Preparation process of hermetia illucens polypeptide and anti-oxidation application of hermetia illucens polypeptide

Abstract

The invention provides a preparation process and antioxidant application of hermetia illucens polypeptide. The preparation process comprises the steps of cleaning and disinfection, crushing, desugaring, degreasing, enzymolysis, separation and purification and the like. The method comprises the following steps: washing hermetia illucens larvae with clear water, soaking in saline water and carrying out ultraviolet radiation treatment; then, adopting a superfine grinding technology to obtain larva powder, and performing desugaring treatment through two times of centrifugation; then, absolute ethyl alcohol and normal hexane in a specific proportion are used for degreasing the precipitate under a certain condition; adding a compound enzyme into the degreased hermetia illucens powder, carrying out enzymolysis under the assistance of sweep-frequency pulse ultrasound, and finally, carrying out ultrafiltration treatment to obtain hermetia illucens polypeptide with the molecular weight of less than or equal to 1kDa, the polypeptide prepared by the process has antioxidant activity, can be applied to preparation of animal feeds and organic fertilizers, and is especially suitable for aquatic animals and mammals. The hermetia illucens polypeptide disclosed by the invention is simple and efficient in preparation process, and the obtained polypeptide has remarkable oxidation resistance and wide application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of biological antimicrobial peptides, and in particular to a preparation process of a black soldier fly polypeptide and an antioxidant application thereof. Background Art

[0002] With the continuous development of biotechnology and the in-depth exploration of natural resources, insect protein and its derivatives as new biological resources have gradually attracted widespread attention from the scientific research and industrial communities. As an environmentally friendly insect, the black soldier fly (Hermetia illucens) is regarded as one of the most promising biological resources because of its rapid growth, low breeding cost, high protein content and rich in various bioactive substances. Among them, black soldier fly polypeptide, as an important biologically active component in the black soldier fly, has multiple biological functions such as antioxidant, antibacterial and anti-inflammatory, showing broad application prospects in the fields of medicine, food, feed and agriculture.

[0003] Traditional methods for extracting black soldier fly polypeptides mostly rely on simple physical crushing and solvent extraction. Although these methods are easy to operate, they often cannot effectively remove impurities such as sugars and lipids in the black soldier fly larvae, resulting in low purity of the extracted black soldier fly polypeptides and affected biological activity. At the same time, due to the lack of effective auxiliary means in the extraction process, the extraction efficiency is also relatively low, which is difficult to meet the needs of large-scale production. Summary of the invention

[0004] In view of this, the present invention provides a preparation process of a black soldier fly polypeptide and its antioxidant use to solve the above problems.

[0005] The technical solution of the present invention is achieved as follows: A process for preparing a black soldier fly polypeptide comprises the following steps:

[0006] S1. Cleaning and disinfection: Select healthy, disease-free, well-grown black soldier fly larvae, rinse them with clean water for 3-5 times, soak them in 5%-10% saline for 20-30 minutes, and finally irradiate them with ultraviolet light for 15-25 minutes;

[0007] S2, crushing: crushing the treated black soldier fly larvae, using ultrafine crushing technology to crush the black soldier fly larvae to a particle size of 10-50 μm, to obtain black soldier fly larvae powder;

[0008] S3, desugaring: take the black soldier fly larvae powder and add physiological saline to stir and homogenize, place in a centrifuge, centrifuge at 7-10°C, 700-900×g for 10-20 min, discard the supernatant, take precipitate I and continue to add physiological saline, centrifuge at 4-6°C, 10000-13000×g for 30-50 min, aspirate the supernatant, take precipitate II, and set aside;

[0009] S4, defatting: put the precipitate II into an extraction kettle, introduce an organic solvent into the extraction kettle, the mass volume ratio of the precipitate II to the organic solvent is 5-10:50 g / mL, and the organic solvent is anhydrous ethanol and n-hexane in a volume ratio of 2-5:8-10, extract it at 30-50°C and 15-30MPa for 2-4 times, each time for 1-3h, combine the extracts, separate, and obtain defatted insect powder and insect fat;

