Optimization method for extracting lycium barbarum polysaccharide from lycium barbarum peel residues through combination of ultrasonic assistance and alkali-water extraction

Abstract

The invention relates to the technical field of polysaccharide extraction, in particular to an optimization method for extracting lycium barbarum polysaccharide in lycium barbarum peel residues through ultrasonic assistance in combination with aqueous alkali. The optimization method provided by the invention comprises the following steps: adopting a random centroid mapping optimization method, taking water extraction time, water extraction temperature, alkali extraction time, alkali extraction temperature and a material-liquid ratio as optimization factors, determining the upper and lower limit range of each optimization factor, and carrying out a first round of random search test to obtain random optimization extraction process parameters; performing a first round of centroid inspection selection on the random optimization extraction process parameters to obtain centroid optimization extraction process parameters; and repeating the processes of the random search test and the mass center inspection selection, and sequentially carrying out a second round of random search test, a second round of mass center inspection selection, a third round of random search test and a third round of mass center inspection selection to obtain the optimal process parameters for extracting the lycium barbarum polysaccharide from the lycium barbarum peel residues by combining ultrasonic assistance with water and alkali. The optimization method is simple, convenient and effective.

Description

Technical Field

[0001] The present invention relates to the technical field of polysaccharide extraction, and particularly relates to an optimization method for ultrasonic-assisted combined water-alkali extraction of wolfberry polysaccharide from wolfberry peel residue. Background Art

[0002] Wolfberry (LB), a deciduous shrub of the genus Lycium in the Solanaceae family, also known as Tianjing, is a traditional Chinese medicinal material with a cultivation history of more than 2,300 years in China, mainly planted in Ningxia Hui Autonomous Region and other northwestern provinces. With the increasing demand for wolfberry at home and abroad, the planting area of wolfberry has been continuously expanding. In 2022, the national wolfberry planting area was approximately 1.2×10 5 hm 2 . At present, the main processed products of fresh wolfberry fruits are fruit juice, fruit vinegar, fruit wine and fermented beverages. However, about 20% - 25% of the waste is produced during the processing of fresh wolfberry fruits, which is only used as feed and fertilizer and has not been fully utilized. Long-term stacking is prone to corruption and deterioration, seriously polluting the environment. Research has found that the wolfberry peel residue produced during the juice processing still contains a large amount of alkaloids, polysaccharides, flavonoids and other chemical components, among which the polysaccharide active components that contribute most significantly to various pharmacological activities account for 5% - 8% of the dried fruits. Wolfberry polysaccharide has multiple biological effects such as antioxidant, anti-inflammatory, hypoglycemic, lipid-regulating and immune-enhancing effects.

[0003] Currently, the main extraction methods for plant polysaccharides are water extraction method, acid-base assisted extraction method, enzyme-assisted extraction method, ultrasonic-assisted extraction method and microwave-assisted extraction method. Among different extraction methods, water extraction is a traditional polysaccharide extraction method, which is green, healthy, simple to operate and low in cost, suitable for large-scale production. However, the single water extraction method requires a long treatment time and has a low extraction rate. In order to improve the extraction rate, various combined extraction methods have become a research hotspot, such as ethanol combined with ultrasonic-assisted method, ultrasonic combined with water extraction or enzyme-assisted combined with ultrasonic. In order to obtain the optimal experimental data, the above methods usually adopt orthogonal and response surface experiments to find the optimization center point relying on single-factor experiments, with a large amount of experiments and cumbersome operations. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an optimization method for ultrasonic-assisted combined water-alkali extraction of wolfberry polysaccharide from wolfberry peel residue, and the optimization method is simple, convenient and effective. In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0005] The present invention provides an optimization method for ultrasonic-assisted combined water-alkali extraction of wolfberry polysaccharide from wolfberry peel residue, comprising the following steps:

[0006] The method for water-alkali extraction of wolfberry polysaccharide from wolfberry peel residue includes: subjecting the wolfberry peel residue to water extraction with water in sequence and alkali extraction with an alkali solution;

