Method for preparing dihydroquercetin from larch sawdust

Abstract

The invention relates to the technical field of dihydroquercetin preparation, in particular to a method for preparing dihydroquercetin from larch sawdust, which comprises the following steps: S1, raw material pretreatment: selecting roots of larch sawdust as a raw material, and pretreating the raw material to obtain a base material; s2, strain preparation: the strain is prepared, and the strain is used for fermentation treatment of the base material. According to the method, the white-rot fungi can rapidly grow and secrete a large amount of enzymes for decomposing lignin substances, so that the decomposition efficiency of larch wood chips is improved, the yield of dihydroquercetin is increased, the culture medium composed of soybean sprout juice, glucose and amino acid provides rich carbon and nitrogen nutrient substances for the white-rot fungi, the growth and metabolism requirements of the white-rot fungi are met, and the yield of the white-rot fungi is increased. The larch sawdust can generate more enzymes to decompose substances in the sawdust and promote the generation of dihydroquercetin, so that the purity and the yield of dihydroquercetin prepared from the larch sawdust are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of dihydroquercetin preparation, and particularly to a method for preparing dihydroquercetin from larch sawdust. Background Art

[0002] Dihydroquercetin belongs to dihydroflavonol compounds, which are colorless needle-shaped crystals or light yellow powders, and are mostly extracted from larch and the like. It has various effects such as antioxidation, immune enhancement, prevention and treatment of cardiovascular and cerebrovascular diseases, etc., and is widely used in industries such as medicine, food, and cosmetics, and is a natural active ingredient with great value.

[0003] In the prior art, when preparing dihydroquercetin from larch sawdust, due to the high density of larch and its relatively compact fiber structure, the contact between the extraction solvent and dihydroquercetin is hindered, resulting in a low extraction rate of dihydroquercetin. Based on this, the present invention provides a method for preparing dihydroquercetin from larch sawdust. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing dihydroquercetin from larch sawdust. The dihydroquercetin prepared by the method for preparing dihydroquercetin from larch sawdust of the present invention not only has good purity performance but also has excellent yield performance.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A method for preparing dihydroquercetin from larch sawdust, comprising the following steps: S1: Raw material pretreatment, selecting the root part of larch sawdust as the raw material, and obtaining a base material after the raw material is pretreated; S2: Strain preparation, preparing a strain, which is used for fermenting the base material; S3: Fermentation treatment, mixing the base material and the strain for fermentation treatment to obtain an extraction material; S4: Activation treatment, performing activation treatment on the extraction material to obtain a preparation material; S5: Reaction preparation, performing reaction extraction treatment on the preparation material to obtain dihydroquercetin.

[0006] Further, the method of the raw material pretreatment is: the raw material enters clean water for soaking treatment for 4 - 6 h, after the soaking is completed, crushing treatment is carried out, and the crushing particle size is 8 - 14 mm to obtain a granular material. The granular material is sent into an oven, and the oven is set at 38 - 42 °C for drying treatment for 20 - 30 min to obtain the base material.

[0007] Further, the strain is prepared by the following method: The spores of white rot fungi are scraped into sterile water to obtain a bacterial solution. The bacterial solution is added to a culture medium and cultured under the conditions of a temperature of 30 - 34 °C and a humidity of 70 - 80% for 40 - 50 h to obtain the strain.

[0008] Furthermore, the mass of the white rot fungus is 0.6-0.8% of the mass of the sterile water, and the mass of the culture medium is 3-5 times the mass of the bacterial liquid.

[0009] Furthermore, the culture medium is prepared by the following method: select fresh soybean sprouts, send the fresh soybean sprouts into a blender for juicing, filter after juicing to obtain soybean sprout juice, add glucose and amino acids to the soybean sprout juice, and let it stand for 10-20 h to obtain the culture medium. Among them, the mass of glucose is 4-6% of the mass of the soybean sprout juice, and the mass of amino acids is 6-8% of the mass of the soybean sprout juice.

