Method for regulating and controlling color of tartary buckwheat flavone extracting solution

Abstract

The invention discloses a method for regulating and controlling the color of a tartary buckwheat flavone extracting solution, which comprises the following steps of: monitoring the contents of chlorophyll and proanthocyanidins in the same variety of tartary buckwheat rice which is used for producing the tartary buckwheat flavone extracting solution and has different production places, different varieties or different storage times, and judging whether the tartary buckwheat rice is suitable for being directly used for producing the tartary buckwheat flavone extracting solution; the invention also provides a pretreatment method of the tartary buckwheat rice which is not suitable for being directly used for producing the tartary buckwheat flavone extracting solution; meanwhile, in the production process of the tartary buckwheat flavone extracting solution, white spirit with any flavor of which the pH value is less than 4.0 is selected as a solvent in a redissolving link. On the premise that the contents of total flavonoids and rutin in different batches of produced tartary buckwheat flavone extracting solutions meet the blending requirements of tartary buckwheat wine, the color difference is small, and the blending requirements of the tartary buckwheat wine can be met at the same time.

Description

Technical Field

[0001] This invention relates to the field of quality control of plant raw material extracts, specifically to a method for color regulation of buckwheat flavonoid extract. Background Technology

[0002] Tartary buckwheat rice is the main raw material for the production of tartary buckwheat liquor. One production process involves preparing a flavonoid extract of tartary buckwheat rice at a certain concentration, which is then blended into the liquor. However, when flavonoid extracts of the same variety of tartary buckwheat rice from different origins, different varieties, or with different storage times are used, the color of some batches of the extract differs significantly from that of normal batches, making them unsuitable for direct use in the blending of tartary buckwheat liquor.

[0003] For the quality control of tartary buckwheat rice used in the preparation of tartary buckwheat flavonoid extract, existing technologies mainly refer to national standards such as GB / T 10458-2008, GB / T 5510-2024, and BG 5009.227-2023. Quality control of the tartary buckwheat flavonoid extract primarily involves monitoring the total flavonoid and rutin content. Color control of the extract is currently mainly achieved by adjusting the volume, but this can lead to situations where the color meets production requirements while the total flavonoid and rutin content does not. Therefore, existing quality control measures for tartary buckwheat rice and tartary buckwheat flavonoid extract cannot fully guarantee that the prepared tartary buckwheat flavonoid extract meets the requirements for blending tartary buckwheat liquor in terms of color, total flavonoid, and rutin content. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for color control of buckwheat flavonoid extract, which enables the preparation of buckwheat flavonoid extract using buckwheat rice of the same variety from different origins, varieties, or storage times. The color, total flavonoids, and rutin content of the buckwheat flavonoid extract after volume adjustment all meet production requirements.

[0005] The technical solution provided by this invention is as follows:

[0006] A method for color control of buckwheat flavonoid extract, comprising the following steps:

[0007] (1) Sample and number buckwheat rice from different origins, varieties and processing months. After removing impurities, each numbered buckwheat rice sample is divided into several portions. Randomly select 3-10 portions of buckwheat rice samples to make buckwheat powder. Use a 30-100 mesh steel sieve to sieve the powder. Then weigh 2g-10g of the sieved buckwheat powder and put it into a glass ground glass triangular flask of appropriate volume.

[0008] (2) After adding 20 mL to 50 mL of 50% vol-80% vol ethanol solution to each sample, weigh it and then reflux extract it in a water bath at 65℃-85℃ for ≥30 min.

[0009] (3) After extraction, wait for the extract to cool and weigh it again, and compare it with the weight before extraction. If there is a weight loss, make up the difference with ethanol of the corresponding concentration. After the extract is mixed, filter it and take a sample to test the chlorophyll and proanthocyanidin content in the crude extract.

