Preboiled rice rich in gamma-aminobutyric acid and preparation method thereof

Abstract

The invention provides preboiled rice rich in gamma-aminobutyric acid, and relates to the field of food processing. Comprising the following steps: S1, pretreatment: sequentially carrying out impurity removal, disinfection and cleaning treatment on rice; s2, magnetic field induction: at the temperature of 25-35 DEG C, the rice is treated for 30-120 min in a pulsed magnetic field of 10-20 mT; s3, soaking: soaking the rice subjected to magnetic field treatment in a soaking solution at 5-15 DEG C for 2-6 hours; soaking in a soaking solution at 55-60 DEG C for 1-2 hours; s4, performing ultrasonic-assisted germination: putting the soaked rice in an ultrasonic environment with the frequency of 35-45kHz and the power density of 0.3-0.8 W / cm < 2 >, and performing ultrasonic-induced germination at 28-32 DEG C for 24-48 hours; when buds grow to 1-3 mm, germination is stopped, and vacuum freeze drying is carried out; s5, steaming: steaming the unhulled rice treated in the step S4 at 110-120 DEG C for 5-15 minutes, and then air-drying the unhulled rice; and S6, hulling: hulling and milling the unhulled rice treated in the step S5 to obtain the preboiled rice. Through magnetic field pretreatment, low-temperature induction and ultrasonic-assisted germination, the germination rate of the rice is increased, and generation and enrichment of gamma-aminobutyric acid are promoted.

Description

Technical Field

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

[0002] Rice is one of the staple foods in southern my country. It is a typical seed of the grass family. It is rich in nutrients, and different parts have different functions and nutrients:

[0003] Rice husk: Rice husk is the outermost protective structure of rice, accounting for about 18%-20% of the weight of rice. It is hard and mainly composed of cellulose, lignin and silica. The function of rice husk is to protect the embryo and endosperm inside the rice from external physical, chemical and biological factors, such as preventing erosion by insects and microorganisms, and resisting mechanical damage during harvesting, transportation and storage.

[0004] Pericarp and seed coat: The pericarp is located inside the husk and develops from the ovary wall; the seed coat develops from the integuments and wraps the rice seed. These two layers are closely connected, generally thin, and contain some pigments, proteins, fats and other ingredients. They play a certain protective role and affect the appearance quality of the rice, such as its color, to a certain extent.

[0005] Aleurone layer: The aleurone layer is located between the seed coat and the endosperm. It is a tissue composed of one or several layers of cells. It is rich in nutrients such as protein, fat, minerals and vitamins, and has high nutritional value. When rice is processed into rice, the rice husk, pericarp, seed coat and aleurone layer will be removed after rice husking and milling.

[0006] Endosperm: Endosperm is the most important part of rice, accounting for about 70% to 80% of the weight of rice. It is a place to store nutrients, mainly starch, and also contains a small amount of protein and fat. The rice we eat daily is mainly composed of endosperm. The nutrients in the endosperm provide the nutrients needed for the development of the embryo during the germination of rice.

[0007] Embryo: The embryo is located on one side of the rice grain. Although it only accounts for 2% to 3% of the weight of the rice grain, it is the core part of the rice grain's life activities. The embryo includes structures such as the embryo, embryonic axis and radicle, and is rich in protein, fat, vitamins and enzymes. In the germination process of rice grains, the enzymes in the embryo play a key role in decomposing the nutrients in the endosperm and providing energy and material basis for the growth of the seedlings.

[0008] During the germination process of rice, a series of biochemical changes will occur inside it, and the starch inside will begin to convert into sugars, such as glucose. This conversion may make the germinated rice softer and sweeter than ungerminated rice. The protein in the endosperm is broken down into amino acids and soluble proteins by enzymes. These substances provide more nitrogen sources and nutritional support for the development of the embryo. During the germination process of rice, the activity of various enzymes will increase, such as amylase and protease. These enzymes play a key role in the germination process of rice, and can catalyze various biochemical reactions and promote the growth and development of rice. The vitamin content of rice will also change during the germination process. Some water-soluble vitamins such as B vitamins may increase, while some fat-soluble vitamins such as vitamin E may decrease due to oxidation.

