Method for optimizing shiny-leaved yellowhorn tea extraction process

Abstract

The invention provides a method for optimizing a shiny-leaved yellowhorn tea extraction process. Comprising the following steps: adopting a single factor test in combination with a response surface analysis method, selecting methanol concentration, liquid-material ratio and extraction time as investigation factors, taking total flavone and tea polyphenol content and extract yield as comprehensive indexes, and carrying out a verification test to finally obtain optimal process parameters; the optimal process parameters obtained by the method are as follows: the methanol concentration is 60%, the liquid-material ratio is 40: 1mL / g, and the extraction time is 35min. A verification test is repeated for three times according to the improved optimal process condition, the actual comprehensive score of the obtained shiny-leaved yellowhorn tea extraction process is 0.7033 and is close to a theoretical value 0.7130, the relative error is only 1.36%, and it is indicated that the method for extracting the process parameters through the model with the optimized response surface is quite accurate and reliable.

Description

Technical Field

[0001] The invention relates to the field of Xanthoceras sorbifolia tea leaf extraction technology, and in particular to a method for optimizing the Xanthoceras sorbifolia tea leaf extraction technology. Background Art

[0002] The Mongolian medicine Xanthoceras sorbifolium Bunge is a plant of the genus Xanthoceras in the Sapindaceae family. It is a deciduous shrub or small tree with the characteristics of slightly bitter, slightly sweet and cool in nature.

[0003] Xanthoceras sorbifolia is a plant with both medicinal and edible properties. Domestic and foreign researchers have studied the chemical components of various parts of Xanthoceras sorbifolia. The main phytochemical components of different parts of Xanthoceras sorbifolia include triterpenes, flavonoids, phenolic acids, coumarins, lignans, hemiterpenes, monoterpenes, alkaloids and sterols. Among them, triterpenes, flavonoids and phenolic acids are the main compounds. Triterpenes are one of the main components of Xanthoceras sorbifolia. So far, triterpenoid compounds have been reported from Xanthoceras sorbifolia, and their main chains are mainly composed of lupine type, gansuline type, scutellaria type, cycloartane type, lanolin type, etc.; many flavonoid compounds have been isolated and identified from Xanthoceras sorbifolia. So far, statistical data show that the main types are brass, flavanone, dihydroflavonoid, biflavonoid and other compounds; phenolic acids are widely distributed in Xanthoceras sorbifolia as bioactive substances. The phenolic compounds isolated from Xanthoceras sorbifolia are protocatechuic acid, ethyl protocatechuic acid, vanillic acid, p-hydroxybenzaldehyde, 3,4,5-trimethoxybenzoic acid, p-hydroxyphenylacetic acid, 2-hydroxy-6-methylbenzoic acid, tyrosol and p-hydroxymethylbenzoic acid vanillic acid.

[0004] To date, many studies have revealed the pharmacological effects of Xanthoceras sorbifolia. The active ingredients extracted from Xanthoceras sorbifolia have various pharmacological properties, including antioxidant, antibacterial, antitumor, anti-neuroinflammatory, anti-adipogenic, anti-obesity, anticoagulant, anti-HIV, gastroprotective, immunomodulatory and anti-inflammatory properties.

[0005] However, how to obtain the optimal process parameters for the extraction of Xanthoceras sorbifolia tea leaves has not been reported. Summary of the invention

[0006] The purpose of the invention is to provide a method for optimizing the extraction process of Xanthoceras sorbifolia tea leaves.

[0007] The present invention is achieved through the following technical solutions:

[0008] The invention relates to a method for optimizing an extraction process of Xanthoceras sorbifolia tea leaves. The method comprises the following steps: adopting a single factor experiment combined with a response surface analysis method, selecting methanol concentration, liquid-to-solid ratio and extraction time as investigation factors, taking total flavonoids, tea polyphenols content and extract yield as comprehensive indicators, and conducting a verification experiment to finally obtain optimal process parameters.

[0009] Preferably, the method comprises the following specific steps:

[0010] Step 1, preparation of Xanthoceras sorbifolia tea leaves;

[0011] Step 2, determination of the content of total flavonoids and tea polyphenols in Xanthoceras sorbifolia tea leaves and the yield of extract;

[0012] Step 3, single factor test;

[0013] Step 4: Box-Behnken response surface screening of extraction process parameters.

[0014] Preferably, in step 1, the Xanthoceras sorbifolia tea preparation process flow is: picking → cleaning → draining → spreading fresh leaves → withering → rolling → frying → drying → finished product.

