Protease-containing high-cellulose silkworm larva feed and preparation method thereof

Abstract

The invention discloses a protease-containing high-cellulose silkworm larva feed and a preparation method thereof, and belongs to the technical field of enzyme engineering of biological agriculture and related industries and feeds for feeding animals, and the protease-containing high-cellulose silkworm larva feed comprises protease preparation-mulberry shoot powder composite powder, mulberry shoot powder, corn flour, soybean meal, citric acid, inorganic salt and guar gum. The characteristic that fresh mulberry branches are easy to smash is utilized, the mode of drying after smashing is adopted, the drying time of the mulberry branches is shortened, the mulberry branches are artificial feed and contain sufficient cellulose, feeding of silkworm larvae is facilitated, peristalsis of the feed in silkworm bodies is promoted, and the requirements for feeding habits, main nutrition and physiological growth of silkworms are met; the proportion of corn flour is increased, and carbohydrates and carbohydrates required by the growth of the silkworms are provided; the guar gum has good water retention performance, the cooked silkworm larva feed is not easy to dry and harden, and the protease preparation is used to effectively supplement protease in silkworm larva bodies and promote the growth and development of the silkworm larvae.

Description

Technical Field

[0001] The invention belongs to the technical field of enzyme engineering and animal feeding feed in biological agriculture and related industries, and more specifically, the invention relates to a high-cellulose silkworm larvae feed containing protease and a preparation method thereof. Background Art

[0002] During the growth of silkworm larvae, feeding with a certain amount of protease can improve the utilization rate of feed, promote the growth and development of silkworm larvae, resist the invasion of insect pathogenic fungi, and reduce the morbidity of silkworm larvae. At the same time, the current feeding of silkworm larvae is mainly based on mulberry leaves, and the cellulose content of mulberry leaves is lower than that of mulberry branches, and cellulose is conducive to improving the intestinal peristalsis of silkworm larvae and improving the feeding of silkworm larvae. Therefore, it is necessary to utilize the high cellulose content of mulberry branches and use mulberry branches as the main feed ingredient for feeding silkworm larvae. Mulberry branches are hard in texture and can only be ground into powder for silkworm larvae to eat. Alkaline protease is an enzyme that can hydrolyze protein in an alkaline environment. In the midgut tissue of silkworm larvae, there is an alkaline protease that can decompose casein and BAPNA (benzoylarginine for p-nitroaniline), which are synthesized in the midgut tissue and located at the fine line edge after synthesis, belonging to a membrane-bound enzyme. These alkaline proteases play a key auxiliary role in the silkworm larvae's ingestion and digestion of feed.

[0003] Serine proteases are a type of protease with serine as the active center, which has broad substrate specificity and hydrolytic activity. In the body of silkworms, serine protease p37k exhibits different activities in different parts, especially in the midgut, where it has strong gelatinase activity, which helps silkworm larvae to effectively digest protein in feed. In view of this, adding serine proteases to feed can further enhance the digestion efficiency of silkworm larvae for protein.

[0004] In actual operation, the amount of protease added needs to take into account many factors, such as the growth stage of the silkworm larvae, the feed ingredients used, and the environmental conditions during feeding. If too much protease is added, it may cause feed waste and may pollute the environment; but if the amount added is too little, it cannot provide sufficient support for the growth of the silkworm larvae.

[0005] During the entire growth cycle of silkworms, the demand for proteases varies at different stages. For example, the digestive organs of newly hatched larvae are still in the process of development, and their digestive ability is relatively weak, so their tolerance and demand for proteases are not high; while larvae that are about to form cocoons need higher protein digestion efficiency to meet the large accumulation of silk protein, and their demand for proteases will increase. At the same time, the composition of the feed will also affect the amount of protease added. If the feed is rich in high-content and complex protein, more proteases may be needed to ensure its effective digestion; conversely, if there are more easily digestible substances in the feed ingredients, the amount of protease added can be appropriately reduced. In addition, factors such as temperature and humidity in the breeding environment will also affect the digestive ability of silkworm larvae. Under a suitable environment, the metabolism and digestive function of silkworm larvae are in a normal state, and the utilization efficiency of proteases is high. Under extreme environmental conditions, the digestive function may be inhibited. At this time, the adjustment of the amount of protease added should be more cautious to avoid unnecessary waste of resources and environmental pollution.