[0007] Using the random centroid mapping optimization method, with the water extraction time, water extraction temperature, alkali extraction time, alkali extraction temperature, and solid-liquid ratio as the optimization factors, the upper and lower limit ranges of each optimization factor are determined, and the first round of random search experiments is carried out to obtain the random optimized extraction process parameters;

[0008] The random optimized extraction process parameters are subjected to the first round of centroid test selection to obtain the centroid optimized extraction process parameters;

[0009] Repeat the above processes of random search experiment and centroid test selection, and successively carry out the second round of random search experiment, the second round of centroid test selection, the third round of random search experiment, and the third round of centroid test selection to obtain the optimal process parameters for ultrasonic-assisted combined water-alkali extraction of wolfberry polysaccharide from wolfberry peel residue.

[0010] Preferably, the wolfberry peel residue is the defatted wolfberry peel residue.

[0011] Preferably, both the water extraction and alkali extraction are carried out under ultrasonic conditions.

[0012] Preferably, the alkali solution is an aqueous sodium carbonate solution with a mass concentration of 0.5%.

[0013] Preferably, after the alkali extraction is completed, it further includes successively carrying out filtration, pH adjustment, filtrate merging, rotary evaporation, alcohol precipitation, and centrifugation.

[0014] Preferably, the number of repetitions is 2 times.

[0015] Preferably, when carrying out the first round of random search experiment and the first round of centroid test selection, the search range of the water extraction time is 30 - 110 min; the search range of the water extraction temperature is 20 - 60 °C; the search range of the alkali extraction time is 20 - 80 min, the search range of the alkali extraction temperature is 25 - 45 °C, and the search range of the solid-liquid ratio is 1:(10 - 30).

[0016] Preferably, when carrying out the second round of random search experiment and the second round of centroid test selection, the search range of the water extraction time is 50 - 80 min; the search range of the water extraction temperature is 25 - 50 °C; the search range of the alkali extraction time is 40 - 60 min, the search range of the alkali extraction temperature is 30 - 40 °C, and the search range of the solid-liquid ratio is 1:(15 - 25).

[0017] Preferably, when conducting the third-round random search experiment and the third-round centroid test selection, the search range of the water extraction time is 50 - 80 min; the search range of the water extraction temperature is 25 - 50 °C; the search range of the alkali extraction time is 40 - 60 min, the search range of the alkali extraction temperature is 35 - 40 °C, and the search range of the solid-liquid ratio is 1:(15 - 20).

[0018] Preferably, the optimal water extraction time for ultrasonic-assisted combined water-alkali extraction of polysaccharides from wolfberry peel residue is 77 min, the optimal water extraction temperature is 48 °C, the optimal alkali extraction time is 47 min, the optimal alkali extraction temperature is 40 °C, and the solid-liquid ratio is 1:18.

[0019] The present invention provides an optimization method for ultrasonic-assisted combined water-alkali extraction of polysaccharides from wolfberry peel residue, comprising the following steps: The method for water-alkali extraction of polysaccharides from wolfberry peel residue includes: subjecting the wolfberry peel residue to water extraction with water in sequence and alkali extraction with an alkali solution; using the random centroid mapping optimization method, taking the water extraction time, water extraction temperature, alkali extraction time, alkali extraction temperature, and solid-liquid ratio as optimization factors, determining the upper and lower limit ranges of each optimization factor, conducting the first-round random search experiment to obtain random optimized extraction process parameters; conducting the first-round centroid test selection on the random optimized extraction process parameters to obtain centroid-optimized extraction process parameters; repeating the above processes of random search experiment and centroid test selection, successively conducting the second-round random search experiment, the second-round centroid test selection, the third-round random search experiment, and the third-round centroid test selection to obtain the optimal process parameters for ultrasonic-assisted combined water-alkali extraction of polysaccharides from wolfberry peel residue. Since polysaccharides and other substances in by-products (such as flavonoids) are different bioactive substances, their chemical properties and forms of existence in plants are different, so the extraction methods are also different. Flavonoid compounds usually exist in the form of glycosides in tissues such as the flowers, leaves, and fruits of plants, while in hard xylem tissues, they mostly exist in the form of free aglycones. When extracting flavonoid compounds, it is necessary to pay attention to avoiding the occurrence of hydrolysis reactions, and the common extraction methods are mainly solvent extraction. Polysaccharides are a class of macromolecular compounds and usually exist in the form of polysaccharide glycosides in plants. When extracting polysaccharides, it is necessary to pay attention to maintaining the integrity of their molecular structure. Therefore, the present invention selects specific extraction methods and specific extraction conditions as optimization factors, obtains the optimal process parameters, and the polysaccharide extraction rate from wolfberry peel residue using the optimal process parameters reaches more than 10%. Description of the Drawings

