038] (III) Determination of antioxidant capacity

[0039] (1) Determination of DPPH antioxidant capacity: 0.1 mL of the extract sample was mixed with 3.9 mL of DPPH solution (0.03 mg / mL), and incubated for 30 min in the dark. The absorbance was measured at 517 nm using a spectrophotometer. The DPPH free radical scavenging rate was calculated according to the formula:

[0040] DPPH free radical scavenging rate (%) = [(A0-A0)] s )] / A0×100

[0041] A sA0 represents the absorbance of the sample, and A0 represents the absorbance of the blank control. A standard curve was obtained using Trolox as the standard.

[0042] The antioxidant capacity results are converted into the equivalent of μmol of water-soluble vitamin E per 1 g of dry sample (µmolTE / g DW).

[0043] (2) Determination of the antioxidant capacity of ABTS: An ABTS+ stock solution was prepared by mixing 7 mmol ABTS and 4.95 mmol potassium persulfate in equal volumes and incubating at 4°C in the dark for 12–16 h. The stock solution was then diluted to achieve an absorbance of 0.70 ± 0.02 at 734 nm. 0.1 mL of brown rice polyphenol extract was mixed with 3.9 mL of the prepared ABTS+ solution and incubated for 10 min in the dark. The absorbance at 734 nm was recorded. The ABTS free radical scavenging rate was calculated using the formula:

[0044] ABTS free radical scavenging rate (%) = [(A0-A0)] s )] / A0×100

[0045] A s A0 represents the absorbance of the sample, and A0 represents the absorbance of the blank control. A standard curve was obtained using Trolox as the standard.

[0046] The antioxidant capacity results are converted into the equivalent of μmol of water-soluble vitamin E per 1 g of sample dry weight (µmol TE / g DW).

[0047] Example 1

[0048] A method for increasing the polyphenol and GABA content in germinated brown rice includes the following steps:

[0049] S1. Collect whole rice grains as raw material for germination. Wash the raw material, disinfect it with 0.1% sodium hypochlorite solution for 20 minutes, and then rinse it repeatedly with tap water.

[0050] S2. The sterilized brown rice was soaked in a 3 μmol / L brassinolide solution and treated with ultrasound at 30℃ and 100W for 20 min. Then it was placed in a 30℃ constant temperature incubator for 10 h to obtain pre-germinated brown rice.

[0051] S3. In a 30℃ constant temperature incubator, spray with 15 mM ascorbic acid every 2 hours for 2 minutes each time. The pre-germinated brown rice treated in step S2 germinated for 36 hours to obtain germinated brown rice.

[0052] S4. The germinated brown rice is sterilized by ultraviolet irradiation. It is treated by irradiating with an ultraviolet lamp (15 W) at a distance of 50 cm for 3 minutes, and then dried with hot air at 50℃ for 4 hours with a wind speed of 1.5 m / s to obtain the germinated brown rice product with high phenolic acid and high GABA.

[0053] Example 2

[0054] A method for increasing the polyphenol and GABA content in germinated brown rice includes the following steps:

[0055] S1. Collect whole rice grains as brown rice raw material for germination. Wash the brown rice raw material, disinfect it with 0.1% sodium hypochlorite solution for 20 minutes, and then rinse it repeatedly with tap water.

[0056] S2. The sterilized brown rice was soaked in a 6 μmol / L brassinolide solution and treated with ultrasound at 30℃ and 100W for 30 min. Then it was placed in a 30℃ constant temperature incubator for 10 h to obtain pre-germinated brown rice.

[0057] S3. In a 30℃ constant temperature incubator, 5mM ascorbic acid is sprayed on the brown rice treated in steps S1 and S2 every 2 hours, and germinated brown rice is obtained after 36 hours of germination.

[0058] S4. The germinated brown rice is sterilized by ultraviolet irradiation. It is treated by irradiating with an ultraviolet lamp (15 W) at a distance of 50 cm for 3 minutes, and then dried with hot air at 50℃ for 4 hours at a wind speed of 1.5 m / s to obtain the germinated brown rice product with high phenolic acid and high GABA.

