Method and model for identifying storage quality of sorghum for brewing

Abstract

The present application belongs to the technical field of grain storage, and particularly relates to a method and model for identifying the storage quality of distilling sorghum. In order to scientifically, objectively and effectively identify the storage quality of distilling sorghum, the present application provides a method for identifying the storage quality of distilling sorghum, which is to determine the fatty acid value and protein concentration in the sorghum sample, and draw a scatter plot by taking the fatty acid value and protein concentration as the horizontal and vertical coordinates respectively, to obtain a model for identifying the storage quality of distilling sorghum, and determine the quality of the sorghum sample according to the numerical distribution trend in the model. In the model, when the fatty acid value of the distilling sorghum is less than or equal to 30 μmol / g, and the protein concentration is greater than or equal to 2 mg / g, it is determined that the quality of the sorghum sample is normal, otherwise it is determined that the quality of the sorghum sample is abnormal. Experiments prove that the present application takes the fatty acid value and protein concentration of the distilling sorghum as the judgment parameters, can effectively determine whether the quality of the distilling sorghum is normal, and can effectively eliminate the influence of unstable quality of the sorghum caused by the experience and subjectivity of artificial grain inspection, thereby improving the quality of the liquor.

Description

Technical Field

[0001] This invention belongs to the field of grain storage technology, specifically relating to a method and model for identifying the storage quality of brewing sorghum. Background Technology

[0002] Sorghum is a crucial raw material for baijiu (Chinese liquor) brewing. Various types of baijiu, including sauce-aroma, strong-aroma, light-aroma, phoenix-aroma, and soy-sauce-aroma baijiu, all use sorghum as their primary brewing ingredient. Color and aroma are important quality indicators for brewing sorghum. Abnormal sorghum odors are mainly caused by improper storage. Common off-odors in sorghum include off-flavors, sourness, medicinal taste, moldiness, and rancidity. Using sorghum with abnormal odors will result in two problems: first, these off-flavors will transfer to the liquor during fermentation and distillation, leading to impurities and affecting the taste and aroma; second, sorghum with abnormal odors may carry unwanted microorganisms that can interfere with fermentation, resulting in a lower yield. Therefore, baijiu companies have high requirements for the storage quality of sorghum, and sorghum with abnormal odors cannot be used in brewing production.

[0003] Currently, there is no national standard for judging the storage quality of sorghum for brewing that can be used as a reference by liquor companies. The sorghum quality judgment method specified in DB15 / T 376-2024 "Rules for Judging the Storage Quality of Miscellaneous Grains" is not applicable to some liquor companies. First, the fatty acid value determination method is difficult to apply to actual production. The seed coat of brewing sorghum is mostly reddish-brown, so the extract is also reddish-brown, making it difficult to accurately determine the titration endpoint during fatty acid value determination. Therefore, although this judgment method is applicable to other grains, such as rice, it is not applicable to sorghum. Second, the sorghum storage quality indicators are not applicable to brewing companies. The main method used by liquor producers to judge the storage quality of sorghum is the olfactory method, which relies on human senses and is greatly affected by the olfactory sensitivity, experience, and subjective factors of grain inspectors. Therefore, establishing a scientific, objective, and effective method for identifying the storage quality of brewing sorghum and using it for quality monitoring is of great significance for improving the raw material testing level of liquor producers and ensuring the safety of raw material quality. Summary of the Invention

[0004] In order to establish a scientific, objective and effective method for identifying the storage quality of sorghum for brewing and to use it for quality monitoring, this invention provides a method and model for identifying the storage quality of sorghum for brewing.

[0005] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: In a first aspect, the present invention provides a method for identifying the storage quality of brewing sorghum, comprising the following steps: The fatty acid value and protein concentration in sorghum samples were measured, and a scatter plot was drawn with fatty acid value and protein concentration as variables to obtain a sorghum storage quality identification model for brewing. The quality of sorghum samples was determined based on the model.

[0006] Furthermore, when the fatty acid value of the brewing sorghum is ≤30 μmol / g and the protein concentration is ≥2 mg / g, the sorghum sample is judged to be of normal quality; otherwise, it is judged to be abnormal.