[0020] Figure 1 It is a mapping diagram of the optimization conditions for the first-round random centroid mapping experiment and the first-round centroid test selection in Example 1;

[0021] Figure 2Optimization condition mapping diagram selected for the second-round random centroid mapping test and the second-round centroid test in Example 1;

[0022] Figure 3 Optimization condition mapping diagram selected for the third-round random centroid mapping test and the third-round centroid test in Example 1;

[0023] Figure 4 Ultraviolet spectrum diagram of the wolfberry polysaccharide extracted under the optimal conditions in Example 1;

[0024] Figure 5 Fourier transform infrared spectrum diagram of the wolfberry polysaccharide extracted under the optimal conditions in Example 1;

[0025] Figure 6 Antioxidant curve of the wolfberry polysaccharide extracted under the optimal conditions in Example 1 against DPPH free radicals;

[0026] Figure 7 Antioxidant curve of the wolfberry polysaccharide extracted under the optimal conditions in Example 1 against ABTS free radicals;

[0027] Figure 8 Total antioxidant capacity curve of the wolfberry polysaccharide extracted under the optimal conditions in Example 1. Detailed implementation manners

[0028] The present invention provides an optimization method for ultrasonic-assisted combined water-alkali extraction of wolfberry polysaccharide from wolfberry peel residue, comprising the following steps:

[0029] The method for water-alkali extraction of wolfberry polysaccharide from wolfberry peel residue includes: subjecting the wolfberry peel residue to water extraction with water in sequence and alkali extraction with an alkali solution;

[0030] Adopting the random centroid mapping optimization method, using water extraction time, water extraction temperature, alkali extraction time, alkali extraction temperature and solid-liquid ratio as optimization factors, determining the upper and lower limit ranges of each optimization factor, conducting the first-round random search test, and obtaining the random optimization extraction process parameters;

[0031] Conducting the first-round centroid test selection on the random optimization extraction process parameters to obtain the centroid optimization extraction process parameters;

[0032] Repeating the above processes of random search test and centroid test selection, successively conducting the second-round random search test, the second-round centroid test selection, the third-round random search test and the third-round centroid test selection to obtain the optimal process parameters for ultrasonic-assisted combined water-alkali extraction of wolfberry polysaccharide from wolfberry peel residue.

[0033] In the present invention, without special instructions, all preparation raw materials are commercially available products well-known to those skilled in the art.

[0034] The method for extracting wolfberry polysaccharide from wolfberry pomace by using water and alkali in the present invention includes: subjecting the wolfberry pomace to water extraction with water in sequence and alkali extraction with an alkali solution.

[0035] Before carrying out the water extraction, the present invention preferably further includes successively pulverizing, sieving and defatting the wolfberry pomace; in the present invention, the sieving is preferably through a 40-mesh sieve; the present invention has no special limitation on the processes of pulverizing and defatting, and any process well-known to those skilled in the art can be used.

[0036] In the present invention, the water extraction preferably uses pure water; the water extraction is preferably carried out under ultrasonic conditions, and the present invention has no special limitation on the ultrasonic process, and any process well-known to those skilled in the art can be used.

[0037] After the water extraction is completed, the present invention preferably further includes filtration, and the present invention has no special limitation on the filtration process, and any process well-known to those skilled in the art can be used; the filter residue obtained after filtration is preferably further subjected to alkali extraction.