[0010] (4) The chlorophyll and proanthocyanidin content of the crude extract is used to determine whether buckwheat rice is suitable for direct use in the production of buckwheat flavonoid extract. For buckwheat rice that is not suitable for direct use in the production of buckwheat flavonoid extract, further pretreatment is carried out on the buckwheat rice based on the chlorophyll and proanthocyanidin content before it is used in the production of buckwheat flavonoid extract.

[0011] Preferably, in step (1), the purchased buckwheat rice is first inspected based on the total flavonoid and rutin content to ensure that the total flavonoid and rutin content of the buckwheat rice entering the warehouse meets the production requirements of buckwheat flavonoid extract. The buckwheat rice that passes inspection is stored separately according to its place of origin and variety, and buckwheat rice of the same origin and variety is distinguished and stored in a centralized manner according to the month of harvest and processing.

[0012] Preferably, in step (1), the total flavonoid content of buckwheat rice is determined by aluminum nitrate-sodium nitrite spectrophotometry; the rutin content of buckwheat rice is determined by liquid chromatography; the total flavonoid content of buckwheat rice is required to be ≥1.6%, and the rutin content is required to be ≥1.2%.

[0013] Preferably, in step (1), the buckwheat rice sample is divided into equal portions of 50-500g / portion after impurity removal, more preferably, it is divided into equal portions of 50-250g / portion, and even more preferably, it is divided into equal portions of 100g / portion.

[0014] Preferably, in step (1), five samples of buckwheat rice are randomly selected to make buckwheat powder.

[0015] Preferably, in step (1), the buckwheat flour is ground by a hand-cranked grinder and passes through a 50-mesh steel sieve; or it is crushed by an electric crusher and passes through an 80-100-mesh steel sieve.

[0016] Preferably, the tartary buckwheat flour extracted by reflux in step (2) weighs 2g-10g, and 20mL-500mL of 60% vol ethanol solution is added; more preferably, the tartary buckwheat flour weighs 4g, and 80mL of 50% vol-80% vol ethanol solution is added; even more preferably, the tartary buckwheat flour weighs 5g, and 250mL of 80% vol ethanol solution is added.

[0017] Preferably, the reflux extraction temperature in step (2) is 65°C and the extraction time is 2 hours; or, the reflux extraction temperature is 85°C and the extraction time is 1 hour.

[0018] Preferably, medium-speed qualitative filter paper is used for filtration in step (3); more preferably, 0.8μm fine filter membrane is used for filtration.

[0019] Preferably, in step (3), the chlorophyll content of chlorophyll a and chlorophyll b is detected by spectrophotometry or liquid chromatography; the proanthocyanidin content is detected by spectrophotometry, and more preferably, by iron salt catalysis.

[0020] Preferably, the chlorophyll (a+b) content of a normal batch of tartary buckwheat rice used in the production of tartary buckwheat flavonoid extract is <0.01%.

[0021] If the chlorophyll (a+b) content of buckwheat rice is ≥0.01% in step (4), it is determined that it cannot be directly used for the production of buckwheat flavonoid extract. Buckwheat rice with chlorophyll (a+b) content ≤0.005% should be selected and mixed with it in proportion before the production of buckwheat flavonoid extract is carried out.

[0022] Preferably, the proanthocyanidin content of a normal batch of tartary buckwheat rice used in the production of tartary buckwheat flavonoid extract is <0.08%.

[0023] If the proanthocyanidin content of buckwheat rice is ≥0.08% in step (4), it is determined that it cannot be directly used for the production of buckwheat flavonoid extract. Buckwheat rice needs to be further screened or dehulled to make the proanthocyanidin content of the treated buckwheat rice <0.08% before the production of buckwheat flavonoid extract can be carried out.

[0024] The present invention also provides a method for preparing buckwheat flavonoid extract, which involves pretreating buckwheat rice using the above-mentioned color control method for buckwheat flavonoid extract, followed by solvent extraction, concentration, sedimentation, separation, resolution, and volume adjustment to obtain buckwheat flavonoid extract.

