Method for optimizing gastrodia elata polysaccharide extraction conditions by response surface method

Abstract

The invention discloses a method for optimizing gastrodia elata polysaccharide extraction conditions by using a response surface method.The method comprises the following steps that S1, pretreatment of a gastrodia elata raw material is conducted, specifically, high-quality gastrodia elata is selected, washed, dried, smashed and screened, and gastrodia elata powder is obtained; s2, single-factor test: determining three factors, namely a material-liquid ratio, extraction time and extraction temperature, and determining the influence of a certain factor on the gastrodia elata polysaccharide extraction rate of the gastrodia elata powder under the condition that other conditions are not changed; and S3, response surface test design: according to a single factor test result, selecting a material-liquid ratio, extraction time and extraction temperature as independent variables, taking the gastrodia elata polysaccharide extraction rate as a response value, performing regression analysis on response surface test data by adopting Design Expert software, and establishing a quadratic polynomial model to obtain a multivariate quadratic regression equation: Y = 21.58-1.15 X1 + 3.95 X2 + 3.5 X3 + 0.2 X1 X2-0.7 X1 X3-1.70 X2 X3-4.69 X1 X1-3.89 X2 X2-5.99 X3 X3. The optimal extraction condition can be rapidly and accurately determined, the extraction rate of the gastrodia elata polysaccharide is improved, the extraction process is simplified, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of natural product extraction, and in particular to a method for optimizing gastrodia elata polysaccharide extraction conditions by utilizing response surface methodology. Background Art

[0002] Gastrodia elata, also known as red arrow, Dingfeng grass, and Duyaozhi, is a plant of the genus Gastrodia of the orchid family. According to Shennong's Herbal Classic and Compendium of Materia Medica, Gastrodia elata (Gastrodiaelata Bl.) has very good pharmacological effects and is a traditional precious medicine. Gastrodia elata has a good therapeutic effect on diseases such as pediatric convulsions, memory loss, sciatica, dizziness, and epilepsy. At present, many compounds have been isolated and identified from Gastrodia elata. In addition to Gastrodia elata phenols and phenolic glycosides, it also contains compounds such as sterols, organic acids, and polysaccharides. As one of the main active ingredients of Gastrodia elata, Gastrodia elata polysaccharide has multiple physiological activities such as anti-oxidation, immunomodulation, and neuroprotection, and has broad application prospects in the fields of medicine and health care products.

[0003] The main methods for extracting Gastrodia elata polysaccharides include water extraction, ultrasonic-assisted extraction, microwave-assisted extraction, enzyme extraction and supercritical fluid extraction, but compared with water extraction, other methods have problems such as complex process and high cost. At present, the process conditions of water extraction remain at the process parameters (solid-liquid ratio, extraction temperature, extraction time, etc.) found by the single factor control variable method, and there is a lack of using the response surface method to establish a continuous variable surface model to optimize the water extraction conditions of Gastrodia elata polysaccharides. Summary of the invention

[0004] Under this background condition, the present invention proposes a method for optimizing the extraction conditions of Gastrodia elata polysaccharide by using response surface methodology and its preparation method, selects suitable Gastrodia elata raw materials and performs pretreatment, then, through single factor experiment, investigates the influence of extraction temperature, extraction time, and solid-liquid ratio on the extraction rate of Gastrodia elata polysaccharide, takes the optimal point of the single factor experiment as the center, and takes a level value above and below the optimal point as the approximate range of each factor. Then, according to the results of the single factor experiment, the response surface experiment scheme is designed, and the three factors of extraction temperature, extraction time, and solid-liquid ratio are optimized with the polysaccharide extraction rate as the response value. The response surface experiment data are analyzed by statistical analysis software, and a mathematical model is established to obtain the optimal combination of each factor.