[0038] In the present invention, the alkali solution used for alkali extraction is preferably an aqueous sodium carbonate solution with a mass concentration of 0.5%. In the present invention, the alkali extraction is preferably carried out under ultrasonic conditions, and the present invention has no special limitation on the ultrasonic process, and any process well-known to those skilled in the art can be used.

[0039] After the alkali extraction is completed, the present invention preferably further includes successively carrying out filtration, adjusting the pH value, combining the filtrates, rotary evaporation, alcohol precipitation and centrifugation. The present invention has no special limitation on the filtration process, and any process well-known to those skilled in the art can be used. The present invention has no special limitation on the process of adjusting the pH value, and any process well-known to those skilled in the art can be used, and it is only necessary to ensure that the adjusted pH value is within the range of 5-8. The present invention has no special limitation on the processes of combining the filtrates, rotary evaporation, alcohol precipitation and centrifugation, and any process well-known to those skilled in the art can be used.

[0040] The optimization method in the present invention adopts the random centroid mapping optimization method, uses the water extraction time, water extraction temperature, alkali extraction time, alkali extraction temperature and solid-liquid ratio as optimization factors, determines the upper and lower limit ranges of each optimization factor, conducts the first-round random search experiment, and obtains the randomly optimized extraction process parameters.

[0041] In the present invention, when conducting the first-round random search test and the first-round centroid test selection, the search range of the water extraction time is preferably 30 to 110 min; the search range of the water extraction temperature is preferably 20 to 60 °C; the search range of the alkali extraction time is preferably 20 to 80 min, the search range of the alkali extraction temperature is preferably 25 to 45 °C, and the search range of the solid-liquid ratio is preferably 1:(10 to 30).

[0042] In the present invention, the process of the first-round random search test is preferably to input the search ranges of the water extraction time, water extraction temperature, alkali extraction time, alkali extraction temperature, and solid-liquid ratio into the Random-Centroid Optimization program, run the program, and the program will randomly design test conditions to conduct the first-round random search test.

[0043] After obtaining the randomly optimized extraction process parameters, the present invention conducts the first-round centroid test selection on the randomly optimized extraction process parameters to obtain the centroid-optimized extraction process parameters.

[0044] In the present invention, the first-round centroid test selection uses the extraction rate of crude polysaccharide as the evaluation index, and inputs the extraction rate results of the crude polysaccharide obtained from the above-mentioned randomly designed test conditions into their respective test groups for centroid test selection.

[0045] After obtaining the centroid-optimized extraction process parameters, the present invention repeats the above processes of random search test and centroid test selection, and successively conducts the second-round random search test, the second-round centroid test selection, the third-round random search test, and the third-round centroid test selection to obtain the optimal process parameters for ultrasonic-assisted combined water-alkali extraction of wolfberry polysaccharide from wolfberry peel residue.

[0046] In the present invention, the number of repetitions is preferably 2 times.

[0047] In the present invention, the centroid-optimized extraction process parameters obtained in the previous round are used as a reference for determining the search ranges of each optimization factor when conducting the random search test and centroid test selection in the next round.

[0048] In the present invention, when conducting the second-round random search test and the second-round centroid test selection, the search range of the water extraction time is preferably 50 to 80 min; the search range of the water extraction temperature is preferably 25 to 50 °C; the search range of the alkali extraction time is preferably 40 to 60 min, the search range of the alkali extraction temperature is preferably 30 to 40 °C, and the search range of the solid-liquid ratio is preferably 1:(15 to 25).

[0049] In the present invention, when performing the third-round random search test and the third-round centroid test selection, the search range of the water extraction time is preferably 50 to 80 min; the search range of the water extraction temperature is preferably 25 to 50 °C; the search range of the alkali extraction time is preferably 40 to 60 min, the search range of the alkali extraction temperature is preferably 35 to 40 °C, and the search range of the solid-liquid ratio is preferably 1:(15 to 20).

[0050] In the present invention, the processes of the second-round random search test, the second-round centroid test selection, the third-round random search test, and the third-round centroid test selection preferably refer to the processes of the first-round random search test and the first-round centroid test selection. Details are not described herein again.

