Method for reducing content of tannin in sorghum grains

Abstract

The invention discloses a method for reducing the content of tannin in sorghum grains, which comprises the following steps: (1) mixing soybean milk with sweet distiller's yeast, uniformly stirring, placing in a transparent container, and sealing and fermenting at room temperature for 7-10 days; (2) filtering, and collecting filtrate for later use; (3) diluting the filtrate, uniformly spraying the diluted filtrate to ears of sorghum at the grain filling stage of the sorghum, spraying once every 7-10 days, and spraying for 2-3 times in total; and (4) carrying out other conventional management, harvesting, drying in the sun, threshing and detecting the tannin content when the sorghum grains are mature and present the inherent color of the variety. According to the method, the soybean milk and the sweet distiller's yeast are fermented to form the fermentation liquor, and the fermentation liquor is used as a biological source and is sprayed to the sorghum ears, so that the tannin content in the sorghum grains is reduced, the effect is remarkable, the problems of high breeding cost and long period in the prior art are solved, and a new thought can be provided for controlling the tannin content of the sorghum grains.

Description

Technical Field

[0001] The invention belongs to the technical field of reducing the tannin content in crop grains, and particularly relates to a method for reducing the tannin content in sorghum grains. Background Art

[0002] Tannin is an important chemical component in sorghum grains. It is a complex high-molecular polyphenol compound. The right amount of tannin can inhibit harmful microorganisms in the sorghum fermentation process and generate polyphenol compounds, giving sorghum wine a unique flavor. Excessive tannin has a convergence effect, can coagulate protein, and affect the normal saccharification and fermentation process. Therefore, the appropriate tannin content in sorghum is the key to the quality of sorghum wine.

[0003] The tannin content in sorghum grains is an important condition that affects the flavor of sorghum wine. At present, the tannin content in the grains of some special wine sorghum varieties is relatively high, and the flavor of the wine needs to be improved. In the existing technology, chemical treatment is used to reduce the tannin content. For example, soaking sorghum grains in sodium hydroxide or potassium hydroxide solution can significantly reduce the tannin content. Although the treatment method is simple, sodium hydroxide or potassium hydroxide is a strong alkali with residues, which not only affects other nutrients in sorghum, but also poses certain challenges to the environment and operator safety. This method is not advisable for the field of food production; in the existing technology, new special wine varieties with moderate tannin content can also be selected through sorghum quality breeding, or exogenous conditions can be used to improve sorghum growth and development conditions to reduce the tannin content of sorghum grains. However, the sorghum breeding cycle is long, requires continuous scientific and technological investment, and has high costs. Therefore, exploring a safe and efficient exogenous improvement method to reduce the tannin content in sorghum grains is crucial for the production of wine sorghum, the improvement of wine flavor, and the high-quality development of the wine industry. Summary of the invention

[0004] In view of the defects of the prior art, the present invention provides a method for reducing the tannin content in sorghum grains. By spraying fermentation liquid on the ear of sorghum during the grain filling period, the tannin content in the grains can be effectively reduced. The operation is simple and the cost is low.

[0005] A method for reducing tannin content in sorghum grains comprises the following steps: (1) Mix soybean milk and sweet wine koji, stir evenly, place in a transparent container, and seal and ferment at room temperature for 7-10 days; (2) Filter and collect the filtrate for later use; (3) After diluting the above filtrate, spray it evenly on the sorghum ear during the grain filling period, once every 7-10 days, for a total of 2-3 times; (4) Other procedures are as per normal. When the sorghum grains are mature and have the inherent color of the variety, they are harvested, dried, threshed, and tested for tannin content.

[0006] Preferably, the soybean milk is prepared by the following method: mixing soybeans and water in a mass ratio of 1:(12-15), soaking for 10-12 hours, grinding, filtering out residues, boiling, and cooling to room temperature.

[0007] Preferably, the mass ratio of the soybean milk to the sweet wine koji is (270-350):1.

[0008] Preferably, in step (3), the filtrate is diluted 100-300 times.