[0015] Preferably, in step 1, the picking selects the tender leaves at the top of one year old, and cleans them after picking; the greening is the core process of tea making, the greening temperature is 100-120℃, the greening time is 2-3min, and the greening needs to be killed quickly at high temperature to achieve the purpose of completely passivating the activity of oxidase, because the water in the leaves evaporates a lot during greening, making the leaves soft, exuding the original fragrance of Xanthoceras sorbifolia leaves, and the leaves are not easy to loosen by hand; the rolling time is 3-8min, so that the leaves are rolled into ropes, the leaf cells are broken to squeeze out the juice, and the green leaves are fried while hot after the pot is removed from the pot; the greening time is 3-5min, the pot temperature during greening is 240-260℃, and the speed of stir-frying is flexibly controlled according to the degree of heat of the leaves. After drying a little, the second greening is carried out, and the temperature of the drying pot is 200-240℃. When it is hot to the touch, it is taken out of the pot, dried and shaped to obtain the finished product.

[0016] Preferably, in step 2, the specific steps of determining the total flavonoids, tea polyphenols content and extract yield in the Xanthoceras sorbifolia tea leaves are:

[0017] Step 2.1, drying the prepared Xanthoceras sorbifolia tea leaves, crushing them, and passing them through an 80-mesh sieve for later use;

[0018] Step 2.2, determination of total flavonoid content: NaNO2-Al(NO3)3-NaOH colorimetric method was used, rutin was used as reference, and a linear equation was drawn: Y = 0.0467X - 0.0052 (R 2 =0.9996);

[0019] Step 2.3, determination of tea polyphenols content: according to GB / T8313-2018 detection method for tea polyphenols in tea leaves;

[0020] Step 2.4, determination of extract yield: quantitatively measure the methanol extract of Xanthoceras sorbifolia tea leaves, place it in an evaporating dish that has been dried to constant weight, evaporate it in a water bath, place it in a drying oven at 105°C to constant weight, take it out and cool it in a desiccator for 30 minutes, accurately weigh the mass, and calculate the extract yield.

[0021] Preferably, in step 3, the specific steps of the single factor test are as follows:

[0022] Step 3.1, determination of comprehensive scoring weight coefficient:

[0023] Label each component: Comprehensively score the components with total flavonoids, tea polyphenols content and extract yield as indicators. Since total flavonoids are the main antioxidant active component of Xanthoceras sorbifolia tea, it is recorded as 50%, tea polyphenols are relatively minor active ingredients, and it is recorded as 35%. The dry extract yield is marked as 15% as an auxiliary inspection indicator.

[0024] It can be calculated according to the comprehensive scoring formula, which is as follows: Comprehensive score = flavonoid content in each sample / the highest flavonoid content in the group of samples × 50% + tea polyphenol content in each sample / the highest tea polyphenol content in the group of samples × 35% + extract yield in each sample / the highest extract yield in the group of samples × 15%;

[0025] Step 3.2, Effect of methanol concentration:

[0026] Accurately weigh 6 portions of Xanthoceras sorbifolia tea powder in a triangular flask, 0.5 g each, and add 40 times the volume fraction of 0%, 20%, 40%, 60%, 80%, and 100% methanol, respectively. After ultrasonic extraction at 30°C for 30 minutes, supplement the reduced mass with the same volume fraction of methanol solution and filter to obtain the Xanthoceras sorbifolia tea alcohol extract; the methanol concentrations of 20%, 40%, and 60% were obtained as the optimized experimental conditions;

[0027] Step 3.3, influence of liquid-to-solid ratio:

[0028] Weigh 6 portions of Xanthoceras sorbifolia tea powder accurately into a triangular flask, 0.5 g each, add 20, 40, 60, 80, 100, and 120 times the volume fraction of 40% methanol, respectively, extract by ultrasonic at 30°C for 30 min, supplement the reduced mass with the same volume fraction of methanol solution and filter to obtain the Xanthoceras sorbifolia tea alcohol extract, and obtain the liquid-to-solid ratio of 40:1 mL / g, 60:1 mL / g, and 80:1 mL / g as the optimized experimental conditions;

[0029] Step 3.4, Effect of extraction time:

