Selenium-rich mung bean product with high gamma-aminobutyric acid content and preparation method thereof

Abstract

The invention discloses a selenium-rich mung bean product with high gamma-aminobutyric acid content and a preparation method of the selenium-rich mung bean product. The method comprises the following steps: firstly, soaking mung beans in a selenium-rich solution, and then carrying out microwave treatment to enable the mung beans to be rich in selenium; then, germination is carried out in a low-oxygen environment in combination with acid and salt stress conditions, physiological metabolism is regulated and controlled, and enrichment of gamma-aminobutyric acid, conversion of organic selenium and synthesis of flavonoid components are promoted; and finally, dehydrating and baking the germinated mung beans to prepare the mung bean product rich in gamma-aminobutyric acid and organic selenium. The production process is simple, the content of gamma-aminobutyric acid, organic selenium, vitexin, isovitexin and other flavonoid compounds in the mung beans is remarkably increased through selenium-rich solution soaking and hypoxia combined acid salt stress germination, and the palatability and fragrance are enhanced through a high-temperature baking process after dehydration. The mung bean product disclosed by the invention can be used for producing tea bags for direct brewing and drinking, and can also be prepared into powder to serve as a functional food ingredient, so that the requirements of consumers on healthy foods are met.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and particularly relates to a high γ-aminobutyric acid and selenium-rich mung bean product and a preparation method thereof. Background Art

[0002] Mung bean is a small and green seed in leguminous plants, widely distributed in various regions of the world and has been used for more than 3500 years around the world. According to the "Compendium of Materia Medica", mung bean has the effects of clearing heat and removing dampness, detoxifying, promoting diuresis, etc., belonging to the crops of both medicine and food, and is widely used in the food, brewing and pharmaceutical industries, etc. Mung bean is rich in essential nutrients such as protein and starch, and also contains a variety of bioactive substances, such as phenolic acids, flavonoids and γ-aminobutyric acid (GABA), with potential health benefits, including physiological functions such as blood sugar lowering, blood lipid lowering, blood pressure lowering, liver protection, immune regulation and neuroprotective activities. Selenium is an essential micronutrient for the human body and is involved in many physiological and metabolic processes. More than 25 selenoproteins have been found in mammals, which are distributed in different tissues and cells and play an important role in the redox regulation of metabolic processes. The distribution of selenium in nature is uneven, and the selenium content in the soil of different geographical regions varies greatly, resulting in a serious selenium deficiency phenomenon among residents in some parts of China. Human selenium deficiency is related to thyroid dysfunction, irreversible brain damage, vascular diseases, osteoarthropathy, impaired immune response to viral infections, heart diseases and an increased risk of various cancers. The human body cannot synthesize selenium autonomously and needs to be ingested from the outside. Among all the ways of supplementing selenium, dietary selenium supplementation is considered the safest and most effective way. GABA is a four-carbon non-protein amino acid widely present in animals and plants and is a major inhibitory neurotransmitter in the central nervous system. GABA can cause a protective inhibitory state of postsynaptic neurons and is thus used to treat nervous system diseases, and also has the functions of improving memory, spatial cognition, hypothyroidism and cardiovascular diseases. Flavonoids are important secondary metabolites in plants and are the main sources of antioxidants in people's daily diet, with physiological effects such as antioxidant, anti-cancer and antibacterial effects. Ingesting bioactive substances such as GABA and flavonoids from plants is a safe and effective strategy for maintaining good health. Germination can activate the endogenous enzyme activity of plant seeds, cause complex physiological reactions inside the plant seeds, promote the decomposition of macromolecular substances such as proteins into polypeptides and amino acids, improve the nutritional and health value of the seeds, and promote the accumulation of GABA, polyphenols and flavonoid substances. During the seed germination process, the biological transformation of selenium forms can also be effectively carried out to obtain healthy food materials rich in safe organic selenium. Seed germination enhancement is a simple, rapid and effective method for producing selenium-rich foods. Acid stress can activate glutamate decarboxylase (GAD), which is a key enzyme in GABA synthesis. As an organic acid, succinic acid can simulate an acid stress environment by lowering the environmental pH value, thereby potentially increasing the activity of GAD, promoting the accumulation of GABA. Succinic acid also has the potential to inhibit GABA metabolism. When under salt stress, the activity of GAD increases, promoting the conversion of glutamate to GABA. Ammonium acetate is highly soluble in water and is weakly acidic or nearly neutral. As an organic salt, under certain conditions, it may promote seed germination by activating certain physiological pathways. Therefore, developing a high-GABA and selenium-rich mung bean food using a simple and effective biofortification technology has good application and market prospects. Summary of the Invention

[0003] Technical problems to be solved: Selenium cannot be synthesized autonomously in the human body and needs to be supplemented through dietary means. As an important neurotransmitter, GABA has various physiological functions and is also indispensable to the human body. In this invention, by germinating after soaking in a selenium-rich solution and superimposing technical means such as microwave treatment and low-oxygen combined with acid and salt stress germination, the absorption and conversion efficiency of selenium by mung beans is improved, and the accumulation of GABA, polyphenols, and flavonoid substances is promoted. The mung bean products prepared by this invention not only have good palatability, strong aroma, and wide uses, but also contain rich nutrients and have physiological functions such as anti-inflammatory, antioxidant, and memory improvement, meeting the needs of consumers for nutritious and healthy foods. The production process of this invention is simple and has wide uses, which can greatly increase the added value of mung beans.