[0010] S5, enzymatic hydrolysis: adding compound enzyme to the defatted insect powder, the compound enzyme addition amount is 0.5-1.5% of the mass of the insect powder, enzymatic hydrolysis for 3-4 hours at pH 6.0-7.0 and temperature 35-37°C, and applying sweep pulse ultrasound to assist enzymatic hydrolysis;

[0011] S6. Separation and purification: The above enzymatic hydrolysate is subjected to ultrafiltration treatment at a flow rate of 1-5 m / s to obtain a black soldier fly polypeptide with a molecular weight of ≤1 kDa.

[0012] Furthermore, the ultraviolet irradiation intensity of S1 is 1000-5000 μW / cm2.

[0013] Furthermore, the mass volume ratio of the black soldier fly larvae powder and physiological saline in S3 is 0.3-0.8:20 g / mL.

[0014] Furthermore, the mass volume ratio g / mL of the S3 precipitate I and the physiological saline is 0.9-1.3:30.

[0015] Furthermore, the complex enzyme of S5 is chitinase, protease and glycoside hydrolase in a mass ratio of (5.8-9.5):(2.6-3.5):(4.5-8.2), and the enzyme activity is greater than 10000 U / g.

[0016] Furthermore, in the S5, the ultrasonic frequency is 32-50kHz, the ultrasonic power is 50-300W, and the sweep frequency range is 20-100kHz.

[0017] Furthermore, the ultrafiltration pressure in S6 is 0.1-0.5 MPa and the temperature is 20-25°C.

[0018] Furthermore, the preparation process of the black soldier fly polypeptide provides the antioxidant use of the black soldier fly polypeptide.

[0019] Furthermore, the antioxidant use is used in preparing animal feed or organic fertilizer.

[0020] Furthermore, the animals include aquatic animals or mammals.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) Improve product quality

[0023] Through multiple steps of cleaning, disinfection, desugaring, degreasing, etc., impurities in black soldier fly larvae, especially sugars and lipids, are effectively removed. Subsequent enzymatic hydrolysis and ultrafiltration further ensure the high purity of black soldier fly polypeptides in the final product. Peptide products with a molecular weight of ≤1kDa have high purity and can better exert their specific biological activity; after removing impurities, the stability of the polypeptide is enhanced, and it is not easy to deteriorate during storage and transportation. It can better maintain its antioxidant properties and extend the shelf life of the product.

[0024] (2) Optimize the preparation process

[0025] Ultrafine grinding technology crushes the larvae to a specific particle size, increasing the exposure area of ​​the active ingredients and facilitating subsequent processing. The reasonable ratio of compound enzymes and sweep pulse ultrasound-assisted enzymolysis greatly improve the efficiency of enzymolysis and significantly increase the extraction rate of polypeptides. Ultrafiltration treatment accurately controls the molecular weight range of the product, ensuring the consistency and high quality of the product.

[0026] (3) Expanding application areas

[0027] The prepared black soldier fly polypeptide is rich in various antioxidant ingredients, can effectively scavenge free radicals, inhibit oxidation reactions, and exhibit excellent antioxidant properties. It can not only be used to prepare high-value-added animal feed, improve the antioxidant capacity and growth performance of animals, but also can be used as an organic fertilizer additive to promote plant growth and improve the soil environment. It has broad market prospects and application value. DETAILED DESCRIPTION

[0028] In order to better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0029] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0030] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can be obtained from commercial sources.