[0005] In order to overcome at least one of the above disadvantages of the prior art, the present invention provides a method for optimizing the extraction conditions of Gastrodia elata polysaccharides using response surface methodology, comprising the following steps:

[0006] S1 Pretreatment of Gastrodia elata raw materials: Select high-quality Gastrodia elata, wash and dry it, and then crush and sieve it to obtain Gastrodia elata powder;

[0007] S2 single factor test: determine the three factors of solid-liquid ratio, extraction time and extraction temperature, and measure the effect of one factor on the extraction rate of Gastrodia elata polysaccharide while keeping other conditions unchanged;

[0008] S3 response surface test design: According to the results of the single factor test, the solid-liquid ratio, extraction time and extraction temperature were selected as independent variables, and the extraction rate of Gastrodia elata polysaccharide was used as the response value. The response surface test data were regressed using the Design Expert software, and a quadratic polynomial model was established to obtain the multivariate quadratic regression equation:

[0009] Y=21.58-1.15X1+3.95X2+3.5X3+0.2X1X2-0.7X1X3-1.70X2X3-4.69X1X1-3.89X2X2-5.99X3X3;

[0010] Among them, Y is the extraction rate of Gastrodia elata polysaccharide, variable parameter X1 is the solid-liquid ratio, X2 is the extraction time, and X3 is the extraction temperature.

[0011] Furthermore, the crushing and screening is specifically crushing to pass through a 60-mesh sieve.

[0012] Furthermore, the selection ranges of the three factors are solid-liquid ratio 1:15-1:35; extraction time 0.5-2.5h; extraction temperature 30°C-70°C.

[0013] Furthermore, the specific operation of the effect of the solid-liquid ratio on the extraction rate of Gastrodia elata polysaccharide in the S2 single factor experiment is as follows: weigh the pretreated Gastrodia elata powder, mix it with water at a solid-liquid ratio of 1:15, 1:20, 1:25, 1:30 and 1:35, respectively, extract it at 60°C for 1.5h, centrifuge it, collect the supernatant, add anhydrous ethanol to the alcohol precipitation concentration, precipitate it overnight, filter it, collect the filter residue and freeze-dry it to obtain Gastrodia elata polysaccharide, and calculate the extraction rate of Gastrodia elata polysaccharide.

[0014] Furthermore, the specific operation of the effect of extraction time on the extraction rate of Gastrodia elata polysaccharide in the S2 single factor experiment is as follows: weigh the pretreated Gastrodia elata powder, mix it at a solid-liquid ratio of 1:25, extract it at 60°C for 0.5h, 1h, 1.5h, 2h, and 2.5h, respectively, centrifuge it, collect the supernatant, add anhydrous ethanol to the alcohol precipitation concentration, precipitate it overnight, filter it, collect the filter residue, and freeze-dry it to obtain Gastrodia elata polysaccharide, and calculate the extraction rate of Gastrodia elata polysaccharide.

[0015] Furthermore, the specific operation of the effect of extraction temperature on the extraction rate of Gastrodia elata polysaccharide in the S2 single factor experiment is as follows: weigh the pretreated Gastrodia elata powder, mix it at a solid-liquid ratio of 1:25, extract it at 30°C, 40°C, 50°C, 60°C, and 70°C for 1.5 hours, centrifuge it, collect the supernatant, add anhydrous ethanol to the alcohol precipitation concentration, precipitate it overnight, filter it, collect the filter residue, and freeze-dry it to obtain Gastrodia elata polysaccharide, and calculate the Gastrodia elata polysaccharide extraction rate.

[0016] Furthermore, the centrifugal conditions are: 6000-8000 r / min, 10-20 min.

[0017] Furthermore, the alcohol precipitation concentration is 80%.

[0018] Furthermore, the alcohol precipitation temperature is 4°C.

[0019] Furthermore, the S3 response surface experimental design also includes: evaluating the significance and goodness of fit of the model through the variance analysis method, analyzing the influence of the interaction between the three factors on the extraction rate, and determining the optimal level combination of each factor. After analysis, the optimal extraction conditions are: extraction temperature 55°C, extraction time 1.75 hours, and solid-liquid ratio 1:26.