[0004] Technical solution: A method for preparing a high γ-aminobutyric acid and selenium-rich mung bean product, comprising the following steps: S1. Soaking: Removing impurities, washing mung bean seeds, disinfecting them with 1.0% sodium hypochlorite solution, and soaking the disinfected mung bean seeds in a selenium-rich solution to obtain soaked mung bean seeds; S2. Microwave treatment: Putting the soaked mung bean seeds into a microwave device for microwave treatment; S3. Low-oxygen stress germination: Putting the microwave-treated mung bean seeds into a vacuum drying incubator for low-oxygen vacuum germination; S4. Acid and salt stress germination: Transferring the low-oxygen vacuum germinated mung bean seeds to a constant temperature and humidity incubator for continued germination, spraying succinic acid solution and salt solution on the surface of the mung beans during germination, and obtaining high γ-aminobutyric acid and selenium-rich germinated mung beans after germination; S5. Drying and dehydration: Subjecting the high γ-aminobutyric acid and selenium-rich germinated mung beans to hot air drying and dehydration at 40 - 50 °C for 3 - 12 h; S6. Baking: Baking the dried and dehydrated high γ-aminobutyric acid and selenium-rich germinated mung beans; S7. Preparation of high γ-aminobutyric acid and selenium-rich mung bean products: After the baked high γ-aminobutyric acid and selenium-rich germinated mung beans are cooled to room temperature, they are processed and packaged to obtain the product. Further, in the step S1, the selenium-rich solution is a sodium selenite solution, an amino acid chelated selenium solution or a nano-selenium solution with a concentration of 5-25 mg / L. Further, in the step S1, the soaking temperature is 15-35°C, the time is 2-12 h, and the soaked mung beans are rinsed 2-3 times with drinking water. Further, in the step S2, the conditions for microwave treatment are: the power is 100-300 W, and the time is 10-40 s. Further, in the step S3, the conditions for low-oxygen vacuum germination are: the vacuum degree is 1.1-1.5 kPa, the temperature is 25-30°C, and the time is 5-15 h. Further, in the step S4, the temperature of the constant temperature and humidity incubator is 25-30°C, and the germination time is 3-12 h. Further, in the step S4, the concentration of the succinic acid solution is 2-5 mg / mL, the salt solution is an ammonium acetate solution with a concentration of 0.01-0.05 M, and the specific spraying conditions are: spraying once every 3 h, alternating between the succinic acid solution and the salt solution. Further, in the step S6, the baking conditions are: the temperature is 110-150°C, the time is 10-50 min, and it is turned over 1-2 times every 10 min. Further, the high γ-aminobutyric acid selenium-rich mung bean products include mung bean sprout tea, mung bean sprout tea powder and mung bean sprout powder. Further, after the high γ-aminobutyric acid selenium-rich mung bean sprouts are baked in the step S7 and cooled to room temperature, they are directly vacuum-packed to make bagged mung bean sprout tea. Further, after the high γ-aminobutyric acid selenium-rich mung bean sprouts are baked in the step S7 and cooled to room temperature, they are pulverized by a pulverizer for 5-10 s to 12-30 meshes and then vacuum-packed to obtain mung bean sprout tea powder. Further, after the high γ-aminobutyric acid selenium-rich mung bean sprouts are baked in the step S7 and cooled to room temperature, they are pulverized by a pulverizer for 120-150 s to 120-200 meshes and then vacuum-packed to obtain functional mung bean sprout powder. Beneficial effects: 1. In the mung bean products soaked in the selenium-rich solution of the present invention, the content of organic selenium is increased by 15.64-64 times compared with that of non-selenium-rich mung beans. The effective selenium form biotransformation occurs during seed germination, and the content of organic selenium is increased, achieving the purpose of dietary selenium supplementation. 2. The production steps of the mung bean products of the present invention are simple and no waste is generated during the process. Moreover, these mung bean products have a wide range of uses. They can be directly brewed or used as functional ingredients. They have a strong aroma, good palatability, and high commercial value. 3. The present invention utilizes the hypoxic stress technique. Hypoxic stress inhibits the electron transport chain in plant cells, leading to the decomposition of carbohydrate substances through the glycolytic pathway to generate lactic acid and ethanol, thereby causing changes in cytoplasmic pH. This environment activates glutamate decarboxylase (GAD), which catalyzes the conversion of L-glutamate into GABA. In addition, hypoxic stress also inhibits the aerobic respiration of mung beans, inhibits the activity of γ-aminobutyric acid transaminase, and GABA accumulates; 4. The present invention utilizes the acid and salt stress techniques. Salt stress causes an increase in the ion concentration outside the plant cell membrane, especially the accumulation of Ca 2 +, and Ca 2 + acts as a second messenger to enhance the activity of GAD again. The activity of GAD is mainly manifested in two regulatory levels: pH-dependence and Ca 2 +-dependence. Acid stress can also activate the activities of GAD and diamine oxidase (DAO). The optimal pH of GAD is generally between 5.5 and 6.0. A certain amount of H + is consumed during the synthesis of GABA. Adding acid to lower the pH and supplement H + can enable the already activated enzymes to play a better role. In addition, salt stress also promotes the accumulation of GABA by activating DAO and polyamine oxidase (PAO) in the polyamine degradation pathway to generate the precursor substance 4-hydroxybutanedioic acid; 5. The present invention uses the combined action of hypoxia, acid, and salt stress. Hypoxia activates GAD in the early stage, and acid and salt stress enhance and maintain the activity of GAD again in the later stage. The promoting effects on GABA accumulation will enhance each other. Mung beans enrich GABA through multiple pathways such as activating GABA synthesis, inhibiting metabolism, regulating pH, exerting antioxidant effects, and signal transduction to enhance their adaptability to adversity, significantly improving the germination rate of mung beans and the content of GABA. Flavonoid compounds are also effectively enriched. The main flavonoids are carbon-glycoside flavonoids, mainly vitexin and isovitexin, which have significant anti-tumor, anti-inflammatory, antioxidant, and antidepressant biological functions, can meet the needs of consumers for nutritious and healthy foods, increase the variety of mung bean foods, and improve the added value of mung beans; 6. The present invention uses microwave treatment. Microwaves activate dormant enzymes, promote the decomposition of storage substances, provide energy and nutrients for germination, accelerate the germination process, and promote GABA synthesis. Specific Embodiments The following further describes the present invention in conjunction with embodiments. The following embodiments are explanations of the present invention, and the present invention is not limited to the following embodiments: Example 1 A method for preparing a high γ-aminobutyric acid and selenium-rich mung bean product, the steps are as follows: S1. Soaking: Remove impurities from mung bean seeds, wash them, and disinfect them with 1.0% sodium hypochlorite solution. Soak the disinfected mung beans in a 10 mg / L nano-selenium solution for 6 h at a temperature of 20 °C to obtain soaked mung bean seeds; S2. Microwave treatment: Put the soaked mung bean seeds into a microwave device with a power of 200 W and perform microwave treatment for 30 s; S3. Hypoxic stress germination: Put the mung beans after