[0007] Furthermore, the method for determining fatty acid value includes the following steps: weighing a sorghum sample, adding n-hexane, centrifuging, and taking the supernatant; then adding a mixed solution of n-heptane, methanol, and chloroform and copper reagent, centrifuging, taking the supernatant, adding a colorimetric reagent, and measuring the absorbance at 550 nm to obtain the fatty acid value.

[0008] Preferably, the ratio of sorghum sample to n-hexane liquid is 0.1:1 to 0.2:1 g / mL.

[0009] Preferably, the centrifugation conditions are 5000-8000 rpm for 5-10 min.

[0010] Preferably, the volume ratio of n-heptane:methanol:chloroform in the mixed solution of n-heptane, methanol, and chloroform is 24:1:25.

[0011] Preferably, the supernatant is a mixed solution of n-heptane, methanol, and chloroform, with a copper reagent volume ratio of 1:10:4 to 1:12:5.

[0012] Preferably, the copper reagent is an aqueous solution containing 3-5% copper acetate and 2-3% pyridine.

[0013] Preferably, the volume ratio of the supernatant to the colorimetric reagent is 1:4 to 1:2.

[0014] Preferably, the colorimetric agent is a methanol solution containing 0.4-0.5% diphenylcarbazine and 0.01-0.03% diphenylcarbazine.

[0015] Furthermore, the protein concentration determination method includes the following steps: centrifuging and lysing the sorghum sample using buffer I to obtain the supernatant, adding the dye solution, and measuring the absorbance at 595 nm to obtain the protein concentration.

[0016] Preferably, the centrifugation conditions are 10,000–12,000 rpm for 5–10 min.

[0017] Preferably, the ratio of sorghum sample to buffer I is 1:6 to 1:8 g / mL.

[0018] Preferably, buffer I consists of: 50 mL of 1M Tris-HCl at pH 7.5, 30 mL of 5M NaCl, 10 mL of 1 M MgCl2·6H2O, 2 mL of 0.5 M EDTA, 1 mL of IGEPAL® CA-630, and ddH2O to a final volume of 1 L.

[0019] Secondly, the present invention provides a storage quality identification model for brewing sorghum established in the above identification method. In the model, the area of ​​brewing sorghum with fatty acid value ≤30 μmol / g and protein concentration ≥2 mg / g is the normal quality area of ​​sorghum, and the rest is the abnormal category.

[0020] Beneficial Effects: This invention provides a method for identifying the storage quality of sorghum for brewing. It involves measuring the fatty acid value and protein concentration in sorghum samples, plotting a scatter plot with fatty acid value and protein concentration as the x and y axes respectively, to obtain a model for identifying the storage quality of sorghum for brewing. The quality of the sorghum sample is determined based on the numerical distribution trend in the model. When the fatty acid value of the brewing sorghum is ≤30 μmol / g and the protein concentration is ≥2 mg / g, the sorghum sample is considered to be of normal quality; otherwise, it is considered abnormal. Experiments have confirmed that this invention, using fatty acid value and protein concentration as judgment parameters, can effectively determine whether the quality of brewing sorghum is normal, effectively eliminating the influence of experience and subjectivity on the unstable quality of sorghum caused by manual grain inspection, thereby improving the quality of liquor. Attached Figure Description

[0021] Figure 1 This is a diagram of the sorghum for brewing prepared in Example 1 of the present invention, used for identifying the storage quality. Detailed Implementation

[0022] To make the technical problems, solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with the embodiments. Unless otherwise defined, all technical terms used herein have the same meaning as understood by one of ordinary skill in the art.

[0023] In one embodiment of the present invention, by measuring the fatty acid value and protein concentration in sorghum samples, and plotting a scatter plot with the fatty acid value and protein concentration as the horizontal and vertical axes respectively, a sorghum storage quality identification model for brewing is obtained. The quality of the sorghum sample is determined based on the numerical distribution trend in the model. However, existing literature has not yet found any use of fatty acid value and protein concentration as parameters for sorghum quality identification.

[0024] In one specific embodiment of the present invention, when the fatty acid value of the brewing sorghum is ≤30 μmol / g and the protein concentration is ≥2 mg / g, the sorghum sample is judged to be of normal quality; otherwise, it is judged to be abnormal.