[0009] Preferably, in step (3), the diluted filtrate is sprayed at a rate of 25-30 kg / mu each time.

[0010] Preferably, in step (4), the sorghum grains are dried until the moisture content is ≤13%.

[0011] Advantages of the present invention: (1) After fermentation, soybean milk can degrade macromolecular substances such as protein, fat, vitamins, riboflavin, isoflavones and mineral elements into small molecular substances. When sprayed during the sorghum filling period, it is easily absorbed and can improve the nutritional components of sorghum grains and inhibit the accumulation of tannins during the filling process, thereby reducing the tannin content in sorghum grains. The effect is significant. (2) The present invention ferments soybean milk and sweet wine koji to form a fermentation liquid, which is used as a biological source and sprayed on the sorghum ear, which is safe, efficient and pollution-free; (3) The method provided by the present invention is simple and easy to operate, and has low cost. It solves the problems of high breeding cost and long breeding cycle in the prior art, and can provide a new idea for controlling the tannin content of sorghum grains. DETAILED DESCRIPTION

[0012] The sweet wine koji used in the embodiment of the present invention is Angel sweet wine koji.

[0013] Example 1 In 2024, at the experimental base of Baoji Academy of Agricultural Sciences in Liujiayuan, Qishan County, Baoji City, the sorghum variety was Hongdianzi, sown in spring, and treated by the method provided by the present invention and the conventional method (no treatment, i.e. no spraying during the grain filling period, and other management of sorghum was the same as the present invention). The method provided by the present invention is as follows: A method for reducing tannin content in sorghum grains comprises the following steps: (1) Soybeans and water were mixed in a mass ratio of 1:12, soaked for 11 hours, ground, filtered out the residue, boiled, and cooled to room temperature to obtain soybean milk; the soybean milk and sweet wine koji were mixed in a mass ratio of 300:1, stirred evenly, placed in a transparent container, and sealed and fermented at room temperature for 8 days; (2) Filter and collect the filtrate for later use; (3) Dilute the above filtrate 200 times with water and spray it evenly on the sorghum ears during the grain filling period. Spray once every 8 days. The spraying amount of the diluted filtrate is 25 kg / mu each time, and spray 3 times in total. (4) Other routine management was followed. When the sorghum grains were mature and showed the inherent color of the variety, they were harvested and dried until the moisture content of the sorghum grains was 10%. They were threshed and the tannin content in the sorghum grains was measured using a near-infrared grain quality analyzer (DA7250). The measurements were repeated three times and the average value was taken. The test results are shown in Table 1.

[0014] Table 1 Tannin content of sorghum grains treated with the present invention and conventional methods in Example 1 The results showed that, for red dianzi, the average tannin content of sorghum grains by the method provided by the present invention was 1.14%, while the tannin content of sorghum grains by the conventional method was 1.24%. Compared with the conventional method, the tannin content of sorghum grains by the method provided by the present invention was reduced by 8.06%, and the effect was significant.

[0015] Example 2 In 2024, at the Xifeng Liquor Sorghum Planting Base in Liulin Town, Fengxiang District, Baoji City, the sorghum variety is Liaoza 19, sown in spring, and treated by the method provided by the present invention and the conventional method (no treatment, i.e. no spraying during the grain filling period, and other management of sorghum is the same as the present invention). The method provided by the present invention is as follows: A method for reducing tannin content in sorghum grains comprises the following steps: (1) Soybeans and water are mixed in a mass ratio of 1:15, soaked for 10 hours, ground, filtered to remove residue, boiled, and cooled to room temperature to obtain soybean milk; Soybean milk and sweet wine koji are mixed in a mass ratio of 270:1, stirred evenly, placed in a transparent container, and sealed and fermented at room temperature for 7 days; (2) Filter and collect the filtrate for later use; (3) Dilute the above filtrate 100 times with water and spray it evenly on the sorghum ears during the grain filling period. Spray once every 7 days. The spraying amount of the diluted filtrate is 30 kg / mu each time, and spray a total of 3 times; (4) Other routine management was followed. When the sorghum grains were mature and showed the inherent color of the variety, they were harvested and dried until the moisture content of the sorghum grains was 10%. They were threshed and the tannin content in the sorghum grains was measured using a near-infrared grain quality analyzer (DA7250). The measurements were repeated three times and the average value was taken. The test results are shown in Table 2.