[0009] GABA is an amino acid produced during rice germination. As an inhibitory neurotransmitter, it can improve brain function, nerve function, long-term memory, etc. In the prior art, brown rice is usually used as a raw material to promote the production of GABA through germination, but the content of GABA in the resulting rice products is still limited and cannot meet market demand. Summary of the invention

[0010] The invention aims to provide a method for preparing parboiled rice rich in gamma-aminobutyric acid, which improves the germination rate of rice and promotes the production and enrichment of gamma-aminobutyric acid through magnetic field pretreatment, low-temperature induction and ultrasound-assisted germination.

[0011] Another object of the present invention is to provide a parboiled rice rich in γ-aminobutyric acid, wherein the γ-aminobutyric acid content is ≥50 mg / 100 g, the sprout length is ≤3 mm, and the nutrition components are rich.

[0012] The present invention solves the technical problem by adopting the following technical solutions.

[0013] On the one hand, an embodiment of the present invention provides a method for preparing parboiled rice rich in γ-aminobutyric acid, comprising the following steps:

[0014] S1. Pretreatment: removing impurities, disinfecting and cleaning the rice in sequence;

[0015] S2. Magnetic field induction: The rice was treated in a pulsed magnetic field of 10-20 mT for 30-120 min at 25-35°C;

[0016] S3. Soaking: Soak the rice after magnetic field treatment in a soaking solution at 5-15°C for 2-6 hours; and then soak in a soaking solution at 55-60°C for 1-2 hours;

[0017] S4. Ultrasonic assisted germination: The soaked rice is placed in an ultrasonic assisted germination chamber at a frequency of 35-45kHz and a power density of 0.3-0.8W / cm 2 In an ultrasonic environment, ultrasonically induce germination at 28-32°C for 24-48 hours; when the buds reach 1-3 mm in length, terminate germination and vacuum freeze-dry;

[0018] S5. Steaming: Steam the rice after treatment in step S4 for 5 to 15 minutes at 110-120°C, and then air-dry;

[0019] S6. Hulling: Hulling and milling the rice after the treatment in step S5 to obtain parboiled rice.

[0020] In some embodiments of the present invention, the soaking solution comprises the following raw materials by mass fraction: 0.01-0.1wt% of glutamate decarboxylase, 0.05-0.2wt% of calcium lactate or calcium gluconate, 0.1-0.5wt% of calcium chloride, 0.05-0.2wt% of vitamin B6, and the balance is water.

[0021] In some embodiments of the present invention, in step S4, the moisture content of the rice after vacuum freeze drying is ≤12%.

[0022] In some embodiments of the present invention, in step S4, the ultrasonic induced germination process also includes dynamic gas regulation: a mixed gas containing CO2, O2 and inert gas is introduced into the rice, wherein the volume fraction of CO2 is 5-10%, the volume fraction of O2 is 10-15%, and the balance is inert gas.

[0023] In some embodiments of the present invention, the volume fraction of CO2 is maintained at 8-10% 24 hours before rice germination, and the volume fraction of CO2 is reduced to 5-7% within 24 hours after the germination. By controlling the CO2 content in the environment, excessive respiratory consumption is suppressed, and the GABA accumulation rate is increased by more than 2 times.

[0024] In some embodiments of the present invention, in the step S4, the ultrasonic induced germination process also includes spraying the rice with an aqueous solution of 0.5-5mmol / L γ-aminobutyric acid, 0.1-1mmol / L trehalose and 0.5-2mmol / L proline every 1-3 hours, and the spray flow rate is 50-300mL / min. By spraying the γ-aminobutyric acid aqueous solution exogenously, the content of γ-aminobutyric acid in the rice is increased, and trehalose and proline are added to the spray liquid to form a molecular protective layer, which cooperates with each other to prevent GABA from degrading during the spraying process, improve the γ-aminobutyric acid enrichment efficiency, and the γ-aminobutyric acid absorption rate after spraying is increased to 85%.

[0025] In some embodiments of the present invention, the pulsed magnetic field in step S2 is an alternating magnetic field with a frequency of 1-5 Hz, and the direction of the magnetic field is at an angle of 30-60° with the plane of the rice layer. The alternating magnetic field (10-20 mT) creates micropores in the cell membrane, promoting Ca 2+ Influx activates calmodulin signaling pathway and improves glutamate decarboxylase transcription efficiency; combined with low temperature (5-15°C), it induces glutamate decarboxylase expression through cold shock effect, while inhibiting GABA (γ-aminobutyric acid) transaminase (GABA-T) activity and reducing GABA decomposition; the combination of the two increases γ-aminobutyric acid synthetase activity by more than 40%, thereby enriching more γ-aminobutyric acid.