[0010] Furthermore, the method of the fermentation treatment is as follows: add the strain into a sprayer, spread the base material flat, evenly spray the strain on the surface of the base material, place the base material after spraying the strain in a dark place, keep the temperature at 28-30 °C, and let it stand for fermentation treatment for 8-10 d. During the fermentation treatment process, turn it over every 4-6 h. After the fermentation treatment is completed, send the obtained product into an oven, set the oven to preheat to 100-110 °C, keep it warm and dry for 5-7 min, crush the obtained product, and the crushing particle size is 2-4 mm. After the fermentation treatment is completed, an extraction material is prepared.

[0011] Furthermore, the mass of the strain is 6-8% of the mass of the base material.

[0012] Furthermore, the method of the activation treatment is as follows: add the extraction material into a reaction kettle, add sodium hydroxide and deionized water into the reaction kettle, set the reaction kettle to heat up to 50-60 °C, set the stirring speed to 200-300 r / min, set to keep warm and stir for 20-30 min. After stirring, filter to remove the liquid to obtain a solid. Add a dilute hydrochloric acid solution to the solid to adjust the pH value to 7-7.2, then rinse with deionized water. After rinsing, send it into an oven, and set the oven to dry at 55-65 °C for 2-4 h. After the activation treatment is completed, a preparation material is prepared. Among them, the mass of sodium hydroxide is 4-6% of the mass of the extraction material, and the mass of deionized water is 8-10 times the mass of sodium hydroxide.

[0013] Furthermore, the method of the reaction preparation is as follows: mix the preparation material with an ethanol solution and add it into a reaction kettle. Set the pressure of the reaction kettle to 3-4 MP and the temperature to 100-140 °C, and react for 40-50 min. After the reaction product is cooled to room temperature, filter it. Filter the obtained solid and react again. The reaction pressure is 1.8-2.4 MP and the temperature is 110-130 °C, and react for 2-4 h. Filter the reaction product. Filter the obtained liquid material through a chromatography column at 90-100 °C. Then inject glycerol with a volume concentration of 95% at 80 °C into the chromatography column for elution to obtain an eluate. Distill and crystallize the eluate to obtain dihydroquercetin.

[0014] Further, the mass concentration of the ethanol solution is 40-60%, and the mass of the ethanol solution is 8-10 times that of the preparation material.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In the present invention, through the fermentation treatment of the raw materials during the preparation of dihydroquercetin, when fermenting the roots of larch sawdust, white rot fungi can grow rapidly and secrete a large amount of enzymes that decompose lignin substances, thereby improving the decomposition efficiency of larch sawdust, increasing the output of dihydroquercetin. The culture medium composed of soybean sprout juice, glucose, and amino acids provides rich carbon and nitrogen nutrients for white rot fungi, meeting their growth and metabolic needs, enabling them to produce more enzymes to decompose the substances in the sawdust, promoting the formation of dihydroquercetin, and effectively improving the purity and yield of dihydroquercetin prepared from larch sawdust. 2. In the present invention, through the activation treatment of the raw materials, the addition of sodium hydroxide can damage the fiber structure of the raw materials, making dihydroquercetin easier to release from the fiber network structure, further improving the extraction rate of dihydroquercetin during the extraction process. Specific Embodiments

[0016] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0017] Among them, it should be noted that the raw materials used in the following embodiments are all commercially available raw materials.

[0018] Example 1: S1: Pretreatment of raw materials. Select the roots of larch sawdust as raw materials, and the raw materials are pretreated to obtain a base material. S2: Preparation of strains. Prepare strains, which are used for fermenting the base material. S3: Fermentation treatment. The base material and the strains are mixed for fermentation treatment to obtain an extraction material. S4: Activation treatment. The extraction material is subjected to activation treatment to obtain a preparation material. S5: Reaction preparation. The preparation material is subjected to reaction extraction treatment to obtain dihydroquercetin.