[0006] At present, there are no reports or literature on the combination of mulberry powder and protease preparations as feed for silkworm larvae. How to determine the ratio and combination method of mulberry powder and protease, while improving the activity and storage time of the protein, is a problem that needs to be solved. Summary of the invention

[0007] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0008] In order to achieve these purposes and other advantages according to the present invention, a high-cellulose silkworm larvae feed containing protease is provided, which comprises, by weight: 1 to 5 parts of protease preparation-mulberry powder composite powder, 20 to 30 parts of mulberry powder, 40 to 50 parts of corn flour, 10 to 30 parts of soybean meal powder, 1 to 6 parts of citric acid, 1 to 3 parts of inorganic salts, and 0.1 to 1 part of guar gum.

[0009] Preferably, the preparation method of mulberry powder comprises: crushing hybrid mulberry branches with leaves into fragments with a length not exceeding 3 mm by a crusher, then quickly drying them by a dryer, and then crushing them into mulberry powder with a particle size not greater than 0.15 mm by a grinder.

[0010] Preferably, the preparation method of the protease preparation-mulberry powder composite powder comprises:

[0011] S1. Disperse mulberry powder in citric acid solution, stir and heat to 40-60°C, keep warm for 1-3h, and stir at 200-500rpm; after cooling to room temperature, filter out mulberry powder, wash with deionized water several times, and dry to obtain citric acid-treated mulberry powder;

[0012] S2, adding the citric acid treated mulberry powder to the chitosan solution, and dispersing it ultrasonically at 40-60 kHz for 20-30 minutes to form a chitosan dispersion of the mulberry powder;

[0013] S3. Add the protease preparation to the chitosan dispersion of mulberry powder, keep stirring at a speed of 200-500 rpm and add jingpinnib. After stirring for 10-30 minutes, let it stand for 6-12 hours, and freeze-dry at -25--20°C for 3 hours to obtain a composite powder of protease preparation-mulberry powder.

[0014] Preferably, in said S1, the concentration of the citric acid solution is 1-5wt%, and the usage ratio of the mulberry powder to the citric acid solution is 2-10g:200-500mL;

[0015] In said S2, the concentration of the chitosan solution is 1-3wt%, and the ratio of the citric acid treated mulberry powder to the chitosan solution is 2-10g:100-250mL;

[0016] In S3, the ratio of the amount of the protease preparation to the amount of the mulberry powder treated with citric acid is 0.1-2:2-10, and the amount of jingpinnilide is 0.1-0.5% of the mass of the protease preparation.

[0017] Preferably, the preparation method of the protease preparation comprises:

[0018] S21, preparing phosphate buffer saline (PBS), adding protease powder into the phosphate buffer saline (PBS); adding quercetin into anhydrous ethanol to obtain a quercetin solution;

[0019] S22, mixing equal volumes of a phosphate buffer solution (PBS) and a quercetin solution, adding cottonseed protein to the mixed solution, dispersing by ultrasonication, and standing for 12 to 24 hours to obtain a cottonseed protein-modified quercetin solution; then injecting deionized water, and adding citric acid to adjust the pH of the system to 4 to 5, so that the solubility of the cottonseed protein-modified quercetin decreases and precipitates, separating the lower layer solution, evaporating and removing ethanol, and obtaining a quercetin phase loaded with protease;

[0020] S23. Evenly mix the quercetin phase and the sodium alginate solution to obtain a mixed dispersion system, dropwise add the calcium chloride solution into the mixed dispersion system, and stir at a speed of 100-120 rpm. After the addition is completed, stop stirring, let it stand for 5-12 hours, separate the solidified gel, and freeze-dry to obtain a protease preparation.

[0021] Preferably, in said S21, the usage ratio of phosphate buffer PBS, protease powder, quercetin and anhydrous ethanol is 1-20 mL: 10-15 mg: 10-30 mg: 50-150 mL;

[0022] In S22, the mass ratio of cottonseed protein to quercetin is 1-5:10-15, the volume of deionized water is 2-5 times the volume of the quercetin solution; the ultrasonic dispersion frequency is 30-60 kHz, and the ultrasonic dispersion time is 10-20 min.