[0026] In some embodiments of the present invention, the ultrasonic treatment in step S4 is performed in an intermittent mode, with a working cycle of 5-10 minutes of ultrasonic treatment and 2-5 minutes of rest. Intermittent ultrasonic treatment (35-45kHz) enhances mass transfer, and CO2 (5-10%) inhibits the mitochondrial respiratory chain and reduces glutamate consumption.

[0027] In some embodiments of the present invention, the vacuum freeze drying in step S4 includes two stages: the first stage is pre-freezing at -30°C to -40°C for 2-4 hours, and the second stage is drying at a vacuum degree of 10-30Pa and a temperature of -50°C to -60°C for 12-24 hours. Through two-stage freeze drying, pre-freezing at -40°C can retain the cell structure, and vacuum sublimation can avoid degradation of heat-sensitive components in rice.

[0028] On the other hand, an embodiment of the present invention provides parboiled rice rich in γ-aminobutyric acid, which is prepared by the above method.

[0029] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0030] The preparation method of parboiled rice rich in γ-aminobutyric acid provided by the present invention combines pulsed magnetic field, low temperature soaking and ultrasonic treatment to promote rice germination, improve germination efficiency, promote the production of γ-aminobutyric acid in rice, and then increase the content of γ-aminobutyric acid. Among them, the pulsed magnetic field (10-20mT) causes micropores in the cell membrane, and the low temperature (5-15°C) induces the expression of GAD enzyme. The combination of the two increases the activity of GABA synthase by more than 40%; ultrasonic (35-45kHz) treatment can promote the diffusion of metabolites. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0032] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to specific embodiments.

[0033] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0034] Example 1

[0035] The parboiled rice of this example was prepared as follows.

[0036] S1. Pretreatment: removing impurities, disinfecting and cleaning the rice in sequence;

[0037] S2. Magnetic field induction: The rice was treated in an alternating pulse magnetic field of 10 mT and 5 Hz for 100 min at 30°C, where the direction of the magnetic field formed an angle of 60° with the plane of the rice layer.

[0038] S3. Soaking: soak the rice after magnetic field treatment in a soaking solution at 5°C for 6 hours; then soak it in a soaking solution at 58°C for 2 hours; the soaking solution includes the following raw materials by mass fraction: 0.1wt% glutamate decarboxylase, 0.2wt% calcium lactate or calcium gluconate, 0.5wt% calcium chloride, 0.2wt% vitamin B6, and the balance is water.

[0039] S4. Ultrasonic assisted germination: The soaked rice was placed in a container, and the volume fraction of CO2 in the container was maintained at 10% for 24 hours before the rice germinated. Then, the container was placed at a frequency of 35 kHz and a power density of 0.3 W / cm 2 The method comprises the following steps: placing the rice in an ultrasonic environment (intermittent mode, with a working cycle of 10 minutes of ultrasonic treatment and 5 minutes of rest), and dynamically introducing a mixed gas containing CO2, O2 and an inert gas into the container, wherein the volume fraction of CO2 is 10%, the volume fraction of O2 is 15%, and the balance is an inert gas; maintaining the temperature of the rice in the container at 28-32°C, ultrasonically inducing germination for 30 hours, and spraying the rice with an aqueous solution of 2 mmol / L of γ-aminobutyric acid, 1 mmol / L of trehalose and 1 mmol / L of proline every 3 hours, with a spray flow rate of 100 mL / min and a spray time of 1 hour.

[0040] When the bud length reaches 1-3 mm, germination is terminated, and the volume fraction of CO2 in the container is reduced to 7% within 24 hours after the end of germination.

[0041] The germinated rice is then vacuum-frozen in two stages: the first stage is pre-frozen at -30°C to -40°C for 4 hours, and the second stage is dried at a vacuum degree of 20Pa and a temperature of -50°C to -60°C for 24 hours; the moisture content of the rice after vacuum freeze-drying is ≤12%.

[0042] S5 steaming: the rice treated in step S4 was steamed at 110-120 ℃ for 15min, and then air-dried;

[0043] S6. Hulling: Hulling and milling the rice after the treatment in step S5 to obtain parboiled rice.

[0044] Example 2

[0045] The parboiled rice of this example was prepared as follows.