[0025] In a specific embodiment of the present invention, the method for determining fatty acid value includes the following steps: weighing a sorghum sample, adding n-hexane, centrifuging, and taking the supernatant; then adding a mixed solution of n-heptane, methanol, and chloroform and copper reagent, centrifuging, taking the supernatant, adding a colorimetric reagent, and measuring the absorbance at 550 nm to obtain the fatty acid value.

[0026] Compared to the titration method used in DB15 / T 376-2024 "Rules for Judging the Storage Quality of Miscellaneous Grains" to determine fatty acid values, the titration endpoint is not obvious due to the reddish color of sorghum, leading to errors in fatty acid value determination. This invention uses the absorbance method to determine fatty acid values, employing the colorimetric reagents diphenylcarbazide and diphenylcarbazide hydrazone, which allows for more accurate determination of fatty acid values ​​and is more beneficial for sorghum quality identification.

[0027] The following specific embodiments will be provided to explain the solution of the present invention. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0028] The copper reagent used in the following examples was prepared by weighing 1.25 g of copper acetate, adding 0.75 mL of pyridine and 24.25 mL of water, and mixing well.

[0029] The colorimetric reagent used in the following examples was obtained by weighing 0.475 g of diphenylcarbazine and 0.025 g of diphenylcarbazine, mixing them, and dissolving them in 100 mL of anhydrous methanol.

[0030] The buffer I used in the following examples consisted of: 50 mL of 1 M Tris-HCl (pH 7.5), 30 mL of 5 M NaCl, 10 mL of 1 M MgCl2·6H2O, 2 mL of 0.5 M EDTA, 1 mL of IGEPAL® CA-630, and ddH2O to a final volume of 1 L.

[0031] The IGEPEAL® CA-630 was purchased from Merck KGaA in Darmstadt, Germany, and its model number is I3021.

[0032] The Coomassie Brilliant Blue assay (Bradford assay) kit used in the following examples was purchased from Shanghai Beyotime Biotechnology Co., Ltd., model number P0006C.

[0033] Example 1 Five grain inspectors distinguished 315 samples of brewing sorghum, collecting 154 samples of normal quality and 161 samples of abnormal quality. The following methods were used to determine the fatty acid value and protein concentration of the two types of brewing sorghum.

[0034] Methods for determining fatty acid value and protein concentration in sorghum: (1) Weigh 0.1044 g of sorghum sample, add 1 mL of n-hexane, shake well, centrifuge at 8000 rpm for 5 min at 4℃, take 50 μL of supernatant, add 500 μL of a mixed solution of n-heptane, methanol and chloroform (n-heptane:methanol:chloroform volume = 24:1:25) and 200 μL of copper reagent, shake well for 5 min, centrifuge at 5000 rpm for 10 min at 4℃. Take 200 μL of the supernatant after centrifugation, add 800 μL of colorimetric reagent, shake for 3 min, and measure the absorbance at 550 nm to obtain the fatty acid value.

[0035] (2) Weigh 0.0500 g of sorghum sample, add 300 μL of buffer I, shake to mix, centrifuge at 12000 rpm for 7 min at 4℃, transfer the supernatant to a new set of centrifuge tubes, repeat centrifugation at 12000 rpm for 7 min, transfer 10 μL of supernatant, and use the Coomassie Brilliant Blue (Bradford method) kit to determine the protein concentration of sorghum. Prepare protein standards of different concentrations: add 300 μL of Coomassie Brilliant Blue (G-250) staining solution to the supernatant, mix well, let stand for 5 minutes, and measure the absorbance at 595 nm to obtain the protein concentration.

[0036] In Excel, a scatter plot was created with fatty acid values ​​of 315 sorghum samples on the x-axis and protein concentration on the y-axis, and the plot was structured as follows: Figure 1 The model shown is for identifying the storage quality of sorghum used for brewing. After multiple tests, it was found that the discrimination region for sorghum of normal quality is fatty acid value ≤30 μmol / g and protein concentration ≥2 mg / g.