[0025] Preferably, the solvent used in the resolution process is any type of baijiu; more preferably, the baijiu has a pH < 4.0.

[0026] Preferably, the color difference value ΔE of the prepared buckwheat flavonoid extract, compared with pure water, is between 20EBC and 23EBC.

[0027] Preferably, color difference detection is performed using a colorimeter based on the CIE standard colorimetric system.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] By monitoring the chlorophyll and proanthocyanidin content of buckwheat rice from different origins, varieties, and storage times for the production of buckwheat flavonoid extract, the suitability of these rice varieties for direct use in the production of buckwheat flavonoid extract was determined, and a pretreatment method for buckwheat rice unsuitable for direct use was provided. Furthermore, in the production process of buckwheat flavonoid extract, any type of baijiu (Chinese white liquor) with a pH < 4.0 was used as the solvent in the reconstitution stage. Based on this technology, different batches of buckwheat flavonoid extract produced exhibited minimal color differences, provided that the total flavonoid and rutin content met the blending requirements for buckwheat liquor, thus simultaneously satisfying the blending requirements for buckwheat liquor. Detailed Implementation

[0030] The present application will be further explained below with reference to specific embodiments, but the embodiments do not limit the present application in any way.

[0031] Example 1

[0032] A batch of buckwheat rice, from the same origin and of the same variety, passed factory inspection, which showed that the total flavonoids and rutin levels met the acceptance requirements. Upon arrival at the warehouse, the buckwheat rice was inventoried and stacked bag by bag according to the processing time, covering five processing months. Samples were taken and numbered according to the processing month, designated 1-5. Samples 1-5 underwent impurity removal treatment, and each sample was packaged in 200g portions. Five portions of each package were randomly selected for buckwheat flour preparation and numbered 1-1 to 1-5…, 5-1 to 5-5. Buckwheat flour was prepared using a hand-cranked grinder and sieved through a 50-mesh steel sieve. 4g of each portion of the 50-mesh sieve-passed buckwheat flour was weighed and placed into 250mL glass Erlenmeyer flasks with ground glass stoppers. 80mL of 60% vol ethanol was added, and the flasks were weighed and then refluxed in a water bath at 85℃ for 1 hour. After extraction, the extract was allowed to return to room temperature before weighing. For samples with weight loss, the weight was replenished with 60% vol ethanol. After shaking well, the extract was filtered through a 0.8 μm fine filter membrane. The chlorophyll and proanthocyanidin contents in the filtered crude extract were detected spectrophotometrically. The results are shown in Table 1.

[0033] Table 1. Average chlorophyll and proanthocyanidin content in crude buckwheat extracts at different processing times.

[0034] Sample number No. 1 No. 2 No. 3 No. 4 No. 5 Chlorophyll (a+b) 0.004％ 0.003％ 0.005％ 0.004％ 0.003％ Proanthocyanidins 0.060％ 0.042％ 0.056％ 0.095％ 0.055％

[0035] According to the test results, the average proanthocyanidin content of the buckwheat rice in sample No. 4 did not meet the production requirements for buckwheat flavonoid extract. The buckwheat rice was further sieved using a vibrating sieve to remove some unhulled rice. The crude extract extraction and proanthocyanidin testing were then repeated. Through further sieving, the average proanthocyanidin content in the buckwheat rice in sample No. 4 decreased to 0.045%, meeting the production requirements for buckwheat flavonoid extract.

[0036] The production of buckwheat concentrate is carried out in batches, with each batch consisting of one feeding. A total of four batches of buckwheat concentrate were produced from this batch of buckwheat rice. During the production of the four batches of buckwheat concentrate, the same batch of compound-flavored liquor was used for reconstitution, with a pH of 3.79. After volume adjustment, the color difference of the buckwheat flavonoid extract was measured using a colorimeter based on the CIE standard colorimetric system. The color difference values ​​of each batch of buckwheat flavonoid extract were all between 20EBC and 23EBC, which meets the requirements for blending buckwheat liquor.