[0046] S1. Pretreatment: removing impurities, disinfecting and cleaning the rice in sequence;

[0047] S2. Magnetic field induction: The rice was treated in an alternating pulse magnetic field of 10 mT and 5 Hz for 50 min at 25°C, where the direction of the magnetic field formed an angle of 30° with the plane of the rice layer.

[0048] S3. Soaking: soak the rice after magnetic field treatment in a soaking solution at 10°C for 4 hours; then soak it in a soaking solution at 55°C for 1 hour; the soaking solution includes the following raw materials by mass fraction: 0.05wt% glutamate decarboxylase, 0.1wt% calcium lactate or calcium gluconate, 0.4wt% calcium chloride, 0.1wt% vitamin B6, and the balance is water.

[0049] S4. Ultrasonic assisted germination: The soaked rice was placed in a container, and the volume fraction of CO2 in the container was maintained at 8% for 24 hours before the rice germinated. Then, the container was placed under a frequency of 45 kHz and a power density of 0.8 W / cm 2 The method comprises the following steps: placing the rice grains in an ultrasonic environment (intermittent mode, with a working cycle of 5 minutes of ultrasonication and 2 minutes of rest), and dynamically introducing a mixed gas containing CO2, O2 and an inert gas into the container, wherein the volume fraction of CO2 is 5%, the volume fraction of O2 is 10%, and the balance is an inert gas; keeping the temperature of the rice grains in the container at 30°C, ultrasonically inducing germination for 48 hours, and spraying the rice grains with an aqueous solution of 2 mmol / L of γ-aminobutyric acid, 0.05 mmol / L of trehalose and 0.5 mmol / L of proline every 2 hours, at a spraying flow rate of 200 mL / min, and a spraying time of 1 hour.

[0050] When the bud length reaches 1-3 mm, germination is terminated, and the volume fraction of CO2 in the container is reduced to 5% within 24 hours after the end of germination.

[0051] The germinated rice is dried by vacuum freeze drying in two stages: the first stage is pre-freezing at -30°C to -40°C for 2-4 hours, and the second stage is drying at a vacuum degree of 10-30Pa and a temperature of -50°C to -60°C for 12-24 hours; the moisture content of the rice after vacuum freeze drying is ≤12%.

[0052] S5 steaming: the rice treated in step S4 is steamed at 110-120 ℃ for 10min, and then air-dried;

[0053] S6. Hulling: Hulling and milling the rice after the treatment in step S5 to obtain parboiled rice.

[0054] Example 3

[0055] The parboiled rice of this example was prepared as follows.

[0056] S1. Pretreatment: removing impurities, disinfecting and cleaning the rice in sequence;

[0057] S2. Magnetic field induction: The rice was treated in an alternating pulse magnetic field of 20 mT and 1 Hz for 120 min at 35°C, where the direction of the magnetic field formed an angle of 40° with the plane of the rice layer.

[0058] S3. Soaking: soak the rice after magnetic field treatment in a soaking solution at 15°C for 2 hours; then soak it in a soaking solution at 60°C for 1 hour; the soaking solution includes the following raw materials by mass fraction: 0.01wt% glutamate decarboxylase, 0.05wt% calcium lactate or calcium gluconate, 0.1wt% calcium chloride, 0.05wt% vitamin B6, and the balance is water.

[0059] S4. Ultrasonic assisted germination: The soaked rice was placed in a container, and the volume fraction of CO2 in the container was maintained at 9% for 24 hours before the rice germinated. Then, the container was placed at a frequency of 35 kHz and a power density of 0.8 W / cm 2 The method comprises the following steps: placing the rice grains in an ultrasonic environment (intermittent mode, with a working cycle of 10 minutes of ultrasonic treatment and 2 minutes of stop), and dynamically introducing a mixed gas containing CO2, O2 and an inert gas into the container, wherein the volume fraction of CO2 is 8%, the volume fraction of O2 is 13%, and the balance is an inert gas; keeping the temperature of the rice grains in the container at 30°C, ultrasonically inducing germination for 24 hours, and spraying the rice grains with an aqueous solution of 5 mmol / L of γ-aminobutyric acid, 1 mmol / L of trehalose and 2 mmol / L of proline every hour at a spray flow rate of 50 mL / min; and spraying for 1 hour.

[0060] When the bud length reaches 1-3 mm, germination is terminated, and the volume fraction of CO2 in the container is reduced to 5% within 24 hours after the end of germination.