microwave treatment into a vacuum drying incubator for hypoxic vacuum germination. The vacuum degree is 1.3 kPa, the temperature is 25 °C, and the time is 8 h; S4. Acid and salt stress germination: Transfer the mung beans after hypoxic vacuum germination to a constant temperature and humidity incubator to continue germination. The temperature is 25 °C, the concentration of succinic acid solution is 3 mg / mL, and the salt solution is 0.03 M ammonium acetate solution. Spray on the surface of the mung beans every 3 h during germination, alternating between the acid solution and the salt solution. After 8 h of germination, obtain high γ-aminobutyric acid-rich selenium-enriched mung bean sprouts; S5. Drying and dehydration: Dehydrate the high γ-aminobutyric acid-rich selenium-enriched mung bean sprouts by hot air drying at 45 °C for 6 h; S6. Baking: Bake the dried and dehydrated high γ-aminobutyric acid-rich selenium-enriched mung bean sprouts at a temperature of 130 °C for 20 min. During the baking process, turn them over once every 10 min; S7. Processing of mung bean products: Cool the baked high γ-aminobutyric acid-rich selenium-enriched mung bean sprouts to room temperature, crush the whole mung bean sprouts with a pulverizer for 150 s to 200 mesh, and then vacuum package to obtain mung bean sprout powder. Example 2 A preparation method of high γ-aminobutyric acid-rich selenium-enriched mung bean products is as follows: S1. Soaking: Remove impurities from mung bean seeds, wash them, and disinfect them with 1.0% sodium hypochlorite solution. Soak the disinfected mung beans in a 5 mg / L nano-selenium solution for 6 h at a temperature of 20 °C to obtain soaked mung bean seeds; S2. Microwave treatment: Put the soaked mung bean seeds into a microwave device with a power of 200 W and perform microwave treatment for 30 s; S3. Hypoxic stress germination: Put the mung beans after microwave treatment into a vacuum drying incubator for hypoxic vacuum germination. The vacuum degree is 1.3 kPa, the temperature is 25 °C, and the time is 8 h; S4. Acid and salt stress germination: Transfer the mung beans after hypoxic vacuum germination to a constant temperature and humidity incubator to continue germination. The temperature is 25 °C, the concentration of succinic acid solution is 3 mg / mL, and the salt solution is 0.03 M ammonium acetate solution. Spray on the surface of the mung beans every 3 h during germination, alternating between the acid solution and the salt solution. After 8 h of germination, obtain high γ-aminobutyric acid-rich selenium-enriched mung bean sprouts; S5. Drying and dehydration: Dehydrate the high γ-aminobutyric acid-rich selenium-enriched mung bean sprouts by hot air drying at 45 °C for 6 h; S6. Baking: The dried and dehydrated high-GABA selenium-enriched mung bean sprouts are baked at 130 °C for 20 min. During the baking process, turn them over every 10 min; S7. Processing of mung bean products: The baked high-GABA selenium-enriched mung bean sprouts are cooled to room temperature, and the whole mung bean sprouts are crushed into 200 mesh by a crusher for 150 s and then vacuum-packed to obtain mung bean sprout powder. Example 3 A preparation method of high-GABA selenium-enriched mung bean products is as follows: S1. Soaking: Remove impurities, wash the mung bean seeds, and disinfect them with 1.0% sodium hypochlorite solution. The disinfected mung beans are soaked in 10 mg / L nano-selenium solution for 6 h at 20 °C to obtain soaked mung bean seeds; S2. Microwave treatment: The soaked mung bean seeds are put into a microwave device with a power of 200 W and microwave-treated for 30 s; S3. Hypoxic stress germination: The microwave-treated mung beans are put into a vacuum drying incubator for hypoxic vacuum germination. The vacuum degree is 1.3 kPa, the temperature is 25 °C, and the time is 6 h; S4. Acid and salt stress germination: The mung beans after hypoxic vacuum germination are transferred to a constant temperature and humidity incubator to continue germinating. The temperature is 25 °C, the concentration of succinic acid solution is 3 mg / mL, and the salt solution is 0.03 M ammonium acetate solution. Spray them on the surface of the mung beans every 3 h during germination, alternating between the acid solution and the salt solution. After 8 h of germination, high-GABA selenium-enriched mung bean sprouts are obtained; S5. Drying and dehydration: The high-GABA selenium-enriched mung bean sprouts are dehydrated by hot air drying at 45 °C for 6 h; S6. Baking: The dried and dehydrated high-GABA selenium-enriched mung bean sprouts are baked at 130 °C for 20 min. During the baking process, turn them over every 10 min; S7. Processing of mung bean products: The baked high-GABA selenium-enriched mung bean sprouts are cooled to room temperature, and the whole mung bean sprouts are crushed into 200 mesh by a crusher for 150 s and then vacuum-packed to obtain mung bean sprout powder. Example 4 A preparation method of high-GABA selenium-enriched mung bean products is as follows: S1. Soaking: Remove impurities, wash the mung bean seeds, and disinfect them with 1.0% sodium hypochlorite solution. The disinfected mung beans are soaked in 10 mg / L nano-selenium solution for 6 h at 20 °C to obtain soaked mung bean seeds; S2. Microwave treatment: The soaked mung bean seeds are put into a microwave device with a power of 200 W and microwave-treated for 30 s; S3. Hypoxic stress germination: The mung beans after microwave treatment are placed in a vacuum drying incubator for hypoxic vacuum germination. The vacuum degree is 1.3 kPa, the temperature is 25 °C, and the time is 8 h; S4. Acid and salt stress germination: The mung beans after hypoxic vacuum germination are transferred to a constant temperature and humidity incubator to continue germinating. The temperature is 25 °C, the concentration of the succinic acid solution is 3 mg / mL, and the salt solution is 0.03 M ammonium acetate solution. During germination, it is sprayed on the surface of the mung beans every 3 h, alternating between the acid solution and the salt solution. After 10 h of germination, high γ-aminobutyric acid-enriched selenium mung bean sprouts are obtained; S5. Drying and dehydration: The high γ-aminobutyric acid-enriched selenium mung bean sprouts are dehydrated by hot air drying at 45 °C for 6 h; S6. Baking: The dried and dehydrated high γ-aminobutyric acid-enriched selenium mung bean sprouts are baked at 130 °C for 20 min. During the baking process, they are turned over every 10 min; S7. Processing of mung bean products: The baked high γ-aminobutyric acid-enriched selenium mung bean sprouts are cooled to room temperature, and the whole mung bean sprouts are ground into 200-mesh powder by a grinder for 150 s and then vacuum-packed to obtain mung bean sprout powder. Example 5 A preparation method of a high γ-aminobutyric acid-enriched selenium mung bean product is as follows: S1. Soaking: The mung bean seeds are decontaminated, washed, and disinfected with 1.0% sodium hypochlorite solution. The disinfected mung beans are soaked in a 10 mg / L nano-selenium solution for 6 h at a temperature of 20 °C to obtain soaked mung bean seeds; S2. Microwave treatment: The soaked mung bean seeds are put into a microwave device with a power of 200 W and treated with microwave for 30 s; S3. Hypoxic stress germination: The mung beans after microwave treatment are placed in a vacuum drying incubator for hypoxic vacuum germination. The vacuum degree is 1.3 kPa, the temperature is 25 °C, and the time is 8 h; S4. Acid and salt stress germination: The mung beans after hypoxic vacuum germination are transferred to a constant temperature and humidity incubator to continue germinating. The temperature is 25 °C, the concentration of the succinic acid solution is 5 mg / mL, and the salt solution is 0.03 M ammonium acetate solution. During