[0030] Weigh 6 portions of Xanthoceras sorbifolia tea powder accurately into a triangular flask, 0.5 g each, add 60 times the volume fraction of 40% methanol, perform ultrasonic extraction at 30°C for 15 min, 25 min, 35 min, 45 min, 55 min, and 65 min, respectively, supplement the reduced mass with methanol solution of the same volume fraction and filter to obtain Xanthoceras sorbifolia tea alcohol extract, and the extraction time of 25, 35, and 45 min is the optimized experimental condition;

[0031] Preferably, in step 4, the specific steps of the Box-Behnken response surface screening extraction process parameters are:

[0032] Step 4.1, Box-Behnken response surface design experiment:

[0033] According to the results of the single factor test, three factors, namely methanol concentration (A), liquid-to-solid ratio (B) and extraction time (C), were selected, and the comprehensive score was used as the response value to design a response surface analysis experiment with three factors and three levels; the experimental design factors and levels are shown in Table 1, the experimental design and results are shown in Table 2, and the variance analysis is shown in Table 3;

[0034] Table 1

[0035]

[0036]

[0037] Table 2

[0038] Serial number AMethanol concentration B Liquid to Material Ratio C extraction time Total flavonoids content Tea polyphenols content Extract yield Overall Rating 1 -1 0 1 6.09 2.27 9.27 0.6840 2 1 1 0 4.67 2.73 13.93 0.6551 3 -1 0 -1 6.9 3.25 9.93 0.7839 4 1 1 5.98 2.89 11.68 0.7191 5 0 -1 -1 5.31 3.54 7.25 0.6911 6 0 1 -1 5.27 3.17 11.78 0.7047 7 0 0 0 7.28 3.03 10.55 0.7927 8 0 0 0 5.40 3.83 10.99 0.7625 9 -1 -1 0 8.89 1.47 7.15 0.7076 10 -1 1 1 2.68 2.96 12.2 0.5448 11 0 1 1 4.89 2.62 9.16 0.6066 12 0 -1 1 5.16 3.72 11.07 0.7401 13 1 -1 0 3.39 3.13 9.13 0.5669 14 0 0 0 6.26 3.47 8.79 0.7547 15 0 0 0 5.27 3.54 12.37 0.7438 16 0 0 0 4.63 3.81 12.03 0.7283 17 1 0 -1 5.21 2.79 12.67 0.6776

[0039] Table 3

[0040]

[0041]

[0042] Note: * indicates that P < 0.05 is significantly different; ** indicates that P is less than 0.01 is extremely significant

[0043] Step 4.2, model fitting:

[0044] Design Expert 8.05 software was used to perform multiple regression and binomial analysis on the experimental design and comprehensive score data in Table 2, and the quadratic regression equation model was obtained:

[0045] Y=0.7540-0.0088A-0.0222B-0.0064C-0.0590AB+0.0177AC-0.0179BC-0.0557A 2

[0046] -0.0840B2 +0.0040C 2 ;

[0047] From the results of variance analysis, Table 3 shows that the lack-of-fit term of the quadratic multiple regression equation is not significant (P=0.6842>0.05), and the regression model is extremely significant (P<0.001), indicating that the model fits the actual experiment well;

[0048] Correlation coefficient R 2 =0.9620, Corrected determination coefficient R 2 Adj =0.9132, indicating that the model has a high degree of fit with the data, so the fitted model can be used for the analysis and prediction of the extraction process of Xanthoceras sorbifolia tea leaves; From the F value in Table 3, it can be judged that the order of influence of each factor on the comprehensive score is liquid-to-solid ratio (B) > extraction time (C) > methanol concentration (A), among which methanol concentration and liquid-to-solid ratio have extremely significant effects on the comprehensive score, and the quadratic term A 2 The results showed that the interaction terms AB and AC, BC and methanol concentration had significant effects on the comprehensive score, indicating that the methanol concentration and extraction time, liquid-to-solid ratio and extraction time, and methanol concentration and liquid-to-solid ratio had significant interactive effects on the comprehensive score.

[0049] Step 4.3, response surface optimization:

[0050] Design Expert 8.05 software was used to draw a three-dimensional response surface. By comparing the pairwise interactions of three factors, including methanol concentration, liquid-to-solid ratio and extraction time, it was found that methanol concentration and liquid-to-solid ratio had the most significant effects on the comprehensive score of the Xanthoceras sorbifolia tea extraction process.

[0051] Preferably, in step 4, the result of the Box-Behnken response surface screening of the extraction process parameters is: methanol concentration 58-60%, liquid-to-solid ratio 40:1mL / g-41.72:1mL / g, extraction time 35-min, and the comprehensive score theoretical value is 0.7130.