[0061] The germinated rice is dried by vacuum freeze drying in two stages: the first stage is pre-freezing at -30°C to -40°C for 4 hours, and the second stage is drying at a vacuum degree of 30Pa and a temperature of -50°C to -60°C for 12 hours; the moisture content of the rice after vacuum freeze drying is ≤12%.

[0062] S5 steaming: the rice treated in step S4 was steamed at 110-120 ℃ for 5min, and then air-dried;

[0063] S6. Hulling: Hulling and milling the rice after the treatment in step S5 to obtain parboiled rice.

[0064] Example 4

[0065] The parboiled rice of this example was prepared as follows.

[0066] S1. Pretreatment: removing impurities, disinfecting and cleaning the rice in sequence;

[0067] S2. Magnetic field induction: The rice was treated in an alternating pulse magnetic field of 20 mT and 3 Hz for 80 min at 35°C, where the direction of the magnetic field formed an angle of 30° with the plane of the rice layer.

[0068] S3. Soaking: soak the rice after magnetic field treatment in a soaking solution at 5°C for 2 hours; then soak it in a soaking solution at 58°C for 1.5 hours; the soaking solution includes the following raw materials by mass fraction: 0.08wt% glutamate decarboxylase, 0.15wt% calcium lactate or calcium gluconate, 0.35wt% calcium chloride, 0.15wt% vitamin B6, and the balance is water.

[0069] S4. Ultrasonic assisted germination: The soaked rice was placed in a container, and the volume fraction of CO2 in the container was maintained at 10% for 24 hours before the rice germinated. Then, the container was placed at a frequency of 45 kHz and a power density of 0.5 W / cm 2 The method comprises the following steps: placing the rice in an ultrasonic environment (intermittent mode, with a working cycle of 8 minutes of ultrasonication and 3 minutes of rest), and dynamically introducing a mixed gas containing CO2, O2 and an inert gas into the container, wherein the volume fraction of CO2 is 8%, the volume fraction of O2 is 15%, and the balance is an inert gas; keeping the temperature of the rice in the container at 28°C, ultrasonically inducing germination for 48 hours, and spraying the rice with an aqueous solution of 5 mmol / L of γ-aminobutyric acid, 1 mmol / L of trehalose and 2 mmol / L of proline every 3 hours, with a spraying flow rate of 300 mL / min and a spraying time of 1 hour.

[0070] When the bud length reaches 1-3 mm, germination is terminated, and the volume fraction of CO2 in the container is reduced to 5-7% within 24 hours after the end of germination.

[0071] The germinated rice is dried by vacuum freeze drying in two stages: the first stage is pre-freezing at -30°C to -40°C for 2-4 hours, and the second stage is drying at a vacuum degree of 10-30Pa and a temperature of -50°C to -60°C for 12-24 hours; the moisture content of the rice after vacuum freeze drying is ≤12%.

[0072] S5. Steaming: Steam the rice after treatment in step S4 for 5 to 15 minutes at 110-120°C, and then air-dry;

[0073] S6. Hulling: Hulling and milling the rice after the treatment in step S5 to obtain parboiled rice.

[0074] Example 5

[0075] The parboiled rice of this example was prepared as follows.

[0076] S1. Pretreatment: removing impurities, disinfecting and cleaning the rice in sequence;

[0077] S2. Magnetic field induction: The rice was treated in an alternating pulse magnetic field of 20 mT and 3 Hz for 30 min at 30°C, where the direction of the magnetic field formed an angle of 60° with the plane of the rice layer.

[0078] S3. Soaking: soak the rice after magnetic field treatment in a soaking solution at 15°C for 6 hours; then soak it in a soaking solution at 60°C for 2 hours; the soaking solution includes the following raw materials by mass fraction: 0.05wt% glutamate decarboxylase, 0.05wt% calcium lactate or calcium gluconate, 0.5wt% calcium chloride, 0.2wt% vitamin B6, and the balance is water.

[0079] S4. Ultrasonic assisted germination: The soaked rice was placed in a container, and the volume fraction of CO2 in the container was maintained at 10% for 24 hours before the rice germinated. Then, the container was placed at a frequency of 45 kHz and a power density of 0.5 W / cm 2 The method comprises the following steps: placing the rice in an ultrasonic environment (intermittent mode, with a working cycle of 10 minutes of ultrasonication and 2 minutes of rest), and dynamically introducing a mixed gas containing CO2, O2 and inert gas into the container, wherein the volume fraction of CO2 is 5%, the volume fraction of O2 is 15%, and the balance is inert gas; keeping the temperature of the rice in the container at 32°C, ultrasonically inducing germination for 24 hours, and spraying the rice with an aqueous solution of 3 mmol / L of γ-aminobutyric acid, 1 mmol / L of trehalose and 0.5 mmol / L of proline every 2 hours, with a spray flow rate of 100 mL / min and a spray time of 1 hour.