germination, it is sprayed on the surface of the mung beans every 3 h, alternating between the acid solution and the salt solution. After 8 h of germination, high γ-aminobutyric acid-enriched selenium mung bean sprouts are obtained; S5. Drying and dehydration: The high γ-aminobutyric acid-enriched selenium mung bean sprouts are dehydrated by hot air drying at 45 °C for 6 h; S6. Baking: The dried and dehydrated high γ-aminobutyric acid-enriched selenium mung bean sprouts are baked at 130 °C for 20 min. During the baking process, they are turned over every 10 min; S7. Processing of mung bean products: The baked high γ-aminobutyric acid-enriched selenium mung bean sprouts are cooled to room temperature, and the whole mung bean sprouts are ground into 200-mesh powder by a grinder for 150 s and then vacuum-packed to obtain mung bean sprout powder. Example 6 A preparation method of a high γ-aminobutyric acid and selenium-rich mung bean product is as follows: S1. Soaking: Remove impurities from mung bean seeds, wash them, and disinfect them with 1.0% sodium hypochlorite solution. The disinfected mung beans are soaked in a 10 mg / L nano-selenium solution for 6 h at a temperature of 20 °C to obtain soaked mung bean seeds; S2. Microwave treatment: The soaked mung bean seeds are put into a microwave device with a power of 200 W and treated with microwave for 30 s; S3. Hypoxic stress germination: The mung beans after microwave treatment are put into a vacuum drying incubator for hypoxic vacuum germination. The vacuum degree is 1.3 kPa, the temperature is 25 °C, and the time is 8 h; S4. Acid and salt stress germination: The mung beans after hypoxic vacuum germination are transferred to a constant temperature and humidity incubator to continue germinating. The temperature is 25 °C, the concentration of succinic acid solution is 3 mg / mL, and the salt solution is 0.03 M ammonium acetate solution. During germination, it is sprayed on the surface of mung beans every 3 h, alternating between acid solution and salt solution. After 8 h of germination, high γ-aminobutyric acid and selenium-rich germinated mung beans are obtained; S5. Drying and dehydration: The high γ-aminobutyric acid and selenium-rich germinated mung beans are dehydrated by hot air drying at 45 °C for 6 h; S6. Baking: The high γ-aminobutyric acid and selenium-rich germinated mung beans after drying and dehydration are baked at a temperature of 130 °C for 20 min. During baking, they are turned over every 10 min; S7. Processing of mung bean products: The high γ-aminobutyric acid and selenium-rich germinated mung beans after baking are cooled to room temperature and then vacuum-packed to make bagged germinated mung bean tea. Example 7 A preparation method of a high γ-aminobutyric acid and selenium-rich mung bean product is as follows: S1. Soaking: Remove impurities from mung bean seeds, wash them, and disinfect them with 1.0% sodium hypochlorite solution. The disinfected mung beans are soaked in a 10 mg / L nano-selenium solution for 6 h at a temperature of 20 °C to obtain soaked mung bean seeds; S2. Microwave treatment: The soaked mung bean seeds are put into a microwave device with a power of 200 W and treated with microwave for 30 s; S3. Hypoxic stress germination: The mung beans after microwave treatment are put into a vacuum drying incubator for hypoxic vacuum germination. The vacuum degree is 1.3 kPa, the temperature is 25 °C, and the time is 8 h; S4. Acid and salt stress germination: The mung beans after hypoxic vacuum germination are transferred to a constant temperature and humidity incubator to continue germinating. The temperature is 25 °C, the concentration of succinic acid solution is 3 mg / mL, and the salt solution is 0.03 M ammonium acetate solution. During germination, it is sprayed on the surface of mung beans every 3 h, alternating between acid solution and salt solution. After 8 h of germination, high γ-aminobutyric acid and selenium-rich germinated mung beans are obtained; S5. Drying and dehydration: The high γ-aminobutyric acid-rich selenium-enriched mung bean sprouts are dehydrated by hot air drying at 45°C for 6 hours; S6. Baking: The dried and dehydrated high γ-aminobutyric acid-rich selenium-enriched mung bean sprouts are baked at 130°C for 20 minutes. During the baking process, they are turned over once every 10 minutes; S7. Processing of mung bean products: The baked high γ-aminobutyric acid-rich selenium-enriched mung bean sprouts are cooled to room temperature, and the whole mung bean sprouts are crushed with a crusher for 10 seconds to 12 mesh and then vacuum-packed to obtain mung bean sprout tea powder. Comparative Example 1 The difference between this comparative example and Example 1 is that distilled water is used instead of the nano-selenium solution, as follows: S1. Soaking: The mung bean seeds are decontaminated, washed, and disinfected with 1.0% sodium hypochlorite solution. The disinfected mung beans are soaked in distilled water for 6 hours at a temperature of 20°C to obtain soaked mung bean seeds; S2. Microwave treatment: The soaked mung bean seeds are put into a microwave device with a power of 200 W and microwave-treated for 30 s; S3. Hypoxia stress germination: The microwave-treated mung beans are put into a vacuum drying incubator for hypoxic vacuum germination. The vacuum degree is 1.3 kPa, the temperature is 25°C, and the time is 8 hours; S4. Acid and salt stress germination: The mung beans after hypoxic vacuum germination are transferred to a constant temperature and humidity incubator to continue germinating. The temperature is 25°C, the concentration of succinic acid solution is 3 mg / mL, and the salt solution is 0.03 M ammonium acetate solution. During germination, it is sprayed on the surface of the mung beans once every 3 hours, alternating between the acid solution and the salt solution. After 8 hours of germination, high γ-aminobutyric acid-rich selenium-enriched mung bean sprouts are obtained; S5. Drying and dehydration: The high γ-aminobutyric acid-rich selenium-enriched mung bean sprouts are dehydrated by hot air drying at 45°C for 6 hours; S6. Baking: The dried and dehydrated high γ-aminobutyric acid-rich selenium-enriched mung bean sprouts are baked at 130°C for 20 minutes. During the baking process, they are turned over once every 10 minutes; S7. Processing of mung bean products: The baked high γ-aminobutyric acid-rich selenium-enriched mung bean sprouts are cooled to room temperature, and the whole mung bean sprouts are crushed with a crusher for 150 seconds to 200 mesh and then vacuum-packed to obtain mung bean sprout powder. Comparative Example 2 The difference between this comparative example and Example 1 is that hypoxia stress germination is not adopted, as follows: S1. Soaking: The mung bean seeds are decontaminated, washed, and disinfected with 1.0% sodium hypochlorite solution. The disinfected mung beans are soaked in 10 mg / L nano-selenium solution for 6 hours at a temperature of 20°C to obtain soaked mung bean seeds; S2. Microwave treatment: The soaked mung bean seeds are put into a microwave device with a power of 200 W and microwave-treated for 30 s; S3. Acid and salt stress germination: The mung beans after hypoxia-vacuum germination are transferred to a constant temperature and humidity incubator for continued germination at a temperature of 25°C. The concentration of the succinic acid solution is 3 mg / mL, and the salt solution is 0.03 M ammonium acetate solution. During germination, it is sprayed on the surface of the mung beans every 3 h, alternating between the acid solution and the salt solution. After 16 h of germination, high γ-aminobutyric acid-enriched selenium-enriched mung bean sprouts are obtained; S4. Drying and dehydration: The high γ-aminobutyric acid-enriched selenium-enriched mung bean sprouts are dehydrated by hot air drying at 45°C for 6 