[0019] Further, the method for pretreating the raw materials is as follows: The raw materials are soaked in clean water for 4 h, and after soaking, they are subjected to crushing treatment. The crushing particle size is 8 mm to obtain granular materials. The granular materials are sent into an oven, and the oven is set at 38 °C for drying treatment for 20 min to obtain a base material.

[0020] Further, the bacterial strain is prepared by the following method: The spores of white rot fungi are scraped into sterile water to obtain a bacterial solution. The bacterial solution is added to a culture medium and cultured at a temperature of 30 °C and a humidity of 70% for 40 h to obtain the bacterial strain.

[0021] Further, the mass of the white rot fungi is 0.6% of the mass of the sterile water, and the mass of the culture medium is 3 times the mass of the bacterial solution.

[0022] Further, the culture medium is prepared by the following method: Select fresh soybeansprouts. The fresh soybeansprouts are sent into a blender for juicing. After juicing, filtration is carried out to obtain soybean sprout juice. Glucose and amino acids are added to the soybean sprout juice, and it is left standing for 10 h to obtain the culture medium. Among them, the mass of glucose is 4% of the mass of the soybean sprout juice, and the mass of amino acids is 6% of the mass of the soybean sprout juice.

[0023] Further, the method of fermentation treatment is as follows: The bacterial strain is added into a sprayer. After the base material is laid flat, the bacterial strain is evenly sprayed on the surface of the base material. The base material after the bacterial strain spraying is placed in a dark place, the temperature is maintained at 28 °C, and it is left standing for fermentation treatment for 8 d. During the fermentation treatment process, turning treatment is carried out at an interval of 4 h. After the fermentation treatment is completed, the obtained product is sent into an oven. The oven is set to preheat to 100 °C and keep warm for drying treatment for 5 min. The obtained product is subjected to crushing treatment, and the crushing particle size is 2 mm. After the fermentation treatment is completed, the extracted material is obtained.

[0024] Further, the mass of the bacterial strain is 6% of the mass of the base material.

[0025] Further, the method of activation treatment is as follows: The extracted material is added into a reaction kettle. Sodium hydroxide and deionized water are added to the reaction kettle. The reaction kettle is set to heat up to 50 °C, the stirring speed is set to 200 r / min, and it is set to keep warm and stir for 20 min. After stirring, the liquid is filtered off to obtain a solid. Dilute hydrochloric acid solution is added to the solid to adjust the pH value to 7. Then it is rinsed with deionized water. After the rinsing is completed, it is sent into an oven. The oven is set to dry at 55 °C for 2 h. After the activation treatment is completed, the preparation material is obtained. Among them, the mass of sodium hydroxide is 4% of the mass of the extracted material, and the mass of deionized water is 8 times the mass of sodium hydroxide.

[0026] Further, the method of reaction preparation is as follows: The preparation material and an ethanol solution are mixed and added into a reaction kettle. The reaction kettle is set to a pressure of 3 MP and a temperature of 100 °C, and the reaction is carried out for 40 min. The product obtained from the reaction is cooled to room temperature and then filtered. The solid obtained by filtration is reacted again. The reaction pressure is 1.8 MP and the temperature is 110 °C, and the reaction is carried out for 2 h. The product obtained from the reaction is subjected to filtration treatment. The liquid material obtained by filtration passes through a chromatography column at 90 °C. Then glycerol with a volume concentration of 95% at 80 °C is injected into the chromatography column for elution to obtain an eluate. The eluate is subjected to distillation and crystallization treatment to obtain dihydroquercetin.

[0027] Furthermore, the mass concentration of the ethanol solution is 40%, and the mass of the ethanol solution is 8 times that of the preparation material.