[0080] When the bud length reaches 1-3 mm, germination is terminated, and the volume fraction of CO2 in the container is reduced to 7% within 24 hours after the end of germination.

[0081] The germinated rice is dried by vacuum freeze drying in two stages: the first stage is pre-freezing at -30°C to -40°C for 2-4 hours, and the second stage is drying at a vacuum degree of 10Pa and a temperature of -50°C to -60°C for 24 hours; the moisture content of the rice after vacuum freeze drying is ≤12%.

[0082] S5 steaming: the rice treated in step S4 was steamed at 110-120 ℃ for 15min, and then air-dried;

[0083] S6. Hulling: Hulling and milling the rice after the treatment in step S5 to obtain parboiled rice.

[0084] Comparative Example 1

[0085] The difference from Example 1 is that the magnetic field induction treatment in step S2 is not performed, and the remaining steps are the same as those in Example 1.

[0086] Comparative Example 2

[0087] The difference from Example 1 is that the low-temperature (5°C) immersion treatment in step S3 is not performed, and the immersion is directly performed at 58°C. The remaining steps are the same as those in Example 1.

[0088] Comparative Example 3

[0089] The difference from Example 1 is that in step S4, ultrasonic treatment is not performed, and the remaining steps are the same as those of Example 1.

[0090] Comparative Example 4

[0091] The difference from Example 1 is that the magnetic field induction treatment in step S2 is not performed, and in step S4, ultrasonic treatment is not performed. The remaining steps are the same as those in Example 1.

[0092] Comparative Example 5

[0093] The difference from Example 1 is that in step S4, no spraying treatment is performed, and the remaining steps are the same as those of Example 1.

[0094] Experimental example

[0095] The rice grains treated with magnetic field induction in Example 1-5 and the rice grains not treated with magnetic field induction (control group) were used as the objects, and the intracellular Ca2+ was detected using Fluo-4 AM fluorescent probe. 2+ The results are shown in Table 1.

[0096] Table 1 Intracellular Ca2+ in each group of rice2+ Concentration (nmol / L)

[0097] Example 1 Example 2 Example 3 Example 4 Example 5 Control group <![CDATA[Ca 2+ Content]]> 220 210 231 224 215 85

[0098] It can be concluded from Table 1 that after the magnetic field induction treatment, the Lorentz force of the alternating magnetic field causes transient micropores (2-5 nm in diameter) in the cell membrane phospholipid bilayer, promoting Ca 2+ internal flow. Ca 2+ After binding to calmodulin (CaM), it activates the downstream MAPK signaling pathway, upregulates GAD gene expression, and increases intracellular Ca 2+ The concentration increased significantly.

[0099] The rice of Examples 1-5 and Comparative Examples 1-5 were used as the objects to detect the contents of γ-aminobutyric acid and reducing sugar in the rice, and the results are shown in Table 2. The data of each group in Table 2 are the average values ​​of 3 samples measured 3 times respectively.

[0100] Table 2 Contents of γ-aminobutyric acid and reducing sugar in various grains

[0101]

[0102]

[0103] It can be concluded from Table 2 that the reducing sugar content in the rice of Examples 1-5 is low, and the content of γ-aminobutyric acid is high. The reducing sugar in the rice can be fully converted into γ-aminobutyric acid. It can be seen that after the combined treatment of pulsed magnetic field, ultrasonic treatment, and low temperature induction, the enrichment of γ-aminobutyric acid in rice can be promoted and the content of γ-aminobutyric acid in the rice can be increased. In Comparative Example 5, no spraying treatment is performed, that is, no exogenous γ-aminobutyric acid is added, and the content of γ-aminobutyric acid in the rice is lower than that in Example 1. It can be seen that by adding an aqueous solution of γ-aminobutyric acid, the external γ-aminobutyric acid enters the rice, further increasing the content of γ-aminobutyric acid in the rice.