[0037] Example 2

[0038] A batch of buckwheat rice, originating from the same region, comprised three varieties, designated A, B, and C. Upon arrival at the factory, inspection revealed that the total flavonoid and rutin content of all three varieties met acceptance requirements. During storage, each variety was stored in a separate area, stacked according to processing time. Varieties A and B were processed within the past month. Samples of varieties A and B were taken separately and packaged in 100g bags. Random sampling was performed on each package, resulting in three samples from each variety for buckwheat powder preparation, which were then numbered A-1 to A-3 and B-1 to B-3. Variety C buckwheat rice spanned two processing months. Samples from different processing months were taken and packaged in 100g bags. Random sampling was performed on each package, resulting in three samples from each variety for buckwheat powder preparation, which were then numbered C1-1 to C1-3 and C2-1 to C2-3. Buckwheat flour was prepared using an electric crusher and sieved through an 80-mesh steel sieve. 2g of each of the 80-mesh sieve-passed buckwheat flour samples were weighed and placed into separate 250mL glass Erlenmeyer flasks with ground glass stoppers. 100mL of 50% vol ethanol was added, and the samples were weighed and then placed in a water bath for reflux extraction at 65℃ for 2 hours. After extraction, the extract was allowed to return to room temperature before weighing. For samples with weight loss, 50% vol ethanol was used to replenish the weight. The extract was then filtered through medium-speed qualitative filter paper. The chlorophyll content in the filtered crude extract was determined by liquid chromatography, and the proanthocyanidin content was determined by ultraviolet spectrophotometry. The results are shown in Table 2.

[0039] Table 2. Average chlorophyll and proanthocyanidin content in crude extracts of different varieties of buckwheat.

[0040] Sample number Tartary Buckwheat A Buckwheat B Buckwheat C1 Buckwheat C2 Chlorophyll (a+b) 0.008％ 0.003％ 0.011％ 0.011％ Proanthocyanidins 0.060％ 0.042％ 0.056％ 0.065％

[0041] The test results showed that the chlorophyll (a+b) content of variety C buckwheat rice was too high, which did not meet the production requirements for buckwheat flavonoid extract. Variety B buckwheat rice had a chlorophyll (a+b) content of <0.005%. Variety B and variety C were mixed in a 1:1 ratio, and the crude extract extraction and chlorophyll testing were repeated. The chlorophyll content of the mixed buckwheat rice was found to be 0.008%, which met the production requirements for buckwheat flavonoid extract.

[0042] This batch of buckwheat rice was used to produce two batches of buckwheat concentrate. During the reconstitution process, the first batch used a light-aroma baijiu (Chinese liquor) with a pH of 3.92, while the second batch used a sauce-aroma baijiu with a pH of 3.55. After volume adjustment, the color difference of the two batches of buckwheat flavonoid extract was measured using a colorimeter based on the CIE standard colorimetric system. The color difference values ​​were both between 20 EBC and 23 EBC, meeting the requirements for buckwheat liquor blending.

[0043] Example 3

[0044] Two batches of buckwheat rice, from different origins and of different varieties, were identified as A and B. Upon arrival at the factory, inspection revealed that the total flavonoid and rutin content of both varieties met the acceptance requirements. The buckwheat rice was stored in separate areas for each variety, stacked according to processing time. Variety A included two processing months, and variety B included three processing months. Samples of each variety were taken from different processing months and packaged in 250g bags. Random sampling was performed on the packaged samples, and 10 samples from each variety were randomly selected for buckwheat flour preparation and numbered. Variety A samples were numbered A1-1 to A1-10, A2-1 to A2-10; variety B samples were numbered B1-1 to B1-10, B2-1 to B2-10, and B3-1 to B3-10. Buckwheat flour preparation used an electric crusher and was sieved through a 100-mesh steel sieve. Weigh 5g of each of the tartary buckwheat flours that have passed through a 100-mesh sieve, and place them separately into 500mL glass Erlenmeyer flasks with ground glass stoppers. Add 200mL of 80% vol ethanol, weigh, and then place in a water bath. Reflux extraction at 75℃ for 1.5h. After extraction, allow the extract to return to room temperature and weigh again. For samples with weight loss, replenish the weight with 80% vol ethanol. Shake well and filter the extract using medium-speed qualitative filter paper. The chlorophyll content in the filtered crude extract was determined by liquid chromatography, and the proanthocyanidin content was determined by ultraviolet spectrophotometry. The results are shown in Table 3.