[0028] Example Two: S1: Raw material pretreatment. Select the root part of larch sawdust as the raw material. After the raw material is pretreated, a base material is obtained. S2: Strain preparation. Prepare a strain, which is used to ferment the base material. S3: Fermentation treatment. The base material and the strain are mixed for fermentation treatment to obtain an extraction material. S4: Activation treatment. The extraction material is subjected to activation treatment to obtain a preparation material. S5: Reaction preparation. The preparation material is subjected to reaction extraction treatment to obtain dihydroquercetin.

[0029] Furthermore, the method of raw material pretreatment is as follows: The raw material enters clean water for soaking treatment for 5 h. After soaking, it is subjected to crushing treatment, and the crushing particle size is 11 mm to obtain granular material. The granular material is sent into an oven, and the oven is set at 40 °C for drying treatment for 25 min to obtain the base material.

[0030] Furthermore, the strain is prepared by the following method: The spores of white rot fungus are scraped into sterile water to obtain a bacterial solution. The bacterial solution is added to a culture medium and cultured at a temperature of 32 °C and a humidity of 75% for 45 h to obtain the strain.

[0031] Furthermore, the mass of white rot fungus is 0.7% of the mass of sterile water, and the mass of the culture medium is 4 times that of the bacterial solution.

[0032] Furthermore, the culture medium is prepared by the following method: Select fresh soybean sprouts. The fresh soybean sprouts are sent into a blender for juicing treatment. After juicing treatment, filtration is carried out to obtain soybean sprout juice. Glucose and amino acids are added to the soybean sprout juice and left standing for 15 h to obtain the culture medium. Among them, the mass of glucose is 5% of the mass of soybean sprout juice, and the mass of amino acids is 7% of the mass of soybean sprout juice.

[0033] Furthermore, the method of fermentation treatment is as follows: The strain is added into a sprayer. After the base material is laid flat, the strain is evenly sprayed on the surface of the base material. After the spraying of the strain, the base material is placed in a dark place, the temperature is kept at 29 °C, and static fermentation treatment is carried out for 9 d. During the fermentation treatment process, turning treatment is carried out at intervals of 5 h. After the fermentation treatment is completed, the obtained product is sent into an oven, and the oven is set to be preheated to 105 °C and kept warm for drying treatment for 6 min. The obtained product is subjected to crushing treatment, and the crushing particle size is 3 mm. After the fermentation treatment is completed, the extraction material is obtained.

[0034] Furthermore, the mass of the strain is 7% of the mass of the base material.

[0035] Further, the activation treatment method is as follows: The extraction material is added into a reaction kettle, sodium hydroxide and deionized water are added into the reaction kettle, the temperature of the reaction kettle is set to rise to 55 °C, the stirring speed is set to 250 r / min, the heat preservation and stirring treatment is set for 25 min. After the stirring is completed, the liquid is filtered off to obtain a solid material. A dilute hydrochloric acid solution is added to the solid material, and the pH value is adjusted to 7.1. Then, it is rinsed with deionized water. After the rinsing is completed, it is sent into an oven, and the oven is set for drying treatment at 60 °C for 3 h to complete the activation treatment and obtain the preparation material. Among them, the mass of sodium hydroxide is 5% of the mass of the extraction material, and the mass of deionized water is 9 times the mass of sodium hydroxide.

[0036] Further, the reaction preparation method is as follows: The preparation material and an ethanol solution are mixed and added into a reaction kettle. The pressure of the reaction kettle is set to 3.5 MP, the temperature is 120 °C, and the reaction treatment is carried out for 45 min. After the product obtained from the reaction is cooled to room temperature, it is subjected to filtration treatment. The solid obtained by filtration is reacted again. The reaction pressure is 2.1 MP, the temperature is 120 °C, and the reaction treatment is carried out for 3 h. The product obtained from the reaction is subjected to filtration treatment, and the liquid material obtained by filtration passes through a chromatography column at 95 °C. Then, glycerol with a volume concentration of 95% at 80 °C is injected into the chromatography column for elution to obtain an eluate. The eluate is subjected to distillation and crystallization treatment to obtain dihydroquercetin.