[0104] In summary, the preparation method of the parboiled rice rich in γ-aminobutyric acid provided by the present invention combines pulsed magnetic field, low temperature soaking, and ultrasonic treatment to promote rice germination, improve germination efficiency, promote the production of γ-aminobutyric acid in rice, and then increase the content of γ-aminobutyric acid. Among them, the pulsed magnetic field (10-20mT) causes micropores in the cell membrane, and the low temperature (5-15°C) induces the expression of GAD enzyme. The combination of the two increases the activity of GABA synthase by more than 40%; ultrasonic (35-45kHz) treatment can promote the diffusion of metabolites.

[0105] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for preparing parboiled rice rich in γ-aminobutyric acid, characterized in that: The following steps are involved: S1. Pretreatment: removing impurities, disinfecting and cleaning the rice in sequence; S2. Magnetic field induction: The rice was treated in a pulsed magnetic field of 10-20 mT for 30-120 min at 25-35°C; S3. Soaking: Soak the rice after magnetic field treatment in a soaking solution at 5-15°C for 2-6 hours; and then soak in a soaking solution at 55-60°C for 1-2 hours; S4. Ultrasonic assisted germination: The soaked rice is placed in an ultrasonic assisted germination chamber at a frequency of 35-45kHz and a power density of 0.3-0.8W / cm 2 In an ultrasonic environment, ultrasonically induce germination at 28-32°C for 24-48 hours; when the buds reach 1-3 mm in length, terminate germination and vacuum freeze-dry; S5. Steaming: Steam the rice after treatment in step S4 for 5 to 15 minutes at 110-120°C, and then air-dry; S6. Hulling: Hulling and milling the rice after the treatment in step S5 to obtain parboiled rice.

2. The method for preparing parboiled rice rich in γ-aminobutyric acid according to claim 1, characterized in that: The soaking liquid comprises the following raw materials by mass fraction: 0.01-0.1wt% of glutamate decarboxylase, 0.05-0.2wt% of calcium lactate or calcium gluconate, 0.1-0.5wt% of calcium chloride, 0.05-0.2wt% of vitamin B6, and the balance is water.

3. The method for preparing parboiled rice rich in γ-aminobutyric acid according to claim 1, characterized in that: In step S4, the moisture content of the rice after vacuum freeze drying is ≤12%.

4. The method for preparing parboiled rice rich in γ-aminobutyric acid according to claim 1, characterized in that: In the step S4, the ultrasonic induced germination process also includes dynamic gas regulation: a mixed gas containing CO2, O2 and inert gas is introduced into the rice, wherein the volume fraction of CO2 is 5-10%, the volume fraction of O2 is 10-15%, and the balance is inert gas.

5. The method for preparing parboiled rice rich in γ-aminobutyric acid according to claim 4, characterized in that: The volume fraction of CO2 is maintained at 8-10% in the 24 hours before rice germination, and the volume fraction of CO2 is reduced to 5-7% within 24 hours after the germination is completed.

6. The method for preparing parboiled rice rich in γ-aminobutyric acid according to claim 1, characterized in that: In the step S4, during the ultrasonic induced germination process, the method further comprises spraying an aqueous solution of 0.5-5 mmol / L γ-aminobutyric acid, 0.1-1 mmol / L trehalose and 0.5-2 mmol / L proline on the rice every 1-3 hours, with a spraying flow rate of 50-300 mL / min.

7. The method for preparing parboiled rice rich in γ-aminobutyric acid according to claim 1, characterized in that: The pulsed magnetic field in step S2 is an alternating magnetic field with a frequency of 1-5 Hz, and the direction of the magnetic field forms an angle of 30-60° with the plane of the rice layer.

8. The method for preparing parboiled rice rich in γ-aminobutyric acid according to claim 1, characterized in that: The ultrasonic treatment in step S4 is performed in an intermittent mode, and the working cycle is: ultrasonic treatment for 5-10 minutes and rest for 2-5 minutes.

9. The method for preparing parboiled rice rich in γ-aminobutyric acid according to claim 1, characterized in that: The vacuum freeze drying in step S4 includes two stages: the first stage is pre-freezing at -30°C to -40°C for 2-4 hours, and the second stage is drying at a vacuum degree of 10-30Pa and a temperature of -50°C to -60°C for 12-24 hours.

10. A parboiled rice rich in γ-aminobutyric acid, characterized in that: Prepared by the method described in any one of claims 1 to 9.

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