[0045] Table 3. Average chlorophyll and proanthocyanidin content in crude extracts of different varieties and origins of tartary buckwheat.

[0046]

[0047]

[0048] According to the test results, the chlorophyll (a+b) content in samples of variety A buckwheat rice from both processing months was too high, failing to meet the production requirements for buckwheat flavonoid extract. The chlorophyll (a+b) content of samples B2 and B3 was <0.005%, allowing them to be mixed with variety A buckwheat rice. However, the proanthocyanidin content in buckwheat rice from processing dates B1 and B2 was too high, also failing to meet the production requirements for buckwheat flavonoid extract. The amount of B3 was insufficient for mixing with variety A. First, B1 and B2 were sieved again using a vibrating sieve to remove some unhulled buckwheat rice. Samples were then taken and the crude extract extraction and proanthocyanidin testing procedures were repeated. Through further sieving, the average proanthocyanidin content in B1 and B2 buckwheat rice decreased to 0.055% and 0.062%, respectively, meeting the production requirements for buckwheat flavonoid extract. B2 and B3 were then mixed with variety A buckwheat rice in a 7:3 ratio, and samples were taken again to repeat the crude extract extraction and chlorophyll (a+b) testing procedures. The chlorophyll content of the mixed buckwheat rice was found to be 0.006%, which meets the production requirements for buckwheat flavonoid extract.

[0049] The two batches of buckwheat rice were used to produce three batches of buckwheat concentrate. During the production of the three batches of buckwheat concentrate, the first batch used light-aroma baijiu (pH 3.92), the second batch used sauce-aroma baijiu (pH 3.55), and the third batch used strong-aroma baijiu (pH 3.77). After volume adjustment, the color difference of the three batches of buckwheat flavonoid extract was measured using a colorimeter based on the CIE standard colorimetric system. The color difference values ​​were all between 20 EBC and 23 EBC, which meets the requirements for blending buckwheat liquor.

[0050] In summary, this application's embodiments monitor the chlorophyll and proanthocyanidin content in buckwheat rice of the same variety from different origins, with different varieties, or stored for different times for the production of buckwheat flavonoid extract. Targeted pretreatment is performed on buckwheat rice unsuitable for direct use in buckwheat flavonoid extract production. Furthermore, during the reconstitution stage of buckwheat flavonoid extract production, any type of baijiu with a pH < 4.0 is used. Based on this technology, different batches of buckwheat flavonoid extract produced, provided that the total flavonoid and rutin content meet the requirements for buckwheat liquor blending, exhibit minimal color differences, thus simultaneously satisfying the blending requirements for buckwheat liquor.