[0031] Example 1

[0032] A preparation process of a black soldier fly polypeptide comprises the following steps:

[0033] S1. Cleaning and disinfection: Select healthy, disease-free, well-grown black soldier fly larvae, rinse them three times with clean water, soak them in 5% saline for 20 minutes, and finally irradiate them with ultraviolet light for 15 minutes at an intensity of 1000 μW / cm2;

[0034] S2, crushing: crushing the treated black soldier fly larvae, using ultrafine crushing technology to crush the black soldier fly larvae to a particle size of 10 μm to obtain black soldier fly larvae powder;

[0035] S3, desugaring: take the above black soldier fly larvae powder and add physiological saline to stir and homogenize, the mass volume ratio of black soldier fly larvae powder and physiological saline is 0.3:20 g / mL, place in a centrifuge, centrifuge at 7°C, 700×g for 10 min, discard the supernatant, take precipitate I and continue to add physiological saline, the mass volume ratio of precipitate I and physiological saline is 0.9:30 g / mL, centrifuge at 4°C, 10000×g for 30-50 min, aspirate the supernatant, take precipitate II, and set aside;

[0036] S4, defatting: put the precipitate II into an extraction kettle, introduce an organic solvent into the extraction kettle, the mass volume ratio of the precipitate II to the organic solvent is 5:50 g / mL, the organic solvent is anhydrous ethanol and n-hexane in a volume ratio of 2:8, extract it twice at 30°C and 15MPa, each time for 1h, combine the extracts, separate, and obtain defatted insect powder and insect fat;

[0037] S5, enzymatic hydrolysis: adding a composite enzyme to the defatted insect powder, wherein the composite enzyme is chitinase, protease and glycoside hydrolase in a mass ratio of 5.8:2.6:4.5, and the enzyme activity is greater than 10000U / g, and the amount of composite enzyme added is 0.5% of the mass of the insect powder, and enzymatic hydrolysis is performed at a pH value of 6.0 and a temperature of 35°C for 3h, and sweep pulse ultrasound is applied to assist enzymatic hydrolysis, with an ultrasonic frequency of 32kHz, an ultrasonic power of 50W, and a sweep frequency range of 20kHz;

[0038] S6. Separation and purification: The above enzymatic hydrolysate is subjected to ultrafiltration treatment at an ultrafiltration pressure of 0.1 MPa, a temperature of 20° C., and a flow rate of 1 m / s to obtain a black soldier fly polypeptide with a molecular weight of ≤1 kDa.

[0039] Example 2

[0040] A preparation process of a black soldier fly polypeptide comprises the following steps:

[0041] S1. Cleaning and disinfection: Select healthy, disease-free, and well-grown black soldier fly larvae, rinse them with clean water for 5 times, soak them in 10% saline for 30 minutes, and finally irradiate them with ultraviolet light for 25 minutes at an intensity of 5000 μW / cm 2 ;

[0042] S2, crushing: crushing the treated black soldier fly larvae, using ultrafine crushing technology to crush the black soldier fly larvae to a particle size of 50 μm to obtain black soldier fly larvae powder;

[0043] S3, desugaring: take the above black soldier fly larvae powder and add physiological saline to stir and homogenize, the mass volume ratio of black soldier fly larvae powder and physiological saline is 0.8:20 g / mL, place in a centrifuge, centrifuge at 10°C, 900×g for 20 min, discard the supernatant, take precipitate I and continue to add physiological saline, the mass volume ratio of precipitate I and physiological saline is 1.3:30 g / mL, centrifuge at 6°C, 13000×g for 50 min, aspirate the supernatant, take precipitate II, and set aside;

[0044] S4, defatting: put the precipitate II into an extraction kettle, introduce an organic solvent into the extraction kettle, the mass volume ratio of the precipitate II to the organic solvent is 10:50 g / mL, the organic solvent is anhydrous ethanol and n-hexane in a volume ratio of 5:10, extract it 4 times at 50°C and 30MPa, each time for 3h, combine the extracts, separate, and obtain defatted insect powder and insect fat;