[0037] Further, the mass concentration of the ethanol solution is 50%, and the mass of the ethanol solution is 9 times the mass of the preparation material.

[0038] Example 3: S1: Raw material pretreatment, selecting the root of larch sawdust as the raw material, and obtaining the base material after the raw material is pretreated. S2: Strain preparation, preparing the strain, and the strain is used for fermenting the base material. S3: Fermentation treatment, mixing the base material and the strain for fermentation treatment to obtain the extraction material. S4: Activation treatment, performing activation treatment on the extraction material to obtain the preparation material. S5: Reaction preparation, performing reaction extraction treatment on the preparation material to obtain dihydroquercetin.

[0039] Further, the raw material pretreatment method is as follows: The raw material enters clean water for soaking treatment for 6 h. After the soaking is completed, it is subjected to crushing treatment, and the crushing particle size is 14 mm to obtain particle material. The particle material is sent into an oven, and the oven is set for drying treatment at 42 °C for 30 min to obtain the base material.

[0040] Further, the strain is obtained by the following method: The spores of white rot fungi are scraped into sterile water to obtain a bacterial solution. The bacterial solution is added into a culture medium and cultured under the conditions of a temperature of 34 °C and a humidity of 80% for 50 h to obtain the strain.

[0041] Furthermore, the mass of the white rot fungus is 0.8% of the mass of the sterile water, and the mass of the culture medium is 5 times the mass of the bacterial liquid.

[0042] Furthermore, the culture medium is prepared by the following method: Select fresh soybeansprouts, send the fresh soybeansprouts into a blender for juicing, filter after juicing to obtain soybean sprout juice, add glucose and amino acids to the soybean sprout juice, and let it stand for 20 h to prepare the culture medium. Among them, the mass of glucose is 6% of the mass of the soybean sprout juice, and the mass of amino acids is 8% of the mass of the soybean sprout juice.

[0043] Furthermore, the method of fermentation treatment is as follows: Add the bacterial strain into a sprayer. After spreading the base material flat, evenly spray the bacterial strain on the surface of the base material. After spraying the bacterial strain, place the base material in a dark place, keep the temperature at 30 °C, and let it stand for fermentation treatment for 10 d. During the fermentation treatment process, turn it over every 6 h. After completing the fermentation treatment, send the obtained product into an oven, set the oven to preheat to 110 °C, keep it warm and dry for 7 min, and crush the obtained product. The crushing particle size is 4 mm to complete the fermentation treatment and obtain the extraction material.

[0044] Furthermore, the mass of the bacterial strain is 6-8% of the mass of the base material.

[0045] Furthermore, the method of activation treatment is as follows: Add the extraction material into a reaction kettle, add sodium hydroxide and deionized water to the reaction kettle, set the reaction kettle to heat up to 60 °C, set the stirring speed to 300 r / min, set the heat preservation and stirring treatment for 30 min. After stirring, filter to remove the liquid to obtain a solid. Add a dilute hydrochloric acid solution to the solid to adjust the pH value to 7.2, then rinse with deionized water. After rinsing, send it into an oven, set the oven to dry at 65 °C for 4 h to complete the activation treatment and obtain the preparation material. Among them, the mass of sodium hydroxide is 6% of the mass of the extraction material, and the mass of deionized water is 10 times the mass of sodium hydroxide.

[0046] Furthermore, the method of reaction preparation is as follows: Mix the preparation material with an ethanol solution and add it into a reaction kettle. Set the pressure of the reaction kettle to 4 MP and the temperature to 140 °C, and carry out the reaction treatment for 50 min. After the reaction product is cooled to room temperature, filter it. Filter the obtained solid and react again. The reaction pressure is 2.4 MP and the temperature is 130 °C, and the reaction treatment is carried out for 4 h. Filter the reaction product. Filter the obtained liquid material through a chromatography column at 100 °C, and then inject glycerol with a volume concentration of 95% at 80 °C into the chromatography column for elution to obtain an eluate. The eluate is subjected to distillation and crystallization treatment to obtain dihydroquercetin.