[0051] In the present invention, the optimal water extraction time for ultrasonic-assisted combined water-alkali extraction of wolfberry polysaccharide from wolfberry peel residue is preferably 77 min, the optimal water extraction temperature is preferably 48 °C, the optimal alkali extraction time is preferably 47 min, the optimal alkali extraction temperature is preferably 40 °C, and the solid-liquid ratio is preferably 1:18.

[0052] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0053] Example 1

[0054] The wolfberry peel residue is successively pulverized, sieved through a 40-mesh sieve, and defatted to obtain defatted wolfberry peel residue powder;

[0055] 10.00 g of the defatted wolfberry peel residue powder is added to pure water, and after water extraction under ultrasonic conditions, filtration is carried out, and the filtrate is collected. The obtained filter residue is added to a sodium carbonate solution with a mass concentration of 0.5%, filtered under ultrasonic conditions, the pH value is adjusted to 7.0, the filtrates are combined, rotary evaporation and concentration are carried out, alcohol precipitation is carried out for 12 h, and centrifugation is carried out to obtain crude polysaccharide;

[0056] The upper and lower limit ranges of the factors to be optimized shown in Table 1 are respectively input into the software;

[0057] Table 1 Upper and lower limit ranges of the factors to be optimized in the first round

[0058]

[0059] The software will randomly design the test conditions (a total of 10 groups, as shown in Table 2), and conduct the first-round random centroid mapping test according to the above-mentioned crude polysaccharide extraction process (the test results, such as the crude polysaccharide and the extraction rate of the crude polysaccharide, are shown in Table 2) and the first-round centroid test selection (the software judges the trend range to obtain the centroid-optimized extraction process parameters in the first round, as shown in Table 2);

[0060] Table 2 The test conditions and results of the first-round random centroid mapping test, and the results of the first-round centroid test selection

[0061]

[0062]

[0063] Input the results of the first-round random centroid mapping test and the first-round centroid test selection into the RCO program to obtain the optimized condition mapping diagram in the first round, as Figure 1 shown, where each optimization factor corresponds to a mapping optimization diagram, and the best value of the optimization factor is indicated at the abscissa. It can be seen from Figure 1 that the best optimized process parameters are: water extraction time is 73 min, water extraction temperature is 29 °C, alkali extraction time is 45 min, alkali extraction temperature is 37 °C, and solid-liquid ratio is 1:17; however Figure 1 the mapping results are relatively scattered, so the second-round random centroid mapping test and the second-round centroid test selection are carried out;

[0064] Input the upper and lower limit ranges of the factors to be optimized in the second round (as shown in Table 3) into the software respectively;

[0065] Table 3 The upper and lower limit ranges of the factors to be optimized in the second round

[0066]

[0067] The software will randomly design the test conditions (a total of 10 groups, as shown in Table 4), and conduct the second-round random centroid mapping test according to the above-mentioned crude polysaccharide extraction process (the test results, such as the crude polysaccharide and the extraction rate of the crude polysaccharide, are shown in Table 4) and the second-round centroid test selection (the software judges the trend range to obtain the centroid-optimized extraction process parameters in the first round, as shown in Table 4);

[0068] Table 4 The test conditions and results of the second-round random centroid mapping test, and the results of the second-round centroid test selection

[0069]

[0070]

[0071] Input the results of the second-round random centroid mapping test and the first-round centroid test selection into the RCO program to obtain the optimized condition mapping diagram in the second round, asFigure 2 as shown, where each optimization factor corresponds to a mapping optimization diagram, and the value indicated by the abscissa is the optimal value of this optimization factor. From Figure 2 it can be seen that the optimal optimization process parameters are: the water extraction time is 77 min, the water extraction temperature is 48 °C, the alkali extraction time is 47 min, the alkali extraction temperature is 40 °C, and the solid-liquid ratio is 1:18; it should be noted that the extraction rate of crude polysaccharides is generally higher than the experimental results of the first round. The optimization points, curves, and straight lines of the water extraction temperature, alkali extraction temperature, and solid-liquid ratio are concentrated, while the optimization points, curves, and straight lines of the water extraction time and alkali extraction time are more dispersed. Therefore, based on the experimental results of the second round, the upper and lower limit ranges of the factors to be optimized in the third round are input (as shown in Table 5);