[0045] S5, enzymatic hydrolysis: adding a composite enzyme to the defatted insect powder, wherein the composite enzyme is chitinase, protease and glycoside hydrolase in a mass ratio of 9.5:3.5:8.2, and the enzyme activity is greater than 10000U / g, and the amount of composite enzyme added is 1.5% of the mass of the insect powder, and enzymatic hydrolysis is performed at a pH value of 7.0 and a temperature of 37°C for 4 hours, while applying swept frequency pulse ultrasound to assist enzymatic hydrolysis, with an ultrasonic frequency of 50kHz, an ultrasonic power of 300W, and a sweep frequency range of 100kHz;

[0046] S6. Separation and purification: The above enzymatic hydrolysate is subjected to ultrafiltration treatment at an ultrafiltration pressure of 0.5 MPa, a temperature of 25° C., and a flow rate of 5 m / s to obtain a black soldier fly polypeptide with a molecular weight of ≤1 kDa.

[0047] Example 3

[0048] A preparation process of a black soldier fly polypeptide comprises the following steps:

[0049] S1. Cleaning and disinfection: Select healthy, disease-free, well-grown black soldier fly larvae, rinse them with clean water for 4 times, soak them in 8% saline for 25 minutes, and finally irradiate them with ultraviolet light for 20 minutes at an intensity of 3000 μW / cm2;

[0050] S2, crushing: crushing the treated black soldier fly larvae, using ultrafine crushing technology to crush the black soldier fly larvae to a particle size of 30 μm to obtain black soldier fly larvae powder;

[0051] S3, desugaring: take the above black soldier fly larvae powder and add physiological saline to stir and homogenize, the mass volume ratio of black soldier fly larvae powder to physiological saline is 0.5:20 g / mL, place in a centrifuge, centrifuge at 8°C, 800×g for 15 min, discard the supernatant, take precipitate I and continue to add physiological saline, the mass volume ratio of precipitate I to physiological saline is 1.0:30 g / mL, centrifuge at 5°C, 12000×g for 40 min, aspirate the supernatant, take precipitate II, and set aside;

[0052] S4, defatting: put the precipitate II into an extraction kettle, introduce an organic solvent into the extraction kettle, the mass volume ratio of the precipitate II to the organic solvent is 8:50 g / mL, the organic solvent is anhydrous ethanol and n-hexane in a volume ratio of 3:9, extract it 3 times at 40°C and 25MPa, each time for 2h, combine the extracts, separate, and obtain defatted insect powder and insect fat;

[0053] S5, enzymatic hydrolysis: adding a composite enzyme to the defatted insect powder, wherein the composite enzyme is chitinase, protease and glycoside hydrolase in a mass ratio of 7.5:2.8:6.5, and the enzyme activity is greater than 10000U / g, and the amount of composite enzyme added is 1.0% of the mass of the insect powder, and enzymatic hydrolysis is performed at a pH value of 6.5 and a temperature of 36°C for 4h, and sweep pulse ultrasound is applied to assist enzymatic hydrolysis, with an ultrasonic frequency of 45kHz, an ultrasonic power of 150W, and a sweep frequency range of 60kHz;

[0054] S6. Separation and purification: The above enzymatic hydrolysate is subjected to ultrafiltration treatment at an ultrafiltration pressure of 0.3 MPa, a temperature of 23° C., and a flow rate of 3 m / s to obtain a black soldier fly polypeptide with a molecular weight of ≤1 kDa.

[0055] Comparative Example 1

[0056] The difference between this comparative example and Example 3 is that no desugaring step is performed in the preparation process of the black soldier fly polypeptide.

[0057] Comparative Example 2

[0058] The difference between this comparative example and Example 3 is that in the preparation process of the black soldier fly polypeptide, the composite enzyme is chitinase, protease and cellulase in a mass ratio of 9.5:3.5:8.2.

[0059] Comparative Example 3

[0060] The difference between this comparative example and Example 3 is that no defatting step is performed in the preparation process of the black soldier fly polypeptide.