[0037] Experimental Example 1 Sorghum sample #1 was taken and, according to the grain inspector's assessment and the DB15 / T 376-2024 "Rules for Judging the Storage Quality of Miscellaneous Grains" standard, was determined to be of normal quality. Fatty acid value and protein concentration were determined according to the method in Example 1. The fatty acid value of sorghum sample #1 was 6.19 μmol / g, and the protein concentration was 4.46 mg / g. This falls within the range of fatty acid value ≤30 μmol / g and protein concentration ≥2 mg / g, thus classifying it as normal quality sorghum, consistent with the results obtained by the grain inspector and the DB15 / T 376-2024 standard.

[0038] Experimental Example 2 Sorghum sample #2 was taken and, according to the grain inspector's assessment and the DB15 / T 376-2024 "Rules for Judging the Storage Quality of Miscellaneous Grains" standard, was determined to be of abnormal quality. Following the method in Example 1, fatty acid value and protein concentration were measured. The fatty acid value of sorghum sample #2 was 57.72 μmol / g, and the protein concentration was 0.31 mg / g. This does not fall within the range of fatty acid value ≤30 μmol / g and protein concentration ≥2 mg / g, therefore it was determined to be of abnormal quality, consistent with the results measured by the grain inspector and the DB15 / T 376-2024 standard.

Claims

1. A method for identifying the storage quality of sorghum used for brewing, characterized by: Includes the following steps: The fatty acid value and protein concentration in sorghum samples were measured, and a scatter plot was drawn with fatty acid value and protein concentration as variables to obtain a sorghum storage quality identification model for brewing. The quality of sorghum samples was determined based on the model.

2. The method for identifying the storage quality of brewing sorghum according to claim 1, characterized in that: When the fatty acid value of the sorghum used for brewing is ≤30 μmol / g and the protein concentration is ≥2 mg / g, the sorghum sample is considered to be of normal quality; otherwise, it is considered to be abnormal.

3. The method for identifying the storage quality of brewing sorghum according to claim 1 or 2, characterized in that: The method for determining fatty acid value includes the following steps: weigh a sorghum sample, add n-hexane, centrifuge, and take the supernatant; then add a mixed solution of n-heptane, methanol, and chloroform and copper reagent, centrifuge, take the supernatant, add a colorimetric reagent, and measure the absorbance at 550 nm to obtain the fatty acid value.

4. The method for identifying the storage quality of brewing sorghum according to claim 3, characterized in that: Meet at least one of the following: The ratio of sorghum sample to n-hexane liquid was 0.1:1 to 0.2:1 g / mL; Centrifugation conditions: 5000–8000 rpm for 5–10 min; In a mixed solution of n-heptane, methanol, and chloroform, the volume ratio of n-heptane:methanol:chloroform is 24:1:

25. The volume ratio of the supernatant, n-heptane, methanol, and chloroform to the copper reagent is 1:10:4 to 1:12:

5. The copper reagent is an aqueous solution containing 3-5% copper acetate and 2-3% pyridine.

5. The method for identifying the storage quality of brewing sorghum according to claim 4, characterized in that: The volume ratio of the supernatant to the colorimetric reagent is 1:4 to 1:

2.

6. The method for identifying the storage quality of brewing sorghum according to claim 5, characterized in that: The colorimetric reagent is a methanol solution containing 0.4–0.5% diphenylcarbazine and 0.01–0.03% diphenylcarbazine.

7. The method for identifying the storage quality of brewing sorghum according to claim 1 or 2, characterized in that: The protein concentration determination method includes the following steps: centrifuging and lysing the sorghum sample using buffer I to obtain the supernatant, adding the dye solution, and measuring the absorbance at 595 nm to obtain the protein concentration.

8. The method for identifying the storage quality of brewing sorghum according to claim 7, characterized in that, Meet at least one of the following: Centrifugation conditions: 10000–12000 rpm for 5–10 min; The ratio of sorghum sample to buffer I was 1:6 to 1:8 g / mL; The buffer I consists of: 50 mL of 1M Tris-HCl at pH 7.5, 30 mL of 5M NaCl, 10 mL of 1M MgCl2·6H2O, 2 mL of 0.5M EDTA, 1 mL of IGEPAL® CA-630, and ddH2O to a final volume of 1 L.

9. The sorghum storage quality identification model established in the sorghum storage quality identification method according to any one of claims 1 to 8.

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