[0020] The beneficial effect of the present invention is that the response surface method is used to optimize the extraction process conditions of Gastrodia elata polysaccharide on the basis of a single factor experiment. The three conditions of solid-liquid ratio, extraction temperature and extraction time are determined to have a significant effect on the extraction rate of Gastrodia elata polysaccharide. On the basis of the single factor experiment, a three-factor three-level orthogonal experiment is designed, and the extraction conditions of Gastrodia elata polysaccharide are optimized by the response surface method. The optimal extraction conditions can be determined quickly and accurately, the extraction rate of Gastrodia elata polysaccharide is improved, the extraction process is simplified, the production cost is reduced, and the industrial production and further application of Gastrodia elata polysaccharide are facilitated. Finally, the optimal process conditions for extracting Gastrodia elata polysaccharide are determined: extraction temperature 55°C, extraction time 1.75 hours, solid-liquid ratio 1:26, which provides a reference basis for the development and utilization of Gastrodia elata polysaccharide. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0022] Figure 1 This is a graph showing the effect of the solid-liquid ratio on the extraction rate of Gastrodia elata polysaccharide in the embodiments of the present invention;

[0023] Figure 2 This is a graph showing the effect of extraction time on the extraction rate of Gastrodia elata polysaccharide in an embodiment of the present invention;

[0024] Figure 3 This is a graph showing the effect of extraction temperature on the extraction rate of Gastrodia elata polysaccharide in an embodiment of the present invention;

[0025] Figure 4 This is the ultraviolet spectrum of Gastrodia elata polysaccharide in the embodiment of the present invention;

[0026] Figure 5 This is a graph showing the effect of the solid-liquid ratio and the extraction temperature on the extraction rate of Gastrodia elata polysaccharide in the embodiment of the present invention;

[0027] Figure 6 This is a graph showing the effect of extraction time and material-liquid ratio on the extraction rate of Gastrodia elata polysaccharide in an embodiment of the present invention;

[0028] Figure 7 This is a graph showing the effects of extraction temperature and extraction time on the extraction rate of Gastrodia elata polysaccharides in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] It should be mentioned before discussing the exemplary embodiments in more detail that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe the operations as sequential processes, many of the operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but can also have additional steps not included in the accompanying drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0030] It should be understood that, although the terms "first", "second", etc. may be used herein to describe various units, these units should not be limited by these terms. These terms are used only to distinguish one unit from another unit. For example, without departing from the scope of the exemplary embodiments, the first unit may be referred to as the second unit, and similarly the second unit may be referred to as the first unit. The term "and / or" used herein includes any and all combinations of one or more of the listed associated items.

[0031] The present invention provides a method for optimizing the extraction conditions of gastrodia elata polysaccharide by using response surface methodology, comprising:

[0032] S1 Pretreatment of Gastrodia elata raw materials: Select high-quality Gastrodia elata, wash and dry it, and then crush and sieve it to obtain Gastrodia elata powder;

[0033] S2 single factor test: determine the three factors of solid-liquid ratio (ratio of Gastrodia elata powder to extract water), extraction time and extraction temperature, and determine the effect of a certain factor on the extraction rate of Gastrodia elata polysaccharide while keeping other conditions unchanged.

[0034] S3 response surface test design: According to the results of the single factor test, the solid-liquid ratio, extraction time and extraction temperature were selected as independent variables, and the extraction rate of Gastrodia elata polysaccharide was used as the response value. The response surface test data were regressed using the Design Expert software, and a quadratic polynomial model was established to obtain the multivariate quadratic regression equation:

[0035] Y=21.58-1.15X1+3.95X2+3.5X3+0.2X1X2-0.7X1X3-1.70X2X3-4.69X1X1-3.89X2X2-5.99X3X3;

[0036] Among them, Y is the extraction rate of Gastrodia elata polysaccharide, variable parameter X1 is the solid-liquid ratio, X2 is the extraction time, and X3 is the extraction temperature.

[0037] Example 1

[0038] S1 Pretreatment of Gastrodia elata raw materials: Select high-quality Gastrodia elata, wash and dry it, and then crush it to pass through a 60-mesh sieve.

[0039] S2 single factor test: Gastrodia elata powder was extracted at 30℃~70℃ for 0.5~2.5h at a solid-liquid ratio of 1:15~1:35, and the effect of a certain factor on the extraction rate of Gastrodia elata polysaccharide was determined while other conditions remained unchanged.