[0023] Preferably, in S23, the concentration of the sodium alginate solution is 0.2-0.6wt%, the volume ratio of the sodium alginate solution to the quercetin phase is 1-3:2-3; the concentration of the calcium chloride solution is 10-30wt%; the freeze-drying temperature is -25--18°C, and the freeze-drying time is 1-3h.

[0024] Preferably, the inorganic salt is one or more of sodium chloride, potassium dihydrogen phosphate, calcium chloride and magnesium sulfate.

[0025] A method for preparing a high-cellulose silkworm larvae feed containing protease, comprising the following steps:

[0026] Step 1: Evenly mix mulberry powder, corn powder and soybean meal powder to obtain mixed coarse material;

[0027] Step 2: dissolving citric acid, inorganic salt and guar gum in 100 to 150 parts by weight of water, then adding the mixed coarse material, stirring and mixing evenly, steaming and filtering to obtain a mixed slurry;

[0028] Step 3: Add the protease preparation-mulberry powder composite powder to the mixed slurry to obtain a high-cellulose silkworm larvae feed containing protease.

[0029] Preferably, the cooking temperature is 100-120° C. and the cooking time is 20-60 min.

[0030] The present invention at least has the following beneficial effects: the present invention utilizes the characteristic that fresh mulberry branches are easy to crush, adopts the method of drying after crushing, shortens the drying time of mulberry branches, and mulberry branches contain sufficient cellulose as artificial feed, which is conducive to the feeding of silkworm larvae, promotes the peristalsis of feed in the silkworm body, and is conducive to meeting the feeding, main nutrition and physiological growth requirements of silkworms; increases the proportion of corn flour, and provides sugars and glycosylated compounds required for the growth of silkworms; guar gum has good water retention performance, and the silkworm feed after steaming is not easy to dry and harden. The quickly dried mulberry powder retains a large amount of vitamins, food attractants and other nutrients, which is conducive to improving the growth health of silkworm larvae.

[0031] The present invention adds a protease preparation-mulberry powder composite powder to the high-cellulose silkworm larvae feed. During the growth process of the silkworm larvae, feeding the high-cellulose silkworm larvae feed of the present invention can effectively supplement the protease in the silkworm larvae, promote the growth and development of the silkworm larvae, resist the invasion of insect pathogenic fungi, and thus reduce the morbidity of the silkworm larvae. At the same time, in the preparation method of the protease preparation of the present invention, an anti-solvent method is used, quercetin modified with cottonseed protein is used to load the protease, and the covalent interaction between cottonseed protein, quercetin and the protease is utilized to achieve efficient loading of the protease, thereby increasing the loading amount of the protease, and sodium alginate gel is used to coat the protease, thereby ensuring that the activity of the protease in the protease preparation is maintained at a high level within 60 days, thereby effectively extending the storage time of the protease preparation; finally, chitosan is used as a binder, and mulberry powder is coated on the surface of the protease preparation to obtain a protease preparation-mulberry powder composite powder, and the coating of the mulberry powder provides a stable protective layer for the protease preparation, thereby not only providing effective protection for the protease in the protease preparation, but also further extending the storage time of the protease preparation, and the mulberry powder also has a controlled release effect on the protease, thereby increasing the utilization rate of the protease in the silkworm larvae, and simultaneously increasing the biocompatibility of the protease preparation.

[0032] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION

[0033] The present invention is described in further detail below so that those skilled in the art can implement it according to the description.

[0034] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0035] The preparation method of the protease preparation used in Example 1 to Example 3 and Comparative Example 1 comprises the following steps:

[0036] S21, preparing 200 mL of phosphate buffer solution (PBS) with a pH value of 7.4, adding 150 mg of serine protease (proteinase K) powder to the phosphate buffer solution; adding 200 mg of quercetin to 500 mL of anhydrous ethanol, and dissolving to obtain a quercetin solution;

[0037] S22, mixing 200 mL of phosphate buffer dispersed with serine protease powder with 200 mL of quercetin solution to obtain a mixed solution, adding 45 mg of cottonseed protein powder to the mixed solution, dispersing it at 40 kHz ultrasonically for 20 min, and letting it stand for 12 h; then injecting 500 mL of deionized water, the solubility of cottonseed protein-modified quercetin decreases and precipitates, separating the lower layer solution, evaporating and removing ethanol, and obtaining a quercetin phase loaded with serine protease;

[0038] S23. Evenly mix 100 mL of quercetin phase and 100 mL of 0.6 wt% sodium alginate solution to obtain a mixed dispersion system, dropwise add 25 mL of 30 wt% calcium chloride solution into the mixed dispersion system while stirring at 100 rpm. After the addition is completed, stop stirring, let stand for 12 h, separate the solidified gel, and freeze-dry at -25°C for 3 h to obtain a protease preparation.