[0061] Comparative Example 4

[0062] The difference between this comparative example and Example 3 is that in the preparation process of the black soldier fly polypeptide, no frequency-sweeping pulsed ultrasound assistance is applied during the enzymatic hydrolysis process.

[0063] Test Example 1 - Determination of impurity content

[0064] 1. Determination of sugar removal rate: The black soldier fly polypeptides extracted in the above Examples 1-3 and Comparative Examples 1-2 were used to determine the sugar content in the samples before and after extraction using anthrone colorimetry or phenol-sulfuric acid method, and the removal effect was evaluated by the change in content;

[0065] Sugar removal rate = (initial sugar content - sugar content after treatment) / initial sugar content × 100%.

[0066] 2. Determination of lipid removal rate: The black soldier fly polypeptides extracted in the above Examples 1-3 and Comparative Example 3 were subjected to Soxhlet extraction to determine the lipid content in the samples before and after extraction, and the degreasing effect was evaluated by comparing the changes in lipid content before and after extraction;

[0067] Lipid removal rate = (initial lipid content - lipid content after treatment) / initial lipid content × 100%.

[0068] Table 1:

[0069] Sugar removal rate% Lipid removal rate % Example 1 82.5 71.9 Example 2 83.1 72.5 Example 3 85.5 78.2 Comparative Example 1 43.8 - Comparative Example 2 65.2 - Comparative Example 3 - 52.9

[0070] Test Example 2-Quality Index Determination

[0071] 1. Determination of extraction rate:

[0072] 1. Raw material preparation: Weigh the black soldier fly raw materials obtained in Examples 1-3 and Comparative Examples 1-4, and record their mass (M 0 );

[0073] 2. Determination of polypeptide content: The polypeptide content in the treated extract was determined by ultraviolet spectrophotometry (M 1 );

[0074] Extraction rate (%) = (M 1 / M 0 )×100.

[0075] 2. Purity determination:

[0076] The purity of the peptide was analyzed by high performance liquid chromatography (HPLC), and the purity was evaluated by the distribution of chromatographic peaks;

[0077] The high performance liquid chromatography (HPLC) was set up as follows:

[0078] 1. Chromatographic column: reverse phase 250mm×4.6mm C18 column;

[0079] 2. Mobile phase: water and acetonitrile;

[0080] 3. Flow rate: 1.5 mL / min;

[0081] 4. Detection wavelength: 214nm;

[0082] 5. Column temperature: 25±2℃;

[0083] 6. Purity calculation:

[0084]

[0085] Table 2:

[0086] Extraction rate (%) purity(%) Example 1 72.5 96.1 Example 2 74.9 95.8 Example 3 75.8 97.9 Comparative Example 1 62.2 72.4 Comparative Example 2 65.7 75.1 Comparative Example 3 67.1 73.8 Comparative Example 4 59.8 62.4

[0087] The above results show that, compared with Comparative Examples 1 and 2, Example 3 can effectively remove soluble impurities, excess sugars and non-target components with small molecular weight in the black soldier fly larvae powder through two centrifugation operations under different conditions. Removing sugar impurities enables the composite enzyme to act more effectively on components such as proteins in the black soldier fly larvae powder, improves the enzymatic hydrolysis efficiency, and thus obtains more polypeptide products. The glycoside hydrolase in the composite enzyme removes sugar impurities bound to the polypeptide, improving the purity and quality of the polypeptide.

[0088] Compared with Example 3 and Comparative Example 3, lipid impurities in black soldier fly larvae can be effectively removed by using a specific organic solvent for extraction under certain conditions. After the lipids are removed, the enzymatic hydrolysis reaction can be carried out more fully, thereby improving the yield and quality of the polypeptide.