[0016] Table 2 Tannin content of sorghum grains treated with the present invention and conventional methods in Example 2 The results showed that, for Liaoza 19, the average tannin content of sorghum grains by the method provided by the present invention was 0.85%, while the tannin content of sorghum grains by the conventional method was 1.16%. Compared with the conventional method, the tannin content of sorghum grains by the method provided by the present invention was reduced by 26.72%, and the effect was significant.

[0017] Example 3 In 2024, at the Qinliang Agricultural Sorghum Planting Base in Liulin Town, Fengxiang District, Baoji City, the sorghum variety is Longza 41, sown in summer, and the method provided by the present invention and the conventional method (no treatment, that is, no spraying during the grain filling period, and other management of sorghum is the same as the present invention) are used for treatment. The method provided by the present invention is as follows: A method for reducing tannin content in sorghum grains comprises the following steps: (1) Soybeans and water are mixed in a mass ratio of 1:14, soaked for 12 hours, ground, filtered to remove residue, boiled, and cooled to room temperature to obtain soybean milk; Soybean milk and sweet wine koji are mixed in a mass ratio of 350:1, stirred evenly, placed in a transparent container, and sealed and fermented at room temperature for 10 days; (2) Filter and collect the filtrate for later use; (3) Dilute the above filtrate 300 times with water and spray it evenly on the sorghum ears during the grain filling period. Spray once every 10 days. The spraying amount of the diluted filtrate is 28 kg / mu each time, and spray twice in total. (4) Other routine management was followed. When the sorghum grains were mature and showed the inherent color of the variety, they were harvested and dried until the moisture content of the sorghum grains was 10%. They were threshed and the tannin content in the sorghum grains was measured using a near-infrared grain quality analyzer (DA7250). The measurements were repeated three times and the average value was taken. The test results are shown in Table 3.

[0018] Table 3 Tannin content of sorghum grains treated with the present invention and conventional methods in Example 3 The results showed that, for Longza 41, the average tannin content of sorghum grains by the method provided by the present invention was 0.96%, while the tannin content of sorghum grains by the conventional method was 1.06%. Compared with the conventional method, the tannin content of sorghum grains by the method provided by the present invention was reduced by 9.43%, and the effect was significant.

Claims

1. A method for reducing tannin content in sorghum grains, characterized in that: The following steps are involved: (1) Mix soybean milk and sweet wine koji, stir evenly, place in a transparent container, and seal and ferment at room temperature for 7-10 days; (2) Filter and collect the filtrate for later use; (3) After diluting the above filtrate, spray it evenly on the sorghum ear during the grain filling period, once every 7-10 days, for a total of 2-3 times; (4) Other procedures are as per normal. When the sorghum grains are mature and have the inherent color of the variety, they are harvested, dried, threshed, and tested for tannin content.

2. The method for reducing tannin content in sorghum grains according to claim 1, characterized in that: The soybean milk is prepared by the following method: mixing soybeans and water in a mass ratio of 1:(12-15), soaking for 10-12 hours, grinding, filtering out residues, boiling, and cooling to room temperature.

3. The method for reducing tannin content in sorghum grains according to claim 2, characterized in that: The mass ratio of the soybean milk to the sweet wine koji is (270-350):

1.

4. The method for reducing tannin content in sorghum grains according to claim 3, characterized in that: In step (3), the filtrate is diluted 100-300 times.

5. The method for reducing tannin content in sorghum grains according to claim 4, characterized in that: In step (3), the diluted filtrate is sprayed at a rate of 25-30 kg / mu each time.

6. The method for reducing tannin content in sorghum grains according to claim 5, characterized in that: In step (4), the sorghum grains are dried until the moisture content is ≤13%.

Images