[0059] Example 3

[0060] A method for increasing the polyphenol and GABA content in germinated brown rice includes the following steps:

[0061] S1. Collect whole rice grains as brown rice raw material for germination. Wash the brown rice raw material, disinfect it with 0.1% sodium hypochlorite solution for 20 minutes, and then rinse it repeatedly with tap water.

[0062] S2. The sterilized brown rice was soaked in a 6 μmol / L brassinolide solution and treated with ultrasound at 30℃ and 100W for 30 min. Then it was placed in a 30℃ constant temperature incubator for 10 h to obtain pre-germinated brown rice.

[0063] S3. In a 30℃ constant temperature incubator, 10mM ascorbic acid is sprayed on the brown rice treated in steps S1 and S2 every 2 hours, and the germinated brown rice is obtained after 36 hours of germination.

[0064] S4. The germinated brown rice is sterilized by ultraviolet irradiation. It is treated by irradiating with an ultraviolet lamp (15 W) at a distance of 50 cm for 3 minutes, and then dried with hot air at 50℃ for 4 hours at a wind speed of 1.5 m / s to obtain the germinated brown rice product with high phenolic acid and high GABA.

[0065] Example 4

[0066] A method for increasing the polyphenol and GABA content in germinated brown rice includes the following steps:

[0067] S1. Collect whole rice grains as brown rice raw material for germination. Wash the brown rice raw material, disinfect it with 0.1% sodium hypochlorite solution for 20 minutes, and then rinse it repeatedly with tap water.

[0068] S2. The sterilized brown rice was soaked in a 6 μmol / L brassinolide solution and treated with ultrasound at 30℃ and 100W for 30 min. Then it was placed in a 30℃ constant temperature incubator for 10 h to obtain pre-germinated brown rice.

[0069] S3. In a 30℃ constant temperature incubator, the brown rice treated in steps S1 and S2 was sprayed with 15mM ascorbic acid every 2 hours, and germinated brown rice was obtained after 36 hours of germination.

[0070] S4. The germinated brown rice is sterilized by ultraviolet irradiation. It is treated by irradiating with an ultraviolet lamp (15 W) at a distance of 50 cm for 3 minutes, and then dried with hot air at 50℃ for 4 hours at a wind speed of 1.5 m / s to obtain the germinated brown rice product with high phenolic acid and high GABA.

[0071] Example 5

[0072] A method for increasing the polyphenol and GABA content in germinated brown rice includes the following steps:

[0073] S1. Collect whole rice grains as brown rice raw material for germination. Wash the brown rice raw material, disinfect it with 0.1% sodium hypochlorite solution for 20 minutes, and then rinse it repeatedly with tap water.

[0074] S2. The sterilized brown rice was soaked in a 6 μmol / L brassinolide solution and treated with ultrasound at 30℃ and 100W for 30 min. Then it was placed in a 30℃ constant temperature incubator for 10 h to obtain pre-germinated brown rice.

[0075] S3. In a 30℃ constant temperature incubator, the brown rice treated in steps S1 and S2 was sprayed with 20mM ascorbic acid every 2 hours, and germinated brown rice was obtained after 36 hours of germination.

[0076] S4. The germinated brown rice is sterilized by ultraviolet irradiation. It is treated by irradiating with an ultraviolet lamp (15 W) at a distance of 50 cm for 3 minutes, and then dried with hot air at 50℃ for 4 hours at a wind speed of 1.5 m / s to obtain the germinated brown rice product with high phenolic acid and high GABA.

[0077] Example 6

[0078] A method for increasing the polyphenol and GABA content in germinated brown rice includes the following steps:

[0079] S1. Collect whole rice grains as brown rice raw material for germination. Wash the brown rice raw material, disinfect it with 0.1% sodium hypochlorite solution for 20 minutes, and then rinse it repeatedly with tap water.

[0080] S2. The sterilized brown rice was soaked in a 6 μmol / L brassinolide solution, and then placed directly into a 30℃ constant temperature incubator for 10 h without ultrasonic treatment to obtain pre-germinated brown rice.

[0081] S3. In a 30℃ constant temperature incubator, the brown rice treated in steps S1 and S2 was sprayed with 15mM ascorbic acid every 2 hours, and germinated brown rice was obtained after 36 hours of germination.