[0040] Effect of solid-liquid ratio on the extraction rate of Gastrodia elata polysaccharide: Weigh the pretreated Gastrodia elata powder, mix it in the ratio of solid-liquid (the extracting liquid is water) of 1:15, 1:20, 1:25, 1:30, and 1:35, extract it at 60°C for 1.5h, centrifuge it (8000r / min, 10min), collect the supernatant, add anhydrous ethanol to the alcohol precipitation concentration reaching 80%, precipitate it at 4°C overnight, filter it, collect the filter residue and freeze-dry it to obtain Gastrodia elata polysaccharide, and calculate the extraction rate of Gastrodia elata polysaccharide.

[0041] The calculation formula of the extraction rate of Gastrodia elata polysaccharide is: Y (%) = mass of Gastrodia elata polysaccharide / mass of Gastrodia elata raw material powder × 100%. The ratio of raw material to extracting liquid (water) is a parameter that significantly affects the extraction rate.

[0042] Qualitative analysis: UV spectroscopy analysis: UV-visible spectrophotometer is used to scan Gastrodia elata polysaccharides. Figure 4 It can be seen that Gastrodia elata polysaccharide has a characteristic absorption peak at 190nm.

[0043] Purity detection of Gastrodia elata polysaccharide: The purified crude Gastrodia elata polysaccharide was quantified by combining the phenol-sulfuric acid method and the DNS method.

[0044] Table 1

[0045]

[0046] Figure 1 The figure below is the effect of the material-liquid ratio on the extraction rate of Gastrodia elata polysaccharide. It can be seen from the analysis that when the ratio of raw material to liquid is 1:25, the extraction rate of Gastrodia elata polysaccharide reaches a maximum value of 20%. The possible reason is that with the increase of the extraction material-liquid ratio, the mass transfer power will increase, making the contact area between the Gastrodia elata raw material powder and the water solvent larger, and the polysaccharide diffused into the water will also increase, resulting in the dissolution of water-soluble polysaccharides. The reason why the polysaccharide extraction rate decreases when the ratio is higher than 1:25 may be that the Gastrodia elata polysaccharide is basically dissolved in water at 1:25. At this time, the increase in the amount of water will increase the amount of solution in the subsequent alcohol precipitation, increasing the loss of Gastrodia elata polysaccharide.

[0047] Effect of extraction time on the extraction rate of Gastrodia elata polysaccharide: Weigh 1 g of pretreated Gastrodia elata powder, mix it at a solid-liquid ratio of 1:25, extract it at 60°C for 0.5h, 1h, 1.5h, 2h, and 2.5h, centrifuge it (8000r / min, 10min), collect the supernatant, add anhydrous ethanol to the alcohol precipitation concentration reaching 80%, precipitate it at 4°C overnight, filter it, collect the filter residue, and freeze-dry it to obtain Gastrodia elata polysaccharide. The extraction rate of Gastrodia elata polysaccharide was calculated.

[0048] Table 2

[0049]

[0050] Figure 2 The figure below shows the effect of extraction time on the extraction rate of Gastrodia elata polysaccharide. Analysis shows that the extraction time of Gastrodia elata polysaccharide shows an upward trend when it is 0.5-1.5h; the extraction rate reaches the maximum level of 21.6% at 1.5h; and the extraction rate decreases with time when it is 1.5-2.5h. The possible reason for the decrease in extraction rate as the extraction time increases is that as the extraction time increases, in addition to polysaccharides, other components in plant cells such as proteins, pigments, tannins, etc. will also be dissolved in large quantities. These impurities will interact with polysaccharides and may form complexes or colloids, which will increase the viscosity and complexity of the extract, hinder the dissolution and separation of polysaccharides, and reduce the extraction rate of polysaccharides. In addition, long-term high temperature and water will hydrolyze the glycosidic bonds of polysaccharides, destroying the original complete polysaccharide structure and making it difficult to extract it completely, thereby reducing the extraction rate.