[0072] Table 5 Upper and lower limit ranges of the factors to be optimized in the third round

[0073]

[0074] The software will randomly design the experimental conditions (a total of 10 groups, as shown in Table 6), and conduct the second-round random centroid mapping experiment according to the above-mentioned extraction process of crude polysaccharides (the experimental results, such as the crude polysaccharides and the extraction rate of crude polysaccharides, are shown in Table 6) and the second-round centroid test selection (the software judges the trend range to obtain the centroid optimization extraction process parameters in the first round, as shown in Table 6);

[0075] Table 6 Experimental conditions and results of the third-round random centroid mapping, and results of the third-round centroid test selection

[0076]

[0077] Input the results of the third-round random centroid mapping experiment and the third-round centroid test selection into the RCO program to obtain the optimization condition mapping diagram of the third round, as Figure 3 shown, where each optimization factor corresponds to a mapping optimization diagram, and the value indicated by the abscissa is the optimal value of this optimization factor. From Figure 3 it can be seen that the optimal optimization process parameters are: the water extraction time is 77 min, the water extraction temperature is 48 °C, the alkali extraction time is 47 min, the alkali extraction temperature is 40 °C, and the solid-liquid ratio is 1:18; it is more concentrated than the optimization points, curves, and straight lines in the first and second rounds.

[0078] Extract crude polysaccharides (wolfberry polysaccharides) according to the above condition parameters of water extraction time of 77 min, water extraction temperature of 48 °C, alkali extraction time of 47 min, alkali extraction temperature of 40 °C, and solid-liquid ratio of 1:18;

[0079] Conduct ultraviolet spectrum analysis on the wolfberry polysaccharides, where Figure 4 is the ultraviolet spectrum diagram of the wolfberry polysaccharides. From Figure 4It can be seen that the wolfberry polysaccharide has no absorption peaks at 260 nm and 280 nm, indicating that the wolfberry polysaccharide prepared under the above conditions has high purity and almost no substances such as polypeptides, nucleic acids, and proteins;

[0080] Figure 5 is the Fourier transform infrared spectrum of the wolfberry polysaccharide, from Figure 5 it can be seen that the peaks at 3387 cm -1 and 3297 cm -1 are characteristic spectral bands of -OH stretching vibration. The peak at 2960 cm -1 represents C-H stretching vibration caused by CH, CH 2 , CH 3 . The strong absorption peak at 1650 cm -1 and the weak absorption peak at 1743 cm -1 belong to the stretching vibrations of esterified (COO-) and free (COO-) C=O. The absorption peak at 1550 cm -1 is the N-H deformation amplitude. The peak at 1400 cm -1 may be related to the bending of CH 2 OH and the stretching of -CH 3 CO. The strong absorption peak obtained at 1098 cm -1 usually represents the glycosidic bond connection between sugar units. The characteristic peak at 626 cm -1 indicates the presence of mannose and rhamnose in the wolfberry polysaccharide.

[0081] Figure 6 is the antioxidant curve of the wolfberry polysaccharide against DPPH radicals. From Figure 5 it can be seen that the scavenging rate of the wolfberry polysaccharide against DPPH radicals gradually increases with the increase of the mass concentration, showing an obvious dose-effect relationship. In the concentration range of 3 mg / mL, the scavenging ability against DPPH radicals rapidly increases with the increase of the concentration. When the concentration is 6 mg / mL, the scavenging ability reaches 93.92%;

[0082] Figure 7 is the antioxidant curve of the wolfberry polysaccharide against ABTS radicals. From Figure 6 it can be seen that the scavenging ability of ABTS radicals and the concentration of wolfberry polysaccharide show a dose-effect relationship within a certain concentration range. With the increase of the concentration of wolfberry polysaccharide, the scavenging ability of wolfberry polysaccharide against ABTS radicals gradually increases. When the concentration is 6 mg / mL, the scavenging ability of ABTS radicals is stronger, and the scavenging rate reaches 91.68%. This is mainly because the wolfberry polysaccharide exerts its antioxidant effect through an electron transfer mechanism. In addition, the imbalance between the generation and consumption of reactive oxygen species leads to oxidative stress, and normalizing the generation of reactive oxygen species can play an antioxidant role;