[0082] S4. The germinated brown rice is sterilized by ultraviolet irradiation. It is treated by irradiating with an ultraviolet lamp (15 W) at a distance of 50 cm for 3 minutes, and then dried with hot air at 50℃ for 4 hours at a wind speed of 1.5 m / s to obtain the germinated brown rice product with high phenolic acid and high GABA.

[0083] Comparative Example 1

[0084] A method for preparing germinated brown rice, which is the same as in Example 1 except that the brassinolide solution in step S2 is replaced with ultrapure water for soaking.

[0085] Comparative Example 2

[0086] A method for preparing germinated brown rice, which is the same as in Example 1 except that the ascorbic acid in step S3 is replaced by ultrapure water instead of spraying.

[0087] Comparative Example 3

[0088] A method for preparing germinated brown rice is the same as in Example 1, except that in steps S2 and S3, the solutions used for soaking and spraying are replaced with ultrapure water.

[0089] Comparative Example 4

[0090] A method for preparing brown rice involves collecting rice grains with intact germs as raw materials for germination, and directly measuring various indicators without germination treatment.

[0091] Comparative Example 5

[0092] A method for preparing germinated brown rice, which is the same as in Example 1 except that the brassinolide solution in step S2 is replaced with 0.2 mmol of gibberellin.

[0093] Comparative Example 6

[0094] A method for preparing germinated brown rice is the same as in Example 1, except that the order of the brassinolide solution in step S2 and the ascorbic acid solution in step S3 is changed. First, the rice is soaked in ascorbic acid solution, and then it is sprayed with brassinolide solution.

[0095] Comparative Example 7

[0096] A method for preparing germinated brown rice, which is the same as Comparative Example 2 except that in step S2, a 9 μmol / L brassinolide solution is used for soaking.

[0097] Comparative Example 8

[0098] A method for preparing germinated brown rice, which is the same as in Example 1 except that the ascorbic acid spraying in step S3 is replaced with a soaking solution.

[0099] The results of the determination of polyphenol content and related enzyme activity in the prepared germinated brown rice are shown in Table 1.

[0100] Table 1. Determination of polyphenol content and related enzyme activity in different germinated brown rice varieties.

[0101]

[0102] As shown in Table 1, the ungerminated brown rice in Comparative Example 4 contained very little polyphenols, while the total phenolic acid content of the germinated brown rice prepared under stress treatment in Examples 1-5 was significantly increased (p<0.05). The total phenolic content of the germinated brown rice prepared in Example 2 was higher than that in Example 1. This is because the brown rice underwent ultrasonic treatment combined with soaking in a 6 μmol / L brassinolide solution during the pre-germination stage. Compared with a 3 μmol / L brassinolide solution, this not only accelerated the absorption of water by the brown rice epidermis but also significantly increased the free water content and water activity in the brown rice. Furthermore, the brassinolide activated the endogenous auxin in the brown rice after entering the cells, which is beneficial to the embryonic growth of the brown rice.

[0103] Pre-germinated brown rice treated with ascorbic acid solution was sprayed with a solution that activated the activity of phenylalanine ammonia-lyase, an endogenous enzyme related to polyphenol synthesis, reaching a maximum of 58.35 ± 1.86 u / g FW, which was 19 times higher than that of ungerminated brown rice. This promoted the synthesis and accumulation of polyphenols in the brown rice, increasing its polyphenol content. In Examples 2-5, the concentration of ascorbic acid solution was gradually increased. On the one hand, the exogenous ascorbic acid solution increased the osmotic pressure, inhibiting the germination of brown rice and inducing oxidative stress; on the other hand, it provided an acidic environment to enhance the activity of related enzymes. The effect was best when the ascorbic acid spraying concentration was 15 mM; excessively high concentrations would excessively inhibit germination. Compared with the single stress germination of Comparative Examples 1-3, the polyphenol content and related enzyme activities of Examples 1-5 were significantly increased, indicating that ultrasonic pretreatment, soaking in brassinolide solution and spraying with ascorbic acid solution have a synergistic effect on the enrichment of polyphenols in germinated brown rice, with the total phenol content reaching a maximum of 240.14±3.47 mgGAE / gDW.