[0089] Compared with Example 3 and Comparative Example 4, the swept-frequency pulse ultrasound can produce strong mechanical vibration and cavitation effect, making the defatted insect powder particles more dispersed, increasing the contact area between the substrate and the complex enzyme, thereby increasing the rate of the enzymatic hydrolysis reaction; the ultrasonic action can cause slight changes in the molecular structure of the enzyme, which may change the active conformation of the enzyme, making its active center more exposed, thereby improving the catalytic activity of the enzyme, reducing the introduction of microbial contamination and other impurities that may occur during the enzymatic hydrolysis process, thereby improving the purity of the black soldier fly polypeptide.

[0090] Test Example 3 - Determination of Antioxidant Activity

[0091] The black soldier fly polypeptide obtained in Example 1-3 was measured according to GB / T39100-2020:

[0092] 1. DPPH free radical scavenging experiment:

[0093] (1) Preparation of DPPH solution: Dissolve DPPH in anhydrous ethanol to a concentration of 0.1 mmol / L.

[0094] (2) Sample preparation: The black soldier fly polypeptide sample was dissolved in phosphate buffer to prepare a sample solution with a concentration of 0.5 mg / mL.

[0095] (3) Establishment of reaction system: Add 3 mL of DPPH solution and 1 mL of sample solution into a test tube and mix well.

[0096] (4) Incubation: Incubate the reaction system in the dark for 30 minutes to allow the reaction to proceed fully.

[0097] (5) Determine absorbance: Use a UV-visible spectrophotometer to measure the absorbance of the reaction system at 517 nm.

[0098] (6) Calculation of free radical scavenging rate: Calculate the scavenging rate of the sample on DPPH free radicals according to the following formula:

[0099] Clearance = [1-(A sample-A blank) / A control] × 100%. A sample is the absorbance of the sample solution after the reaction with DPPH, A blank is the absorbance of the sample solution itself at 517 nm, and A control is the absorbance of the DPPH solution after the reaction with the solvent.

[0100] 2. ABTS free radical scavenging experiment

[0101] (1) Prepare ABTS working solution: dissolve ABTS and potassium persulfate in water, mix and react in the dark for 6 hours.

[0102] (2) Sample preparation: Same as DPPH free radical scavenging method.

[0103] (3) Establishment of reaction system: Add 3 mL of DPPH solution and 1 mL of sample solution into a test tube and mix well.

[0104] (4) Incubation: Incubate at room temperature for 6 minutes.

[0105] (5) Determine absorbance: Measure the absorbance of the reaction system at 734 nm.

[0106] (6) Calculation of free radical scavenging rate: The calculation formula is the same as the DPPH free radical scavenging method.

[0107] 3. Reducing power determination method

[0108] (1) Preparing a reaction solution: Mix potassium ferrocyanide, phosphate buffer, etc. to prepare a reaction solution.

[0109] (2) Prepare samples: same as above.

[0110] (3) Establishment of reaction system: Add 3 mL of DPPH solution and 1 mL of sample solution into a test tube, mix well, and react at 50°C for 20 minutes.

[0111] (4) Adding trichloroacetic acid: After the reaction is completed, trichloroacetic acid is added to terminate the reaction and precipitate macromolecules such as proteins in the reaction system.

[0112] (5) Determine absorbance: Take the supernatant, add ferric chloride solution, mix, and then measure the absorbance at 700 nm.

[0113] Table 3:

[0114] DPPH free radical scavenging rate ABTS free radical scavenging rate Reducing ability (absorbance value) Experimental Group 1 79.9％ 80.2％ 0.91 Experimental Group 2 80.1％ 85.5％ 0.92 Experimental Group 3 85.3％ 87.1％ 0.98