[0051] Obviously, the embodiments listed in this application are merely examples to more clearly illustrate the present invention, and are not intended to limit the implementation of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for color control of buckwheat flavonoid extract, characterized in that, Includes the following steps: (1) Sample and number buckwheat rice from different origins, varieties and processing months. After removing impurities, each numbered buckwheat rice sample is divided into several portions. Randomly select 3-10 portions of buckwheat rice samples to make buckwheat powder. Use a 30-100 mesh steel sieve to sieve the powder. Then weigh 2g-10g of the sieved buckwheat powder and put it into a glass ground glass triangular flask of appropriate volume. (2) After adding 20 mL to 50 mL of 50% vol-80% vol ethanol solution to each sample, weigh it and then reflux extract it in a water bath at 65℃-85℃ for ≥30 min. (3) After extraction, wait for the extract to cool and weigh it again, and compare it with the weight before extraction. If there is a weight loss, make up the difference with ethanol of the corresponding concentration. After the extract is mixed, filter it and take a sample to test the chlorophyll and proanthocyanidin content in the crude extract. (4) The chlorophyll and proanthocyanidin content of the crude extract is used to determine whether buckwheat rice is suitable for direct use in the production of buckwheat flavonoid extract. For buckwheat rice that is not suitable for direct use in the production of buckwheat flavonoid extract, further pretreatment is carried out on the buckwheat rice based on the chlorophyll and proanthocyanidin content before it is used in the production of buckwheat flavonoid extract.

2. The method for color control of buckwheat flavonoid extract according to claim 1, characterized in that, In step (1), after removing impurities, the buckwheat rice sample is divided into equal portions of 50-500g / portion, more preferably, into equal portions of 50-250g / portion, and even more preferably, into equal portions of 100g / portion.

3. The method for color control of buckwheat flavonoid extract according to claim 1, characterized in that, In step (2), the weight of the tartary buckwheat powder extracted by reflux is 2g-10g, and 20mL-500mL of 60% vol ethanol solution is added; more preferably, the weight of the tartary buckwheat powder is 4g, and 80mL of 50% vol-80% vol ethanol solution is added; more preferably, the weight of the tartary buckwheat powder is 5g, and 250mL of 80% vol ethanol solution is added.

4. The method for color control of buckwheat flavonoid extract according to claim 1, characterized in that, In step (2), the reflux extraction temperature is 65℃ and the extraction time is 2h; or, the reflux extraction temperature is 85℃ and the extraction time is 1h.

5. The method for color control of buckwheat flavonoid extract according to claim 1, characterized in that, In step (3), medium-speed qualitative filter paper is used for filtration; more preferably, 0.8μm fine filter membrane is used for filtration; chlorophyll content of chlorophyll a and chlorophyll b is detected by spectrophotometry or liquid chromatography; proanthocyanidin is detected by spectrophotometry, and more preferably by iron salt catalysis.

6. The method for color control of buckwheat flavonoid extract according to claim 1, characterized in that, In step (4), the chlorophyll (a+b) content of the normal batch of buckwheat rice used for the production of buckwheat flavonoid extract is <0.01%. If the chlorophyll (a+b) content of buckwheat rice is ≥0.01%, it is determined that it cannot be directly used for the production of buckwheat flavonoid extract. It is necessary to select buckwheat rice with chlorophyll (a+b) content ≤0.005% and mix it with the chlorophyll (a+b) content in a certain proportion before the production of buckwheat flavonoid extract. The normal batch of tartary buckwheat rice used for the production of tartary buckwheat flavonoid extract has a proanthocyanidin content of <0.08%. If the proanthocyanidin content of tartary buckwheat rice is ≥0.08%, it is determined that it cannot be used directly for the production of tartary buckwheat flavonoid extract. The tartary buckwheat rice needs to undergo further screening or dehulling to ensure that the proanthocyanidin content of the treated tartary buckwheat rice is <0.08% before it can be used for the production of tartary buckwheat flavonoid extract.

7. A method for preparing a flavonoid extract from tartary buckwheat, characterized in that, After pretreatment of tartary buckwheat rice using the color control method described in any one of claims 1-6, tartary buckwheat flavonoid extract is obtained by solvent extraction, concentration, sedimentation, separation, resolution, and volume adjustment.

8. The method according to claim 7, characterized in that, The solvent used in the redissolution process can be any type of baijiu; more preferably, the baijiu has a pH < 4.

0.

9. The method according to claim 7, characterized in that, The color difference ΔE between the prepared buckwheat flavonoid extract and pure water was between 20EBC and 23EBC.

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