h; S5. Baking: The dried and dehydrated high γ-aminobutyric acid-enriched selenium-enriched mung bean sprouts are baked at a temperature of 130°C for 20 min. During the baking process, they are turned over every 10 min; S6. Processing of mung bean products: The baked high γ-aminobutyric acid-enriched selenium-enriched mung bean sprouts are cooled to room temperature, and the whole mung bean sprouts are ground into 200-mesh powder by a pulverizer for 150 s and then vacuum-packed to obtain mung bean sprout powder. Comparative Example 3 The difference between this comparative example and Example 1 is that acid stress germination is not adopted, and the specific steps are as follows: S1. Soaking: The mung bean seeds are decontaminated, washed, and disinfected with 1.0% sodium hypochlorite solution. The disinfected mung beans are soaked in a 10 mg / L nano-selenium solution for 6 h at a temperature of 20°C to obtain soaked mung bean seeds; S2. Microwave treatment: The soaked mung bean seeds are put into a microwave device with a power of 200 W and microwave-treated for 30 s; S3. Hypoxia stress germination: The microwave-treated mung beans are put into a vacuum drying incubator for hypoxia-vacuum germination with a vacuum degree of 1.3 kPa, a temperature of 25°C, and a time of 8 h; S4. Salt stress germination: The mung beans after hypoxia-vacuum germination are transferred to a constant temperature and humidity incubator for continued germination at a temperature of 25°C. The salt solution is 0.03 M ammonium acetate solution. During germination, it is sprayed on the surface of the mung beans every 3 h. After 8 h of germination, high γ-aminobutyric acid-enriched selenium-enriched mung bean sprouts are obtained; S5. Drying and dehydration: The high γ-aminobutyric acid-enriched selenium-enriched mung bean sprouts are dehydrated by hot air drying at 45°C for 6 h; S6. Baking: The dried and dehydrated high γ-aminobutyric acid-enriched selenium-enriched mung bean sprouts are baked at a temperature of 130°C for 20 min. During the baking process, they are turned over every 10 min; S7. Processing of mung bean products: The baked high γ-aminobutyric acid-enriched selenium-enriched mung bean sprouts are cooled to room temperature, and the whole mung bean sprouts are ground into 200-mesh powder by a pulverizer for 150 s and then vacuum-packed to obtain mung bean sprout powder. Comparative Example 4 The difference between this comparative example and Example 1 is that salt stress germination is not adopted, and the specific steps are as follows: S1. Soaking: Remove impurities from mung bean seeds, wash them, and disinfect them with 1.0% sodium hypochlorite solution. The disinfected mung beans are soaked in a 10 mg / L nano-selenium solution for 6 h at a temperature of 20 °C to obtain soaked mung bean seeds; S2. Microwave treatment: The soaked mung bean seeds are put into a microwave device with a power of 200 W and treated with microwave for 30 s; S3. Hypoxia stress germination: The mung beans after microwave treatment are put into a vacuum drying incubator for hypoxia vacuum germination. The vacuum degree is 1.3 kPa, the temperature is 25 °C, and the time is 8 h; S4. Acid stress germination: The mung beans after hypoxia vacuum germination are transferred to a thermostatic and humid incubator to continue germinating. The temperature is 25 °C, the concentration of succinic acid solution is 3 mg / mL, and it is sprayed on the surface of mung beans every 3 h during germination. After 8 h of germination, high γ-aminobutyric acid-enriched selenium sprout beans are obtained; S5. Drying and dehydration: The high γ-aminobutyric acid-enriched selenium sprout beans are dehydrated by hot air drying at 45 °C for 6 h; S6. Baking: The high γ-aminobutyric acid-enriched selenium sprout beans after drying and dehydration are baked at a temperature of 130 °C for 20 min. During the baking process, they are turned over every 10 min; S7. Processing of mung bean products: The high γ-aminobutyric acid-enriched selenium sprout beans after baking are cooled to room temperature. The whole sprout beans are ground into 200-mesh powder by a grinder for 150 s and then vacuum-packed to obtain sprout bean powder. Comparative Example 5 The difference between this comparative example and Example 1 is that the salt solution used is sodium chloride solution, and the details are as follows: S1. Soaking: Remove impurities from mung bean seeds, wash them, and disinfect them with 1.0% sodium hypochlorite solution. The disinfected mung beans are soaked in a 10 mg / L nano-selenium solution for 6 h at a temperature of 20 °C to obtain soaked mung bean seeds; S2. Microwave treatment: The soaked mung bean seeds are put into a microwave device with a power of 200 W and treated with microwave for 30 s; S3. Hypoxia stress germination: The mung beans after microwave treatment are put into a vacuum drying incubator for hypoxia vacuum germination. The vacuum degree is 1.3 kPa, the temperature is 25 °C, and the time is 8 h; S4. Acid and salt stress germination: The mung beans after hypoxia vacuum germination are transferred to a thermostatic and humid incubator to continue germinating. The temperature is 25 °C, the concentration of succinic acid solution is 3 mg / mL, the salt solution is 0.03 M sodium chloride solution, and it is sprayed on the surface of mung beans every 3 h during germination, alternating between acid solution and salt solution. After 8 h of germination, high γ-aminobutyric acid-enriched selenium sprout beans are obtained; S5. Drying and dehydration: The high γ-aminobutyric acid-enriched selenium sprout beans are dehydrated by hot air drying at 45 °C for 6 h; S6. Baking: The dried and dehydrated high-GABA selenium-enriched mung bean sprouts are baked at 130 °C for 20 min. During the baking process, turn them over once every 10 min; S7. Processing of mung bean products: The baked high-GABA selenium-enriched mung bean sprouts are cooled to room temperature, and the whole mung bean sprouts are ground into 200-mesh powder with a grinder for 150 s and then vacuum-packed to obtain mung bean sprout powder. Comparative Example 6 The difference between this comparative example and Example 1 is that the acid solution used is citric acid solution, which is specifically as follows: S1. Soaking: Remove impurities, wash the mung bean seeds, and disinfect them with 1.0% sodium hypochlorite solution. The disinfected mung beans are soaked in 10 mg / L nano-selenium solution for 6 h at a temperature of 20 °C to obtain soaked mung bean seeds; S2. Microwave treatment: The soaked mung bean seeds are put into a microwave device with a power of 200 W and microwave-treated for 30 s; S3. Hypoxic stress germination: The microwave-treated mung beans are put into a vacuum drying incubator for hypoxic vacuum germination. The vacuum degree is 1.3 kPa, the temperature is 25 °C, and the time is 8 h; S4. Acid and salt stress germination: The mung beans after hypoxic vacuum germination are transferred to a constant temperature and humidity incubator to continue germinating. The temperature is 25 °C, the concentration of citric acid solution is 3 mg / mL, and the salt solution is 0.03 M ammonium acetate solution. Spray them on the surface of the mung beans once every 3 h during germination, alternating between acid solution and salt solution. After 8 h of germination, high-GABA selenium-enriched mung bean sprouts are obtained; S5. Drying and dehydration: The high-GABA selenium-enriched mung bean sprouts are dehydrated by hot air drying at 45 °C for 6 h; S6. Baking: The dried and dehydrated high-GABA selenium-enriched mung bean sprouts are baked at 130 °C for 20 min. During the baking process, turn them over once every 10 min; S7. Processing of mung bean products: The baked high-GABA selenium-enriched mung bean sprouts are cooled to room temperature, and the whole mung bean