[0052] Preferably, the methanol concentration is 60%, the liquid-to-solid ratio is 40:1 mL / g, the extraction time is 35 min, and the actual value of the comprehensive score is 0.7033.

[0053] The method involved in the present invention is based on a single factor experiment, selects methanol concentration, liquid-to-solid ratio and extraction time that have a significant impact on Xanthoceras sorbifolia tea leaves as investigation factors, takes total flavonoids, tea polyphenols and extract yield as indicators, adopts a comprehensive scoring method for evaluation, and makes a relatively objective and scientific evaluation of the extraction process of Xanthoceras sorbifolia tea leaves.

[0054] The results of the quadratic regression model variance analysis and the response surface interaction analysis involved in the present invention both show that the methanol concentration and the liquid-to-solid ratio have a significant effect on the extraction of Xanthoceras sorbifolia tea leaves, and with the increase of the methanol concentration or the liquid-to-solid ratio, the comprehensive score first increases and then decreases. This is because the flavonoids and tea polyphenols in the Xanthoceras sorbifolia tea leaves are both polyhydroxy structures and have a certain hydrophilicity, and the polarity of the extraction solvent gradually decreases with the increase of the methanol concentration, and the dissolution rate of the flavonoids and polyphenol components increases within a certain range, but when the methanol concentration is greater than 60%, the non-polar components are competitively dissolved, resulting in a decrease in the yield of the target component; with the increase of the liquid-to-solid ratio, the dissolution rate of the solute is accelerated, but when the liquid-to-solid ratio exceeds 80:1 mL / g, other solutes will also be competitively dissolved, so that the extraction rate of the target product is reduced.

[0055] After optimization, the extraction process of Xanthoceras sorbifolia tea was obtained as follows: liquid-to-solid ratio of 40:1 mL / g, ultrasonic extraction under 60% methanol for 35 min, and the total flavonoids content of Xanthoceras sorbifolia tea was 6.03%, the total polyphenol content was 2.53%, the extract yield was 10.19%, the theoretical comprehensive score was 0.7130, and the measured value was 0.7033, which was close to the model prediction value, indicating that the experimental model has a high degree of fitting and can be applied to the extraction of effective active ingredients in Xanthoceras sorbifolia tea.

[0056] The present invention has the following advantages:

[0057] (1) The present invention adopts a comprehensive scoring method to optimize the extraction process of Xanthoceras sorbifolia tea leaves; specifically, a single factor experiment combined with a response surface analysis method is adopted, methanol concentration, liquid-to-solid ratio, and extraction time are selected as investigation factors, and the total flavonoids, tea polyphenols content, and extract yield are taken as comprehensive indicators. A verification experiment is carried out, and finally the optimal process parameters are obtained: methanol concentration of 58%, liquid-to-solid ratio of 41.72:1 mL / g, extraction time of 35 min, and the theoretical value of the comprehensive score is 0.7130; in order to facilitate actual operation, the optimal extraction process is adjusted to: methanol concentration of 60%, liquid-to-solid ratio of 40:1 mL / g, and extraction time of 35 min.

[0058] (2) The present invention repeated the verification test on the above-mentioned optimized process parameters for 3 times, and finally obtained a comprehensive score of 0.7033 for the Xanthoceras sorbifolia tea leaf extraction process, which is close to the theoretical value and has a relative error of 1.36%. This verifies the method involved in the present invention, that is, it shows that the extraction process parameters of the response surface optimization model are accurate and reliable.

[0059] (3) The method involved in the present invention has strong repeatability, is easy to operate and has high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 is the effect of different factors on the comprehensive score of Xanthoceras sorbifolia tea leaves extraction;

[0061] Figure 2 It is the response surface diagram of the interaction effect of various factors on the comprehensive score of Xanthoceras sorbifolia tea extraction. DETAILED DESCRIPTION

[0062] The present invention is described in detail below in conjunction with specific embodiments. It should be noted that the following embodiments are only further descriptions of the present invention, but the protection scope of the present invention is not limited to the following embodiments.