[0115] The present invention helps to improve the purity of the black soldier fly polypeptide through the desugaring and defatting steps, and reduce impurities that may affect product performance. The swept-frequency pulse ultrasound-assisted enzymolysis can control the degree of enzymolysis to a certain extent, reduce the occurrence of side reactions, and adjust the ultrasound parameters to avoid excessive enzymolysis resulting in too small a molecular weight of the polypeptide or the generation of undesirable by-products, thereby improving the quality of the product. When the black soldier fly polypeptide is used as an animal feed or organic fertilizer additive, it can better improve the immunity of the animal and promote its growth.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for preparing a black soldier fly polypeptide, characterized in that: The following steps are involved: S1. Cleaning and disinfection: Select healthy, disease-free, well-grown black soldier fly larvae, rinse them with clean water for 3-5 times, soak them in 5%-10% saline for 20-30 minutes, and finally irradiate them with ultraviolet light for 15-25 minutes; S2, crushing: crushing the treated black soldier fly larvae, using ultrafine crushing technology to crush the black soldier fly larvae to a particle size of 10-50 μm, to obtain black soldier fly larvae powder; S3, desugaring: take the black soldier fly larvae powder and add physiological saline to stir and homogenize, place in a centrifuge, centrifuge at 7-10°C, 700-900×g for 10-20 min, discard the supernatant, take precipitate I and continue to add physiological saline, centrifuge at 4-6°C, 10000-13000×g for 30-50 min, aspirate the supernatant, take precipitate II, and set aside; S4, defatting: put the precipitate II into an extraction kettle, introduce an organic solvent into the extraction kettle, the mass volume ratio of the precipitate II to the organic solvent is 5-10:50 g / mL, and the organic solvent is anhydrous ethanol and n-hexane in a volume ratio of 2-5:8-10, extract it at 30-50°C and 15-30MPa for 2-4 times, each time for 1-3h, combine the extracts, separate, and obtain defatted insect powder and insect fat; S5, enzymatic hydrolysis: adding compound enzyme to the defatted insect powder, the compound enzyme addition amount is 0.5-1.5% of the mass of the insect powder, enzymatic hydrolysis for 3-4 hours at pH 6.0-7.0 and temperature 35-37°C, and applying sweep pulse ultrasound to assist enzymatic hydrolysis; S6. Separation and purification: The above enzymatic hydrolysate is subjected to ultrafiltration treatment at a flow rate of 1-5 m / s to obtain a black soldier fly polypeptide with a molecular weight of ≤1 kDa.

2. The process for preparing a black soldier fly polypeptide according to claim 1, characterized in that: The ultraviolet irradiation intensity of S1 is 1000-5000 μW / cm2.

3. The process for preparing a black soldier fly polypeptide according to claim 1, characterized in that: The mass volume ratio of the black soldier fly larvae powder and physiological saline in S3 is 0.3-0.8:20 g / mL.

4. The process for preparing a black soldier fly polypeptide according to claim 1, characterized in that: The mass volume ratio g / mL of the S3 precipitate I and the physiological saline is 0.9-1.3:

30.

5. The process for preparing a black soldier fly polypeptide according to claim 1, characterized in that: The complex enzyme of S5 is chitinase, protease and glycoside hydrolase in a mass ratio of (5.8-9.5):(2.6-3.5):(4.5-8.2), and the enzyme activity is greater than 10000 U / g.

6. The process for preparing a black soldier fly polypeptide according to claim 1, characterized in that: The ultrasonic frequency in S5 is 32-50kHz, the ultrasonic power is 50-300W, and the sweep frequency range is 20-100kHz.

7. The process for preparing a black soldier fly polypeptide according to claim 1, characterized in that: The ultrafiltration pressure in S6 is 0.1-0.5 MPa and the temperature is 20-25°C.

8. Antioxidant use of the black soldier fly polypeptide obtained by the preparation process of the black soldier fly polypeptide according to any one of claims 1 to 7.

9. The antioxidant use according to claim 8, characterized in that: Used to prepare animal feed or organic fertilizer.

10. The antioxidant use according to claim 9, characterized in that: The animals include aquatic animals or mammals.

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