[0051] Effect of temperature on the extraction rate of Gastrodia elata polysaccharide: Weigh 1 g of pretreated Gastrodia elata powder, mix it at a solid-liquid ratio of 1:25, extract it at 30℃, 40℃, 50℃, 60℃, and 70℃ for 1.5 h, centrifuge it (8000r / min, 10min), collect the supernatant, add anhydrous ethanol to the alcohol precipitation concentration reaching 80%, precipitate it at 4℃ overnight, filter it, collect the filter residue, and freeze-dry it to obtain Gastrodia elata polysaccharide. The extraction rate of Gastrodia elata polysaccharide was calculated.

[0052] Table 3

[0053]

[0054] Figure 3 The figure shows the effect of material extraction temperature on the extraction rate of Gastrodia elata polysaccharide. It can be seen from the analysis that the extraction rate of Gastrodia elata polysaccharide gradually increases in the range of 30-50℃, reaching a maximum value of 20.3% at 50℃. When the temperature exceeds 50℃, the extraction rate of Gastrodia elata polysaccharide decreases slightly. The reason for this result may be that as the temperature increases, the molecular movement accelerates, the solubility increases, and the corresponding extraction rate also increases. When the temperature exceeds 50℃, it may be unfavorable for the dissolution of polysaccharide molecules, resulting in a decrease in the polysaccharide extraction rate and a decrease in purity.

[0055] S3 response surface test design: According to the results of the single factor test, the solid-liquid ratio, extraction time and extraction temperature were selected as independent variables, and the extraction rate of Gastrodia elata polysaccharide was used as the response value. The response surface test data were regressed using the Design Expert software, and a quadratic polynomial model was established to obtain the multivariate quadratic regression equation:

[0056] Y=21.58-1.15X1+3.95X2+3.5X3+0.2X1X2-0.7X1X3-1.70X2X3-4.69X1X1-3.89X2X2-5.

[0057] 99X3X3; where Y is the extraction rate of Gastrodia elata polysaccharide, variable parameter X1 is the solid-liquid ratio, X2 is the extraction time, and X3 is the extraction temperature. The significance and goodness of fit of the model were evaluated by variance analysis and other methods. The effects of the interactions between the factors on the extraction rate were analyzed to determine the optimal level combination of the factors. The optimal extraction conditions obtained by analysis were: extraction temperature 55°C, extraction time 1.75 hours, and solid-liquid ratio 1:26.

[0058] Based on the single factor experiment, temperature, time and solid-liquid ratio were selected as factors. The polysaccharide extraction rate was used as the evaluation standard. The Dedign Expert software was used to design a three-factor three-level response surface experiment to determine the optimal level of the extraction amount.

[0059] Table 4 Response surface factors and coding levels

[0060]

[0061] In order to optimize the extraction parameters, the interaction of three factors, namely, solid-liquid ratio, time and temperature, on the extraction rate was analyzed. The BBD under RSM was designed as a table. Under different interactions, the extraction rate of Gastrodia elata polysaccharide was different, ranging from 2 to 24.4%. When the ratio of raw material (Gastrodia elata powder) to liquid (water) was 1:26, the extraction time was 1.75 h, and the extraction temperature was 55 °C, the extraction rate reached 24.4%.

[0062] Table 5 Response surface experimental design and extraction rate

[0063]

[0064]

[0065] The extraction rate of Gastrodia elata polysaccharides and the second-order polynomial equation of the three variables were analyzed by Design-Expert software. The equation is as follows:

[0066] Y=21.58-1.15X1+3.95X2+3.5X3+0.2X1X2-0.7X1X3-1.70X2X3-4.69X1X1-3.89X2X2-5.99X3X3, where Y is the extraction rate of Gastrodia elata polysaccharide, variable parameter X1 is the solid-liquid ratio, X2 is the extraction time, and X3 is the extraction temperature.

[0067] The variance analysis of the regression model of Gastrodia elata polysaccharide extraction rate is shown in Table 6. It can be seen from Table 6 that the model is significant and the lack of fit term is not significant. Therefore, the model can make a scientific analysis of most of the changes in the corresponding values.