[0063] Example

[0064] The present embodiment relates to a method for optimizing the extraction process of Xanthoceras sorbifolia tea leaves, the method comprising the following steps: using a single factor experiment combined with a response surface analysis method, selecting methanol concentration, liquid-to-solid ratio, and extraction time as investigation factors, taking total flavonoids, tea polyphenols content, and extract yield as comprehensive indicators, and conducting a verification experiment, and finally obtaining the optimal process parameters. The specific steps of the method are as follows:

[0065] The instruments and materials involved in this embodiment are as follows:

[0066] Gen5 microplate reader (Berteng Instrument, USA); JP-040S Jiemeng brand ultrasonic cleaner (Shenzhen Jiemeng Cleaning Equipment Co., Ltd.); HH.S21-Ni4 electric constant temperature water bath (Beijing 328 Scientific Instrument Co., Ltd.); rutin (batch number: BWB51607); gallic acid (batch number: RS02221120); sodium carbonate (item number: S70007-500G); aluminum nitrate (item number: A96330-500g); sodium nitrite (S28000-500g); folin phenol (F50002-100ML); ultrapure water (Pall Fudi Bioanalytical Instrument Co., Ltd., Shanghai) chromatographic methanol and other reagents were all analytical grade (Tianjin Damao Chemical Reagent Factory).

[0067] Step 1, preparation of Xanthoceras sorbifolia tea leaves;

[0068] Step 2, determination of the content of total flavonoids and tea polyphenols in Xanthoceras sorbifolia tea leaves and the yield of extract;

[0069] Step 3, single factor test;

[0070] Step 4: Box-Behnken response surface screening of extraction process parameters.

[0071] Preferably, in step 1, the Xanthoceras sorbifolia tea preparation process flow is: picking → cleaning → draining → spreading fresh leaves → withering → rolling → frying → drying → finished product.

[0072] Preferably, in step 1, the picking selects the tender leaves at the top of one year old, and cleans them after picking; the greening is the core process of tea making, the greening temperature is 100-120℃, the greening time is 2-3min, and the greening needs to be killed quickly at high temperature to achieve the purpose of completely passivating the activity of oxidase, because the water in the leaves evaporates a lot during greening, making the leaves soft, exuding the original fragrance of Xanthoceras sorbifolia leaves, and the leaves are not easy to loosen by hand; the rolling time is 3-8min, so that the leaves are rolled into ropes, the leaf cells are broken to squeeze out the juice, and the green leaves are fried while hot after the pot is removed from the pot; the greening time is 3-5min, the pot temperature during greening is 240-260℃, and the speed of stir-frying is flexibly controlled according to the degree of heat of the leaves. After drying a little, the second greening is carried out, and the temperature of the drying pot is 200-240℃. When it is hot to the touch, it is taken out of the pot, dried and shaped to obtain the finished product.

[0073] Preferably, in step 2, the specific steps of determining the total flavonoids, tea polyphenols content and extract yield in the Xanthoceras sorbifolia tea leaves are:

[0074] Step 2.1, drying the prepared Xanthoceras sorbifolia tea leaves, crushing them, and passing them through an 80-mesh sieve for later use;

[0075] Step 2.2, determination of total flavonoid content: NaNO2-Al(NO3)3-NaOH colorimetric method was used, rutin was used as reference, and a linear equation was drawn: Y = 0.0467X - 0.0052 (R 2 =0.9996);

[0076] Step 2.3, determination of tea polyphenols content: according to GB / T8313-2018 detection method for tea polyphenols in tea leaves;

[0077] Step 2.4, determination of extract yield: quantitatively measure the methanol extract of Xanthoceras sorbifolia tea leaves, place it in an evaporating dish that has been dried to constant weight, evaporate it in a water bath, place it in a drying oven at 105°C to constant weight, take it out and cool it in a desiccator for 30 minutes, accurately weigh the mass, and calculate the extract yield.

[0078] Preferably, in step 3, the specific steps of the single factor test are as follows:

[0079] Step 3.1, determination of comprehensive scoring weight coefficient:

[0080] Label each component: Comprehensively score the components with total flavonoids, tea polyphenols content and extract yield as indicators. Since total flavonoids are the main antioxidant active component of Xanthoceras sorbifolia tea, it is recorded as 50%, tea polyphenols are relatively minor active ingredients, and it is recorded as 35%. The dry extract yield is marked as 15% as an auxiliary inspection indicator.