sprouts are ground into 200-mesh powder with a grinder for 150 s and then vacuum-packed to obtain mung bean sprout powder. Comparative Example 7 The difference between this comparative example and Example 1 is that only citric acid stress is used without adding salt solution, which is specifically as follows: S1. Soaking: Remove impurities, wash the mung bean seeds, and disinfect them with 1.0% sodium hypochlorite solution. The disinfected mung beans are soaked in 10 mg / L nano-selenium solution for 6 h at a temperature of 20 °C to obtain soaked mung bean seeds; S2. Microwave treatment: The soaked mung bean seeds are put into a microwave device with a power of 200 W and microwave-treated for 30 s; S3. Hypoxic stress germination: The mung beans after microwave treatment are placed in a vacuum drying incubator for hypoxic vacuum germination. The vacuum degree is 1.3 kPa, the temperature is 25 °C, and the time is 8 h; S4. Acid and salt stress germination: The mung beans after hypoxic vacuum germination are transferred to a thermostatic and humid incubator to continue germinating. The temperature is 25 °C, the concentration of the citric acid solution is 3 mg / mL, and it is sprayed on the surface of the mung beans every 3 h during germination. After 8 h of germination, high γ-aminobutyric acid-enriched selenium sprout beans are obtained; S5. Drying and dehydration: The high γ-aminobutyric acid-enriched selenium sprout beans are dehydrated by hot air drying at 45 °C for 6 h; S6. Baking: The dried and dehydrated high γ-aminobutyric acid-enriched selenium sprout beans are baked at 130 °C for 20 min. During the baking process, they are turned over every 10 min; S7. Processing of mung bean products: The baked high γ-aminobutyric acid-enriched selenium sprout beans are cooled to room temperature, and the whole sprout beans are ground into 200-mesh powder by a pulverizer for 150 s and then vacuum-packed to obtain sprout bean powder. Comparative Example 8 The difference between this comparative example and Example 3 is that only sodium chloride solution stress is applied without adding acid solution, as follows: S1. Soaking: The mung bean seeds are decontaminated, washed, and disinfected with 1.0% sodium hypochlorite solution. The disinfected mung beans are soaked in 10 mg / L nano-selenium solution for 6 h at a temperature of 20 °C to obtain soaked mung bean seeds; S2. Microwave treatment: The soaked mung bean seeds are put into a microwave device with a power of 200 W and microwave-treated for 30 s; S3. Hypoxic stress germination: The mung beans after microwave treatment are placed in a vacuum drying incubator for hypoxic vacuum germination. The vacuum degree is 1.3 kPa, the temperature is 25 °C, and the time is 8 h; S4. Acid and salt stress germination: The mung beans after hypoxic vacuum germination are transferred to a thermostatic and humid incubator to continue germinating. The temperature is 25 °C, and the salt solution is 0.03 M sodium chloride solution. It is sprayed on the surface of the mung beans every 3 h during germination. After 8 h of germination, high γ-aminobutyric acid-enriched selenium sprout beans are obtained; S5. Drying and dehydration: The high γ-aminobutyric acid-enriched selenium sprout beans are dehydrated by hot air drying at 45 °C for 6 h; S6. Baking: The dried and dehydrated high γ-aminobutyric acid-enriched selenium sprout beans are baked at 130 °C for 20 min. During the baking process, they are turned over every 10 min; S7. Processing of mung bean products: The baked high γ-aminobutyric acid-enriched selenium sprout beans are cooled to room temperature, and the whole sprout beans are ground into 200-mesh powder by a pulverizer for 150 s and then vacuum-packed to obtain sprout bean powder. Performance measurement: 1. Determination of GABA content: Analysis was performed using ultra-high performance liquid chromatography tandem quadrupole mass spectrometry (UPLC-QQQ-MS). The chromatographic column was C18 (100 mm × 3 mm), the column temperature was 30 °C, and the injection volume was 10 μL. Binary gradient mobile phase: water containing 0.1% formic acid (A) and acetonitrile (B), the flow rate was set at 0.2 mL / min, and the injection volume was 10 μL. Gradient elution program: 0 - 3 min, 95 - 5% B;; 3 - 4 min, 10 - 90% B; 4 - 6 min, 10 - 90% B; 6 - 8 min, 95 - 5% B. Mass spectrometry conditions: electrospray ionization source (ESI), positive ion (ESI + ) mode, scanning mode MRM, capillary voltage 0.35 KV, cone voltage 30 V, ion source temperature 150 °C, desolvation gas temperature 500 °C, the flow rates of cone gas (He) and desolvation gas (N2) were 20 L / h and 800 L / h respectively. The quantitative ion pair of GABA was 104.0 / 87.0 (m / z). The GABA content was calculated by the external standard peak area. 2. Determination of organic selenium content: The fluorescence spectrophotometry was used to determine the total selenium and inorganic selenium contents respectively, and the organic selenium content was the difference between the total selenium content and the inorganic selenium content. The method for determining the total selenium was as follows: Weigh 0.5 g of the sample and put it into a conical flask, add 10 mL of nitric acid-perchloric acid mixture (9:1) and digest overnight. Heat it the next day, and add nitric acid appropriately until the solution is clear, colorless and emits white smoke. Continue to heat until about 2 mL remains, cool it, add 5 mL of 6M HCl, and heat it again until it is clear and emits white smoke, and about 2 mL remains. Then add HCl solution (1+9) to 5 mL, add 20 mL of EDTA mixture, and adjust it to light red-orange (pH 1.5 - 2.0) with ammonia water solution (1:1) and hydrochloric acid solution (1:9). Add 3 mL of DAN reagent (1 g / L) under dark conditions, mix well, heat it in a boiling water bath for 5 min, cool it, and extract with cyclohexane to measure the fluorescence intensity. Calculate the total selenium content according to the national standard method. Determination of the inorganic selenium content: Weigh 0.2 g of corn sample into a centrifuge tube, add 20 mL of ultrapure water and mix well. Put the centrifuge tube into an ultrasonic instrument and extract for 20 min, then centrifuge to obtain the inorganic selenium extract, and then measure the inorganic selenium content according to the steps for determining the total selenium content. 3. Determination of total flavonoid and total phenol contents: The total phenol content was determined by the Folin-Ciocalteu colorimetric method. Add 10% Folin-Ciocalteu reagent (40 μL) to 20 μL of the polyphenol extract, react fully for 5 min, and then add 160 μL of sodium carbonate solution with a concentration of 75 g / L (w / v). Subsequently, measure the absorbance at 750 nm after reacting in the dark at 25 °C for 90 min. Using ferulic acid as the standard, the total phenol content was expressed as milligrams of ferulic acid equivalent per 100 grams (mg FAE / 100g). The total flavonoid content was determined by the AlCl3 colorimetric method. 