[0083] Figure 8 is the total antioxidant capacity curve of the wolfberry polysaccharide, from Figure 7 it can be seen that, similar to the scavenging of DPPH free radicals and ABTS free radicals, there is a dose-effect relationship between the concentration of wolfberry polysaccharide and the total antioxidant capacity within a certain concentration range. With the increase of the concentration, the total antioxidant capacity increases significantly. When the concentration is 6 mg / mL, the total antioxidant capacity is relatively strong, and the scavenging rate reaches 6.11 μmol / g.

[0084] The above are only the preferred embodiments of the present invention, and do not impose any formal limitations on the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An optimization method for ultrasonic-assisted combined water-alkali extraction of Lycium barbarum polysaccharides from Lycium barbarum peel residue, characterized in that: The following steps are involved: The method for extracting wolfberry polysaccharide from wolfberry peel residue with water and alkali solution comprises: extracting the wolfberry peel residue with water and alkali solution in sequence; The random centroid mapping optimization method was adopted, with water extraction time, water extraction temperature, alkali extraction time, alkali extraction temperature and material-liquid ratio as optimization factors, and the upper and lower limits of each optimization factor were determined. The first round of random search experiments were carried out to obtain the random optimization extraction process parameters. Performing a first round of centroid test selection on the randomly optimized extraction process parameters to obtain centroid optimized extraction process parameters; The above-mentioned random search test and centroid test selection process are repeated, and the second round of random search test, the second round of centroid test selection, the third round of random search test and the third round of centroid test selection are carried out in sequence to obtain the optimal process parameters for the ultrasonic-assisted combined water-alkali extraction of wolfberry polysaccharides from wolfberry peel residue.

2. The optimization method according to claim 1, characterized in that: The wolfberry peel residue is the wolfberry peel residue after fat removal.

3. The optimization method according to claim 1 or 2, characterized in that: The water extraction and alkali extraction are both carried out under ultrasonic conditions.

4. The optimization method according to claim 3, characterized in that: The alkali solution is a sodium carbonate aqueous solution with a mass concentration of 0.5%.

5. The optimization method according to claim 4, characterized in that: After the alkaline extraction is completed, the steps include filtering, adjusting the pH value, combining the filtrate, rotary evaporation, alcohol precipitation and centrifugation in sequence.

6. The optimization method according to claim 1, characterized in that: The number of repetitions is 2 times.

7. The optimization method according to claim 6, characterized in that: When conducting the first round of random search test and the first round of centroid test selection, the water extraction time is 30 to 110 minutes; the water extraction temperature is 20 to 60°C; the alkali extraction time is 20 to 80 minutes, the alkali extraction temperature is 25 to 45°C, and the solid-liquid ratio is 1:(10 to 30).

8. The optimization method according to claim 7, characterized in that: When conducting the second round of random search tests and the second round of centroid test selection, the search range of the water extraction time is 50 to 80 min; the search range of the water extraction temperature is 25 to 50°C; the search range of the alkali extraction time is 40 to 60 min, the search range of the alkali extraction temperature is 30 to 40°C, and the search range of the solid-liquid ratio is 1:(15 to 25).

9. The optimization method according to claim 8, characterized in that: When conducting the third round of random search test and the third round of centroid test selection, the search range of the water extraction time is 50 to 80 min; the search range of the water extraction temperature is 25 to 50° C.; the search range of the alkali extraction time is 40 to 60 min, the search range of the alkali extraction temperature is 35 to 40° C., and the search range of the solid-liquid ratio is 1:(15 to 20).

10. The optimization method according to claim 9, characterized in that: The optimal water extraction time for the ultrasonic-assisted combined water-alkali extraction of wolfberry polysaccharides from wolfberry peel residue is 77 minutes, the optimal water extraction temperature is 48°C, the optimal alkali extraction time is 47 minutes, the optimal alkali extraction temperature is 40°C, and the solid-liquid ratio is 1:18.

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