[0081] It can be calculated according to the comprehensive scoring formula, which is as follows: Comprehensive score = flavonoid content in each sample / the highest flavonoid content in the group of samples × 50% + tea polyphenol content in each sample / the highest tea polyphenol content in the group of samples × 35% + extract yield in each sample / the highest extract yield in the group of samples × 15%;

[0082] Step 3.2, Effect of methanol concentration:

[0083] Accurately weigh 6 portions of Xanthoceras sorbifolia tea powder in a triangular flask, 0.5 g each, add 40 times the volume fraction of 0%, 20%, 40%, 60%, 80%, 100% methanol, respectively, extract by ultrasonic at 30°C for 30 min, supplement the reduced mass with the same volume fraction of methanol solution and filter to obtain Xanthoceras sorbifolia tea alcohol extract; obtain the optimized experimental conditions of 20%, 40%, 60% methanol concentration; from Figure 1 -A shows that with the increase of methanol concentration, the comprehensive score of Xanthoceras sorbifolia tea leaf extraction rate first increases and then decreases, reaching the highest value when the methanol concentration is 40%, so methanol concentrations of 20%, 40%, and 60% are selected as the optimized experimental conditions;

[0084] Step 3.3, influence of liquid-to-solid ratio:

[0085] Weigh 6 portions of Xanthoceras sorbifolia tea powder accurately into a triangular flask, 0.5 g each, add 20, 40, 60, 80, 100, and 120 times the volume fraction of 40% methanol, respectively, extract by ultrasonic at 30°C for 30 min, supplement the reduced mass with the same volume fraction of methanol solution and filter to obtain the Xanthoceras sorbifolia tea alcohol extract, and obtain the liquid-to-solid ratio of 40:1 mL / g, 60:1 mL / g, and 80:1 mL / g as the optimized experimental conditions;

[0086] Depend on Figure 1 -B shows that with the increase of liquid-to-solid ratio, the comprehensive score gradually increases with the increase of liquid-to-solid ratio, reaches the highest value at 60:1 (mL / g), and then tends to be stable, so liquid-to-solid ratios of 40:1, 60:1 and 80:1 (mL / g) are selected as the optimized experimental conditions;

[0087] Step 3.4, Effect of extraction time:

[0088] Weigh 6 portions of Xanthoceras sorbifolia tea powder accurately into a triangular flask, 0.5 g each, add 60 times the volume fraction of 40% methanol, perform ultrasonic extraction at 30°C for 15 min, 25 min, 35 min, 45 min, 55 min, and 65 min, respectively, supplement the reduced mass with methanol solution of the same volume fraction and filter to obtain Xanthoceras sorbifolia tea alcohol extract, and the extraction time of 25, 35, and 45 min is the optimized experimental condition;

[0089] Depend on Figure 1 -C shows that with the increase of extraction time, the comprehensive score first increases and then decreases, reaching the highest value when the extraction time is 35 min. Therefore, extraction times of 25, 35, and 45 min are selected as the optimized experimental conditions.

[0090] Preferably, in step 4, the specific steps of the Box-Behnken response surface screening extraction process parameters are:

[0091] Step 4.1, Box-Behnken response surface design experiment:

[0092] According to the results of single factor test, three factors, namely methanol concentration (A), liquid-to-solid ratio (B) and extraction time (C), were selected, and the comprehensive score was used as the response value to design a response surface analysis experiment with three factors and three levels.

[0093] Step 4.2, model fitting:

[0094] Design Expert 8.05 software was used to perform multiple regression and binomial analysis on the comprehensive score data in Table 2 above, and the quadratic regression equation model was obtained:

[0095] Y=0.7540-0.0088A-0.0222B-0.0064C-0.0590AB+0.0177AC-0.0179BC-0.0557A 2

[0096] -0.0840B 2 +0.0040C 2 ;

[0097] Step 4.3, response surface optimization:

[0098] Design Expert 8.05 software was used to draw the three-dimensional response surface. Figure 2 Shown by: Figure 2 -a, the bottom surface is composed of A methanol concentration and B liquid-to-solid ratio, and the ordinate is the comprehensive score. When the methanol concentration remains unchanged, the comprehensive score increases first and then decreases with the increase of the liquid-to-solid ratio; when the liquid-to-solid ratio remains unchanged, the comprehensive score increases first and then decreases with the increase of the methanol concentration; Figure 2 -b shows that the bottom surface is composed of A methanol concentration and C extraction time, and the ordinate is the comprehensive score. The comprehensive score first increases and then decreases with the increase of methanol concentration, and changes more slowly with the increase of extraction time; Figure 2-c shows that the bottom is composed of B liquid-to-solid ratio and C extraction time, and the ordinate is the comprehensive score. When relative to the extraction time, methanol concentration is the main factor affecting the comprehensive score. By comparing the interaction between the three factors of methanol concentration, liquid-to-solid ratio and extraction time, it can be found that methanol concentration and liquid-to-solid ratio have the most significant effects on the comprehensive score of Xanthoceras sorbifolia tea extraction process.