[0068] Table 6 ANOVA results of response surface quadratic model

[0069]

[0070]

[0071] The slope of the response surface can reflect the degree of influence of the change of factor level on the response value. The larger the slope of the response surface, the greater the influence. The extraction rate of Gastrodia elata polysaccharide fluctuates with the change of factor interaction. Figure 5 It can be seen that when the extraction temperature is fixed at 55°C, the polysaccharide extraction rate first increases and then decreases with the increase of the solid-liquid ratio; when the solid-liquid ratio is fixed at 1:26, the polysaccharide extraction rate first increases and then decreases with the increase of temperature; when the solid-liquid ratio is 1:26 and the temperature is 55°C, the polysaccharide extraction rate reaches the maximum value. Figure 6 It can be seen that when the extraction time is fixed at 1.75h, the polysaccharide extraction rate first increases and then decreases with the increase of the solid-liquid ratio; when the solid-liquid ratio is fixed at 1:26, the polysaccharide extraction rate first increases and then decreases with the increase of the extraction time; when the extraction time is 1.75h and the solid-liquid ratio is 1:26, the polysaccharide extraction rate reaches the maximum value. Figure 7 It can be seen that when the extraction time is fixed at 1.75h, the polysaccharide extraction rate first increases and then decreases with the increase of extraction temperature; when the extraction temperature is fixed at 55℃, the polysaccharide extraction rate first increases and then decreases with the increase of extraction time; when the solid-liquid ratio is fixed at 1:26, the extraction time is 1.75h, and the extraction temperature is 55℃, the polysaccharide extraction rate reaches the maximum value.

[0072] Verification test:

[0073] Three parallel validation tests were conducted under the above optimal extraction conditions. The experimental method referred to the single factor method. The three factors were a solid-liquid ratio of 1:26, an extraction time of 1.75 h, and an extraction temperature of 55 ° C. The average extraction rate was calculated and compared with the model prediction value. If the two are close, it means that the model is reliable and the extraction conditions are successfully optimized.

[0074] According to the results of the Box-Behnken test and the quadratic polynomial regression equation, and using the Design-Expert software, the optimal extraction conditions of each factor for the highest extraction rate of Gastrodia elata polysaccharide in this test were obtained as follows: the solvent (water) multiple was 26, the extraction time was 1.75h, and the extraction temperature was 55°C. Under these conditions, the extraction rate of Gastrodia elata crude polysaccharide was 24.4%. The optimized extraction conditions were verified by a test, which was repeated 3 times, and the test results are shown in Table 7.

[0075] Table 7

[0076]

[0077] Under the above-mentioned optimized extraction conditions (i.e., when the solid-liquid ratio was 26, the extraction time was 1.75h, and the extraction temperature was 55°C), referring to the single factor method, other operating conditions remained unchanged, and the average value of the three groups of experiments was 21.64%, which was 11.31% relative to the 24.4% predicted by the regression equation, and was within the allowable error range (20%), indicating that the regression model of the response surface methodology in the optimization experiment of Gastrodia elata polysaccharide extraction conditions was more reliable.

[0078] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field know all the common technical knowledge in the technical field of the invention before the application date or priority date, can know all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the scope of protection of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for optimizing the extraction conditions of Gastrodia elata polysaccharides using response surface methodology, characterized in that: The steps include: S1 Pretreatment of Gastrodia elata raw materials: Select high-quality Gastrodia elata, wash and dry it, and then crush and sieve it to obtain Gastrodia elata powder; S2 single factor test: determine the three factors of solid-liquid ratio, extraction time and extraction temperature, and measure the effect of one factor on the extraction rate of Gastrodia elata polysaccharide while keeping other conditions unchanged; S3 response surface test design: According to the results of the single factor test, the solid-liquid ratio, extraction time and extraction temperature were selected as independent variables, and the extraction rate of Gastrodia elata polysaccharide was used as the response value. The response surface test data were regressed using the Design Expert software, and a quadratic polynomial model was established to obtain the multivariate quadratic regression equation: Y=21.58-1.15X1+3.95X2+3.5X3+0.2X1X2-0.7X1X3-1.70X2X3-4.69X1X1-3.89X2X2-5.99X3X3; Among them, Y is the extraction rate of Gastrodia elata polysaccharide, variable parameter X1 is the solid-liquid ratio, X2 is the extraction time, and X3 is the extraction temperature.