[0047] Furthermore, the mass concentration of the ethanol solution is 60%, and the mass of the ethanol solution is 10 times the mass of the preparation material.

[0048] Comparative Example 1. The difference between this comparative example and Example 1 is that: this comparative example does not contain covering material.

[0049] Comparative Example 2. The difference between this comparative example and Example 1 is that: this comparative example does not perform the treatment of soaking in the film-forming solution.

[0050] Comparative Example 3. The difference between this comparative example and Example 1 is that: vanadyl sulfate is not added when preparing the film-forming solution in this comparative example.

[0051] Comparative Example 4. The difference between this comparative example and Example 1 is that: this comparative example does not perform the treatment of soaking solution.

[0052] Performance test: Perform performance tests on the dihydroquercetin prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4. The obtained test data are recorded in the following table:

[0053] In the performance test, perform purity tests on the dihydroquercetin prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4, weigh the weight of the dihydroquercetin prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4, and record the weight of its raw materials before preparation at the same time to obtain the yield data.

[0054] It can be seen that the purity performance and yield data of the methods for preparing dihydroquercetin from larch sawdust in Comparative Examples 1, 2, 3, and 4 are all lower than those in Examples 1, 2, and 3; this shows that: through the fermentation treatment of the raw materials during the preparation of dihydroquercetin, when fermenting the roots of larch sawdust, white rot fungi can grow rapidly and secrete a large amount of enzymes that decompose lignin substances, thereby improving the decomposition efficiency of larch sawdust and increasing the output of dihydroquercetin. The culture medium composed of soybean sprout juice, glucose, and amino acids provides rich carbon and nitrogen nutrients for white rot fungi, meets their growth and metabolic needs, enables them to produce more enzymes to decompose the substances in the sawdust, promotes the generation of dihydroquercetin, and further effectively improves the purity and yield of dihydroquercetin prepared from larch sawdust. Through the activation treatment of the raw materials, the addition of sodium hydroxide can destroy the fiber structure of the raw materials, making dihydroquercetin easier to release from the fiber grid structure, and further improving the extraction rate of dihydroquercetin during the extraction process.

[0055] By comparing and analyzing the relevant data in the table, it can be known that the dihydroquercetin prepared by the method of preparing dihydroquercetin from larch sawdust in the present invention not only has good purity performance but also has excellent yield performance. This shows that the method for preparing dihydroquercetin from larch sawdust provided by the present invention has a broader market prospect and is more suitable for promotion.

[0056] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0057] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A method for preparing dihydroquercetin from larch sawdust, characterized in that: It includes the following steps: S1: Pretreatment of raw materials. Select the roots of larch sawdust as raw materials. After pretreatment of the raw materials, a base material is obtained. S2: Preparation of strains. Strains are prepared and used for fermenting the base material. S3: Fermentation treatment. The base material and the strains are mixed for fermentation treatment to obtain an extraction material. S4: Activation treatment. The extraction material is subjected to activation treatment to obtain a preparation material. S5: Reaction preparation. The preparation material is subjected to reaction extraction treatment to obtain dihydroquercetin.

2. The method for preparing dihydroquercetin from larch sawdust according to claim 1, characterized in that, The method for pretreatment of the raw materials is as follows: The raw materials are soaked in clear water for 4 - 6 h. After soaking, they are crushed to a particle size of 8 - 14 mm to obtain granular materials. The granular materials are sent into an oven, and the oven is set at 38 - 42 °C for drying treatment for 20 - 30 min to obtain the base material.

3. The method for preparing dihydroquercetin from larch sawdust according to claim 1, characterized in that, The strains are obtained by the following method: The spores of white rot fungi are scraped into sterile water to obtain a bacterial solution. The bacterial solution is added to a culture medium and cultured at a temperature of 30 - 34 °C and a humidity of 70 - 80% for 40 - 50 h to obtain the strains.