[0099] Preferably, in step 4, the result of the Box-Behnken response surface screening of the extraction process parameters is: methanol concentration 58-60%, liquid-to-solid ratio 40:1mL / g-41.72:1mL / g, extraction time 35-min, and the comprehensive score theoretical value is 0.7130.

[0100] Preferably, the methanol concentration is 60%, the liquid-to-solid ratio is 40:1 mL / g, the extraction time is 35 min, and the actual value of the comprehensive score is 0.7033.

[0101] Verification results: The verification test was repeated three times based on the improved optimal process conditions, and the actual comprehensive score of the Xanthoceras sorbifolia tea extraction process was 0.7033, which was close to the theoretical value of 0.7130, and the relative error was only 1.36%, indicating that the response surface optimization model method for extracting process parameters is very accurate and reliable.

[0102] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which will not affect the essence of the present invention.

Claims

1. A method for optimizing the extraction process of Xanthoceras sorbifolia tea leaves, characterized in that: The method comprises the following steps: Step 1, preparation of Xanthoceras sorbifolia tea leaves; Step 2, determination of the content of total flavonoids and tea polyphenols in Xanthoceras sorbifolia tea leaves and the yield of extract; Step 3, single factor test; Step 4: Box-Behnken response surface screening of extraction process parameters.

2. The method for optimizing the extraction process of Xanthoceras sorbifolia tea leaves according to claim 1, characterized in that: In step 1, the process flow of preparing Xanthoceras sorbifolia tea leaves is as follows: picking → cleaning → draining → spreading fresh leaves → withering → rolling → frying → drying → finished product.

3. The method for optimizing the extraction process of Xanthoceras sorbifolia tea leaves according to claim 2, characterized in that: In step 1, the picking is to select the tenderer leaves at the top of one-year-old leaves, and clean them after picking; the fixing temperature is 100-120°C, and the fixing time is 2-3min; the rolling time is 3-8min, the stir-frying time is 3-5min, the pan temperature during stir-frying is 240-260°C, and the pan temperature for drying is 200-240°C.

4. The method for optimizing the extraction process of Xanthoceras sorbifolia tea leaves according to claim 1, characterized in that: In step 2, the specific steps of determining the total flavonoids, tea polyphenols content and extract yield in the Xanthoceras sorbifolia tea leaves are: Step 2.1, drying the prepared Xanthoceras sorbifolia tea leaves, crushing them, and passing them through an 80-mesh sieve for later use; Step 2.2, determination of total flavonoid content: NaNO2-Al(NO3)3-NaOH colorimetric method was used, rutin was used as reference, and a linear equation was drawn: Y = 0.0467X - 0.0052 (R 2 =0.9996); Step 2.3, determination of tea polyphenols content: according to GB / T8313-2018 detection method for tea polyphenols in tea leaves; Step 2.4, determination of extract yield: quantitatively measure the methanol extract of Xanthoceras sorbifolia tea leaves, place it in an evaporating dish that has been dried to constant weight, evaporate it in a water bath, place it in a drying oven at 105°C to constant weight, take it out and cool it in a desiccator for 30 minutes, accurately weigh the mass, and calculate the extract yield; wherein, the methanol concentration is 58%, the liquid-to-solid ratio is 41.72:1 mL / g, and the extraction time is 35 minutes.