75 μL of 5% NaNO2 solution and 150 μL of 10% AlCl3 solution were added to the sample extract respectively. After the mixture reacted at room temperature for 1 min, 0.5 mL of 4% NaOH solution was added, and distilled water was added to make the total volume reach 2.5 mL. After reacting in the dark for 15 min, the absorbance was measured at 510 nm. Using rutin as the standard, the total flavonoid content was measured in milligrams of rutin equivalent per kilogram of sample (mg RE / kg). Table 1 Contents of various nutrients in the germinated soybean powder prepared in Examples 1-7 and Comparative Examples 1-8 IE represents isovitexin equivalent, and FAE represents ferulic acid equivalent As can be seen from Table 1, the GABA content in Examples 1-7 was between 330.80±1.24 mg / kg and 333.78±1.34 mg / kg, with little fluctuation, the GABA content was relatively high and consistent. The organic selenium content was between 7.00±0.24 mg / kg and 7.95±0.18 mg / kg, much higher than the selenium-rich food standard (selenium content ≥ 0.15 mg / kg), and it could be used as a dietary selenium supplement ingredient to increase the daily selenium intake of the human body. The same was true for the relatively high and stable contents of total flavonoids and total phenols, indicating that within a certain range of process parameter adjustments, the impact on the nutrient content of the product was not significant, and the content of each substance in Example 1 was the highest; the contents of various nutrients in Comparative Examples 1-8 fluctuated greatly, especially in Comparative Examples 1, 7, and 8, and the contents of GABA, organic selenium, total flavonoids, and total phenols were significantly lower than those in the examples, indicating that the preparation processes of these comparative examples could not effectively retain or generate these nutrients. The organic selenium content of Comparative Example 1 without selenium enrichment treatment was extremely low, and the GABA content was also low, indicating that soaking in selenium-rich solution could significantly increase the selenium content in germinated soybean powder and also affect the GABA content. The selenium enrichment process also had a certain effect on the biosynthesis of antioxidant polyphenols and flavonoids in mung beans; the GABA content in Comparative Examples 7 and 8 was lower than that in Comparative Examples 3 and 4, indicating that the effect of stress enrichment of GABA with succinic acid and ammonium acetate was better than that with citric acid and sodium chloride, and the GABA content in Comparative Examples 3 and 4 was lower than that in the examples, indicating that the combined stress of acid and salt was better than the stress of using acid or salt alone in promoting GABA accumulation. Comparing Comparative Examples 5 and 6 with the examples also showed that the combined effect of these two acid salts was better. Compared with the examples, the content of each substance in Comparative Example 2 decreased, indicating that low-oxygen culture was also very important for the enrichment of nutrients, especially having the greatest impact on phenolic substances. 4. Determination of vitexin and isovitexin: Determined by high performance liquid chromatography. The high performance liquid chromatograph (HPLC) is equipped with a diode array detector (DAD); chromatographic column: C18 column (4.6×150 mm), column temperature: 35 °C; mobile phase (A) acetonitrile, mobile phase (B) 0.2% acetic acid aqueous solution; flow rate: 1 mL / min; gradient elution program: 0 - 30 min, 95 - 65% B; 30 - 31 min, 65 - 95% B; 31 - 40 min, 95% B; injection volume: 2 μL; detection wavelength: 336 nm. The external standard method is used to calculate the contents of vitexin and isovitexin respectively through the peak areas at 336 nm, calculated in mg / kg. 5. Determination of total selenium: Weigh 0.5 g of the sample and put it into a conical flask, add 10 mL of a nitric acid - perchloric acid mixture (9:1) and digest overnight. Heat it the next day, and add nitric acid appropriately until the solution is clear, colorless and emits white smoke, continue heating until about 2 mL remains, cool it and then add 5 mL of 6M hydrochloric acid solution, heat it again until it is clear and emits white smoke, and about 2 mL remains. Subsequently, add hydrochloric acid solution (1:9) to make it 5 mL, add 20 mL of EDTA mixture, and adjust it to light red - orange (pH 1.5 - 2.0) with ammonia water (1:1) and hydrochloric acid (1:9). Add 3 mL of DAN reagent (1 g / L) under light - proof conditions, mix well and place it in a boiling water bath for 5 min, cool it and then extract with cyclohexane, and measure the fluorescence intensity. Calculate the total selenium content according to the national standard method. Table 2 Contents of various nutrients in the germinated bean powder prepared in Example 1 and Comparative Examples 1 - 8 As can be seen from Table 2, the contents of vitexin and isovitexin in Example 1 are significantly higher than those in the comparative examples. After selenium - enrichment treatment, there is no significant difference in the total selenium content, but the organic selenium conversion rate in Example 1 is relatively high; the selenium - enrichment treatment has a more significant impact on the contents of vitexin and isovitexin, followed by Comparative Examples 7 and 8, which indicates that the effect of germinating and enriching nutrients under citric acid and sodium chloride stress is lower than that under succinic acid and ammonium acetate stress. Comparative Examples 3 and 4 are lower than Example 1 and Comparative Examples 5 and 6, indicating that the combined stress of acid and salt is significant for enriching vitexin and isovitexin. 6. Sensory evaluation Ten people trained in sensory evaluation were used for sensory evaluation. The scoring standard was to score the samples using a 9 - point happy scale (9 = especially like; 8 = very like; 7 = like; 6 = a little like; 5 = neutral; 4 = a little dislike; 3 = moderately dislike; 2 = dislike; 1 = very dislike). The germinated bean powder prepared in Example 1 and Comparative Examples 1 - 8 was subjected to sensory evaluation, and the results are as follows: Table 3 Sensory evaluation results of the germinated bean powder prepared in Example 1 and Comparative Examples 1 - 8 As can be seen from Table 3, the mung bean sprouts powder soaked in the selenium-rich solution has a high degree of preference in terms of color, fragrance and acceptability, which proves that the high-GABA selenium-rich mung bean products have good flavor, high development value and market prospects. The color of Comparative Example 1 without selenium-rich treatment is the worst, but its taste is better; followed by Comparative Example 2 without low-oxygen cultivation, which has a poor color, but has a strong fragrance; the fragrance of citric acid (Comparative Example 7) is significantly affected compared with succinic acid (Comparative Example 4). Comparative Example 8 only added sodium chloride and is more acceptable in terms of sensory properties; adding only acid or salt will affect the taste of mung bean sprouts powder. The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a high-γ-aminobutyric acid selenium-enriched mung bean product, characterized in that: The following steps are involved: S1. Soaking: The mung bean seeds were cleaned, washed, and disinfected with a 1.0% sodium hypochlorite solution, and the disinfected mung bean seeds were soaked in a selenium-rich solution to obtain soaked mung bean seeds; S2. Microwave treatment: placing the soaked mung bean seeds into a microwave device for microwave treatment; S3. Hypoxia stress germination: The mung bean seeds treated with microwaves were placed in a vacuum drying incubator for hypoxia vacuum germination; S4. Acid and salt stress germination: After low oxygen vacuum germination, the mung bean seeds were transferred to a constant temperature and humidity incubator for further germination. During the germination period, succinic acid solution and salt solution were sprayed on the surface of the mung beans. After the germination, high γ-aminobutyric acid and selenium-rich sprouts were obtained. S5. Drying and dehydration: drying and dehydrating the high γ-aminobutyric acid-rich selenium sprouts by hot air drying at 40-50° C. for 3-12 hours; S6. Baking: Baking the dried and dehydrated high-γ-aminobutyric acid selenium-enriched bean sprouts; S7. Preparation of high-γ-aminobutyric acid and selenium-enriched mung bean products: The roasted high-γ-aminobutyric acid and selenium-enriched mung bean sprouts are cooled to room temperature and then processed and packaged.