[0104] Table 2. Results of GABA content and related enzyme activities in different germinated brown rice varieties.

[0105]

[0106] Table 2 shows that, compared with Comparative Examples 1-3, the germinated brown rice treated with ultrasound combined with brassinolide and ascorbic acid oxidative stress in Examples 1-5 showed a significant increase in GABA content (p<0.05), with Example 4 being the optimal example. This may be because ultrasound treatment of brown rice activates the relevant metabolic pathways for GABA synthesis in plants. The 6 μmol / L brassinolide, acting as a plant hormone during the soaking stage, activates other auxins, further enhancing germination momentum. Exogenous ascorbic acid provides an acidic environment, enhancing GABA stability and glutamate decarboxylase activity, reducing GABA loss, and maximizing GABA enrichment. In Examples 2-5, the concentration of ascorbic acid spraying gradually increased. In Example 4, a 15 mM ascorbic acid solution spraying resulted in the highest GABA content of 55.64 ± 1.71 mg / 100g DW. Ascorbic acid solutions above 15 mM excessively inhibited brown rice germination, leading to poor enrichment effects.

[0107] Tables 1 and 2 show that, comparing Example 1 and Comparative Example 5, brassinolide, as a novel green plant hormone, can promote the accumulation of polyphenols and GABA during brown rice germination at extremely low concentrations compared to gibberellin, exhibiting advantages such as low dosage and high efficiency. Comparing Examples 1 and 3 with Comparative Example 7, it was found that under the same conditions, a brassinolide soaking solution concentration of 6 μmol / L resulted in the best nutrient accumulation effect in germinated brown rice. Observing Examples 1 and Comparative Example 8, it was found that spraying is more effective than soaking for germinating polyphenols and GABA, as soaking may lead to greater nutrient loss and microbial growth.

[0108] Table 3. Test results of antioxidant capacity indices of different germinated brown rice varieties.

[0109]

[0110] Table 3 shows that the antioxidant activity of germinated brown rice is closely related to the polyphenol content, and the antioxidant capacity of brown rice is significantly improved after germination under combined stress. This invention results in a final germinated brown rice product with good antioxidant properties.

[0111] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for increasing the GABA and polyphenol content in germinated brown rice, characterized in that, Specifically, the following steps are included: S1. The brown rice is subjected to impurity removal, disinfection and washing in sequence, and the treated brown rice is soaked in brassinolide solution to obtain pre-germinated brown rice. The concentration of brassinolide solution is 3~6μmol / L. S2. Spray the pre-germinated brown rice treated in step S2 with ascorbic acid solution and allow it to germinate for 24-40 hours. The concentration of ascorbic acid is 10-20 mM. S3. The germinated brown rice treated in step S3 is sterilized and dried using ultraviolet light to obtain germinated brown rice with high polyphenol and GABA content.

2. The method according to claim 1, characterized in that, In step S1, before soaking, the mixture of brown rice and brassinolide solution is first ultrasonically treated, and then soaked.

3. The method according to claim 1 or 2, characterized in that, In step S1, the disinfection involves soaking the cleaned brown rice in a 0.1-1% sodium hypochlorite solution for 10-30 minutes, then removing it and rinsing it repeatedly with tap water.

4. The method according to claim 2, characterized in that, The ultrasonic treatment is performed at a temperature of 25-35°C, with an ultrasonic power of 50-200Hz and an ultrasonic time of 10-30 minutes.

5. The method according to claim 1 or 2, characterized in that, In step S1, the soaking time is 8~12h, the soaking temperature is 25~35℃, and the soaking temperature is 25~35℃.

6. The method according to claim 1 or 2, characterized in that, In step S2, spraying is performed once every 2 hours for 1 to 2 minutes each time, and the ambient temperature for spraying is 25℃ to 35℃.

7. The method according to claim 1 or 2, characterized in that, In step S3, the ultraviolet light is emitted by an ultraviolet lamp with a power of 15W. During ultraviolet sterilization, the light source is 30-70cm away from the pre-germinated brown rice, and the irradiation time is 1-5min.

8. The method according to claim 1 or 2, characterized in that, In step S3, the drying temperature is 40~50℃ and the drying wind speed is 1~4m / s.

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