5. The method for optimizing the extraction process of Xanthoceras sorbifolia tea leaves according to claim 1, characterized in that: In step 3, the specific steps of the single factor test are as follows: Step 3.1, determination of comprehensive scoring weight coefficient: Label each ingredient: Comprehensively score the ingredients using the total flavonoids, tea polyphenols content and extract yield as indicators, with total flavonoids recorded as 50%, tea polyphenols recorded as 35%, and dry extract yield recorded as 15%; It can be calculated according to the comprehensive scoring formula, which is as follows: Comprehensive score = flavonoid content in each sample / the highest flavonoid content in the group of samples × 50% + tea polyphenol content in each sample / the highest tea polyphenol content in the group of samples × 35% + extract yield in each sample / the highest extract yield in the group of samples × 15%; Step 3.2, Effect of methanol concentration: Accurately weigh 6 portions of Xanthoceras sorbifolia tea powder in a triangular flask, 0.5 g each, and add 40 times the volume fraction of 0%, 20%, 40%, 60%, 80%, and 100% methanol, respectively. After ultrasonic extraction at 30°C for 30 minutes, supplement the reduced mass with the same volume fraction of methanol solution and filter to obtain the Xanthoceras sorbifolia tea alcohol extract; the methanol concentrations of 20%, 40%, and 60% were obtained as the optimized experimental conditions; Step 3.3, influence of liquid-to-solid ratio: Weigh 6 portions of Xanthoceras sorbifolia tea powder accurately into a triangular flask, 0.5 g each, add 20, 40, 60, 80, 100, and 120 times the volume fraction of 40% methanol, respectively, extract by ultrasonic at 30°C for 30 min, supplement the reduced mass with the same volume fraction of methanol solution and filter to obtain the Xanthoceras sorbifolia tea alcohol extract, and obtain the liquid-to-solid ratio of 40:1 mL / g, 60:1 mL / g, and 80:1 mL / g as the optimized experimental conditions; Step 3.4, Effect of extraction time: Accurately weigh 6 portions of Xanthoceras sorbifolia tea powder in a triangular flask, 0.5 g each, add 60 times the volume fraction of 40% methanol, and perform ultrasonic extraction at 30°C for 15 min, 25 min, 35 min, 45 min, 55 min, and 65 min, respectively. Supplement the reduced mass with methanol solution of the same volume fraction and filter to obtain the Xanthoceras sorbifolia tea alcohol extract. The extraction time of 25, 35, and 45 min is the optimized experimental condition.

6. The method for optimizing the extraction process of Xanthoceras sorbifolia tea leaves according to claim 1, characterized in that: In step 4, the specific steps of the Box-Behnken response surface screening extraction process parameters are: Step 4.1, Box-Behnken response surface design experiment: According to the results of single factor test, three factors, namely methanol concentration, liquid-to-solid ratio and extraction time, were selected, and the comprehensive score was used as the response value to design a response surface analysis experiment with three factors and three levels. Step 4.2, model fitting: Design Expert 8.05 software was used to perform multiple regression and binomial analysis on the experimental design and comprehensive score data, and the quadratic regression equation model was obtained: <h2 style=";text-align:left;direction:ltr">Y = 0.7540 - 0.0088A - 0.0222B - 0.0064C - 0.0590AB + 0.0177AC - 0.0179BC - 0.0557A<h2 style=";text-align:left;direction:ltr"> 2 -0.0840B 2 +0.0040C 2 ; Step 4.3, response surface optimization: Design Expert 8.05 software was used to draw a three-dimensional response surface. By comparing the pairwise interactions of three factors, including methanol concentration, liquid-to-solid ratio and extraction time, it was found that methanol concentration and liquid-to-solid ratio had the most significant effects on the comprehensive score of the Xanthoceras sorbifolia tea extraction process.

7. The method for optimizing the extraction process of Xanthoceras sorbifolia tea leaves according to claim 6, characterized in that: In step 4, the results of the Box-Behnken response surface screening of extraction process parameters are: methanol concentration 58-60%, liquid-to-solid ratio 40:1mL / g-41.72:1mL / g, extraction time 35-min, and the comprehensive score theoretical value is 0.7130.

8. The method for optimizing the extraction process of Xanthoceras sorbifolia tea leaves according to claim 7, characterized in that: The methanol concentration was 60%, the liquid-to-solid ratio was 40:1 mL / g, the extraction time was 35 min, and the actual value of the comprehensive score was 0.7033.

9. The method for optimizing the extraction process of Xanthoceras sorbifolia tea leaves according to claim 6, characterized in that: Methanol concentration and liquid-to-solid ratio have a significant effect on the extraction of Xanthoceras sorbifolia tea leaves. With the increase of methanol concentration or liquid-to-solid ratio, the comprehensive score first increases and then decreases. Specifically, both flavonoids and tea polyphenols in Xanthoceras sorbifolia tea leaves belong to polyhydroxy structures and have certain hydrophilicity. The polarity of the extraction solvent gradually decreases with the increase of methanol concentration. The dissolution rate of flavonoids and polyphenol components increases within a certain range, but when the methanol concentration is greater than 60%, non-polar components are competitively dissolved, resulting in a decrease in the yield of the target component; with the increase of liquid-to-solid ratio, the dissolution rate of the solute is accelerated, but when the liquid-to-solid ratio exceeds 80:1mL / g, other solutes will also be competitively dissolved, reducing the extraction rate of the target product.

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