2. The method for preparing a high-γ-aminobutyric acid selenium-enriched mung bean product according to claim 1, characterized in that: The selenium-rich solution in step S1 is a sodium selenite solution, an amino acid chelated selenium solution or a nano-selenium solution with a concentration of 5 to 25 mg / L.

3. The method for preparing a high-γ-aminobutyric acid selenium-enriched mung bean product according to claim 1, characterized in that: In step S1, the soaking temperature is 15-35° C., the soaking time is 2-12 hours, and the soaked mung beans are rinsed with drinking water 2-3 times.

4. The method for preparing a high-γ-aminobutyric acid selenium-enriched mung bean product according to claim 1, characterized in that: The microwave treatment conditions in step S2 are: power of 100-300 W, and time of 10-40 s.

5. The method for preparing a high-γ-aminobutyric acid selenium-enriched mung bean product according to claim 1, characterized in that: The conditions for low oxygen vacuum germination in step S3 are: vacuum degree of 1.1-1.5 kPa, temperature of 25-30° C., and time of 5-15 h.

6. The method for preparing a high-γ-aminobutyric acid selenium-enriched mung bean product according to claim 1, characterized in that: The temperature of the constant temperature and humidity incubator in step S4 is 25-30° C., and the germination time is 3-12 hours.

7. The method for preparing a high-γ-aminobutyric acid selenium-enriched mung bean product according to claim 1, characterized in that: In step S4, the concentration of the succinic acid solution is 2-5 mg / mL, and the salt solution is 0.01-0.05 M ammonium acetate solution. The specific spraying conditions are: spraying once every 3 hours, alternating between the succinic acid solution first and the salt solution.

8. The method for preparing a high-γ-aminobutyric acid selenium-enriched mung bean product according to claim 1, characterized in that: The baking conditions in step S6 are: a temperature of 110-150° C., a time of 10-50 min, and turning the dough 1-2 times every 10 min.

9. A high-γ-aminobutyric acid selenium-enriched mung bean product prepared by the preparation method according to any one of claims 1 to 8.

10. The high-γ-aminobutyric acid selenium-enriched mung bean product according to claim 9, characterized in that: The high-γ-aminobutyric acid and selenium-enriched mung bean products include sprout bean tea, sprout bean tea powder and sprout bean powder.

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