4. The method for preparing dihydroquercetin from larch sawdust according to claim 3, characterized in that, The mass of the white rot fungi is 0.6 - 0.8% of the mass of the sterile water, and the mass of the culture medium is 3 - 5 times the mass of the bacterial solution.

5. The method for preparing dihydroquercetin from larch sawdust according to claim 3, characterized in that, The culture medium is obtained by the following method: Select fresh soybeansprouts. The fresh soybeansprouts are sent into a blender for juicing. After juicing, they are filtered to obtain soybeansprout juice. Glucose and amino acids are added to the soybeansprout juice and left standing for 10 - 20 h to obtain the culture medium. Among them, the mass of glucose is 4 - 6% of the mass of the soybeansprout juice, and the mass of amino acids is 6 - 8% of the mass of the soybeansprout juice.

6. The method for preparing dihydroquercetin from larch sawdust according to claim 1, characterized in that, The method for fermentation treatment is as follows: The strains are added into a sprayer. After the base material is laid flat, the strains are evenly sprayed on the surface of the base material. After spraying the strains, the base material is placed in a dark place at a temperature maintained at 28 - 30 °C and left standing for fermentation treatment for 8 - 10 d. During the fermentation treatment process, it is turned over every 4 - 6 h. After the fermentation treatment is completed, the obtained product is sent into an oven, and the oven is set to be preheated to 100 - 110 °C and kept warm for drying treatment for 5 - 7 min. The obtained product is crushed to a particle size of 2 - 4 mm to complete the fermentation treatment and obtain the extraction material.

7. The method for preparing dihydroquercetin from larch sawdust according to claim 1, characterized in that, The mass of the strains is 6 - 8% of the mass of the base material.

8. The method for preparing dihydroquercetin from larch sawdust according to claim 1, characterized in that, The method for activation treatment is as follows: The extraction material is added into a reaction kettle. Sodium hydroxide and deionized water are added to the reaction kettle. The reaction kettle is set to heat up to 50 - 60 °C, the stirring speed is set at 200 - 300 r / min, and it is set for heat preservation and stirring treatment for 20 - 30 min. After stirring is completed, the liquid is filtered off to obtain a solid. Dilute hydrochloric acid solution is added to the solid to adjust the pH value to 7 - 7.2, and then it is rinsed with deionized water. After rinsing is completed, it is sent into an oven, and the oven is set at 55 - 65 °C for drying treatment for 2 - 4 h to complete the activation treatment and obtain the preparation material. Among them, the mass of sodium hydroxide is 4 - 6% of the mass of the extraction material, and the mass of deionized water is 8 - 10 times the mass of sodium hydroxide.

9. The method for preparing dihydroquercetin from larch sawdust according to claim 1, characterized in that, The method for the reaction preparation is as follows: The preparation material is mixed with an ethanol solution and added into a reaction kettle. The set pressure of the reaction kettle is 3 - 4 MPa, the temperature is 100 - 140 °C, and the reaction is carried out for 40 - 50 min. After the reaction product is cooled to room temperature, it is filtered. The solid obtained by filtration is reacted again. The reaction pressure is 1.8 - 2.4 MPa, the temperature is 110 - 130 °C, and the reaction is carried out for 2 - 4 h. The reaction product is filtered. The liquid material obtained by filtration passes through a chromatography column at 90 - 100 °C. Then, glycerol with a volume concentration of 95% at 80 °C is injected into the chromatography column for elution to obtain an eluate. The eluate is subjected to distillation and crystallization treatment to obtain dihydroquercetin.

10. The method for preparing dihydroquercetin from larch sawdust according to claim 9, characterized in that, The mass concentration of the ethanol solution is 40 - 60%, and the mass of the ethanol solution is 8 - 10 times that of the preparation material.

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