2. The method for optimizing the extraction conditions of Gastrodia elata polysaccharides using response surface methodology according to claim 1, characterized in that: The crushing and screening specifically includes crushing until the powder passes through a 60-mesh sieve.

3. The method for optimizing the extraction conditions of Gastrodia elata polysaccharides using response surface methodology according to claim 1, characterized in that: The selection ranges of the three factors are solid-liquid ratio 1:15-1:35; extraction time 0.5-2.5h; extraction temperature 30°C-70°C.

4. The method for optimizing the extraction conditions of Gastrodia elata polysaccharides using response surface methodology according to claim 3, characterized in that: The specific operation of the effect of the solid-liquid ratio on the extraction rate of Gastrodia elata polysaccharide in the S2 single factor experiment is as follows: weigh the pretreated Gastrodia elata powder, mix it with water at a solid-liquid ratio of 1:15, 1:20, 1:25, 1:30 and 1:35, respectively, extract it at 60°C for 1.5h, centrifuge it, collect the supernatant, add anhydrous ethanol to the alcohol precipitation concentration, precipitate it overnight, filter it, collect the filter residue and freeze-dry it to obtain Gastrodia elata polysaccharide, and calculate the Gastrodia elata polysaccharide extraction rate.

5. The method for optimizing the extraction conditions of Gastrodia elata polysaccharides using response surface methodology according to claim 3, characterized in that: The specific operation of the effect of extraction time on the extraction rate of Gastrodia elata polysaccharide in the S2 single factor experiment is as follows: weigh the pretreated Gastrodia elata powder, mix it at a solid-liquid ratio of 1:25, extract it at 60°C for 0.5h, 1h, 1.5h, 2h, and 2.5h respectively, centrifuge it, collect the supernatant, add anhydrous ethanol to the alcohol precipitation concentration, precipitate it overnight, filter it, collect the filter residue, and freeze-dry it to obtain Gastrodia elata polysaccharide, and calculate the extraction rate of Gastrodia elata polysaccharide.

6. The method for optimizing the extraction conditions of Gastrodia elata polysaccharides using response surface methodology according to claim 3, characterized in that: The specific operation of the effect of extraction temperature on the extraction rate of Gastrodia elata polysaccharide in the S2 single factor experiment is as follows: weigh the pretreated Gastrodia elata powder, mix it at a solid-liquid ratio of 1:25, extract it at 30°C, 40°C, 50°C, 60°C, and 70°C for 1.5 hours, centrifuge it, collect the supernatant, add anhydrous ethanol to the alcohol precipitation concentration, precipitate it overnight, filter it, collect the filter residue, and freeze-dry it to obtain Gastrodia elata polysaccharide, and calculate the extraction rate of Gastrodia elata polysaccharide.

7. The method for optimizing the extraction conditions of Gastrodia elata polysaccharides using response surface methodology according to any one of claims 4 to 6, characterized in that: The centrifugal conditions are: 6000-8000 r / min, 10-20 min.

8. The method for optimizing the extraction conditions of Gastrodia elata polysaccharides using response surface methodology according to any one of claims 4 to 6, characterized in that: The alcohol precipitation concentration is 80%.

9. The method for optimizing the extraction conditions of Gastrodia elata polysaccharides using response surface methodology according to any one of claims 4 to 6, characterized in that: The alcohol precipitation temperature is 4°C.

10. The method for optimizing the extraction conditions of Gastrodia elata polysaccharides using response surface methodology according to claim 3, characterized in that: The S3 response surface experimental design also includes: evaluating the significance and goodness of fit of the model through the variance analysis method, analyzing the influence of the interaction between the three factors on the extraction rate, and determining the optimal level combination of each factor. After analysis, the optimal extraction conditions are: solid-liquid ratio 1:26, extraction time 1.75 hours, and extraction temperature 55°C.

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