[0039] Example 1

[0040] This embodiment provides a method for preparing a high-cellulose silkworm larvae feed containing protease, comprising the following steps:

[0041] Step 1: Evenly mix 400 g of mulberry powder, 450 g of corn powder, and 200 g of soybean meal powder to obtain a mixed coarse material;

[0042] Step 2: dissolve 30 g of citric acid, 15 g of potassium dihydrogen phosphate, and 5 g of guar gum in 1200 mL of water, then add the mixed crude material, stir and mix evenly, cook at 120° C. for 20 min, and filter to obtain a mixed slurry;

[0043] Step 3: Add 10 g of protease preparation-mulberry powder composite powder to the mixed slurry to obtain a high-cellulose silkworm larvae feed containing protease.

[0044] The preparation method of the protease preparation-mulberry powder composite powder comprises:

[0045] S1. Disperse 5 g of mulberry powder in 250 mL of 5 wt% citric acid solution, stir and heat to 60°C, keep warm for 2 h, and stir at 300 rpm; after cooling to room temperature, filter out the mulberry powder, wash it with deionized water several times, and dry it to obtain the citric acid-treated mulberry powder;

[0046] S2, adding 5 g of citric acid-treated mulberry powder into 100 mL of 1 wt% chitosan solution, and dispersing by ultrasonic at 60 kHz for 30 min to form a chitosan dispersion of mulberry powder;

[0047] S3. Add 2 g of protease preparation to the chitosan dispersion of mulberry powder, keep stirring at 500 rpm and add 10 mg of jingpinnilide. After stirring for 30 minutes, let it stand for 8 hours, and freeze-dry at -25°C for 3 hours to obtain a composite powder of protease preparation and mulberry powder.

[0048] Example 2

[0049] This embodiment provides a method for preparing a high-cellulose silkworm larvae feed containing protease, comprising the following steps:

[0050] Step 1: Evenly mix 400 g of mulberry powder, 450 g of corn powder, and 200 g of soybean meal powder to obtain a mixed coarse material;

[0051] Step 2: dissolve 30 g of citric acid, 15 g of potassium dihydrogen phosphate, and 5 g of guar gum in 1200 mL of water, then add the mixed crude material, stir and mix evenly, cook at 120° C. for 20 min, and filter to obtain a mixed slurry;

[0052] Step 3: Add 20 g of protease preparation-mulberry powder composite powder to the mixed slurry to obtain a high-cellulose silkworm larvae feed containing protease.

[0053] The preparation method of the protease preparation-mulberry powder composite powder comprises:

[0054] S1. Disperse 8 g of mulberry powder in 250 mL of 5 wt% citric acid solution, stir and heat to 60°C, keep warm for 2 h, and stir at 400 rpm; after cooling to room temperature, filter out the mulberry powder, wash it with deionized water several times, and dry it to obtain the citric acid-treated mulberry powder;

[0055] S2, adding 5 g of citric acid-treated mulberry powder into 100 mL of 2 wt% chitosan solution, and dispersing by ultrasonic at 60 kHz for 30 min to form a chitosan dispersion of mulberry powder;

[0056] S3. Add 1.5 g of the protease preparation to the chitosan dispersion of mulberry powder, continue stirring at 500 rpm and add 7.5 mg of jingpinnilide. After stirring for 30 minutes, let it stand for 8 hours, and freeze-dry at -25°C for 3 hours to obtain a composite powder of the protease preparation and mulberry powder.

[0057] Example 3

[0058] This embodiment provides a method for preparing a high-cellulose silkworm larvae feed containing protease, comprising the following steps:

[0059] Step 1: Evenly mix 400 g of mulberry powder, 450 g of corn powder, and 200 g of soybean meal powder to obtain a mixed coarse material;

[0060] Step 2: dissolve 30 g of citric acid, 15 g of potassium dihydrogen phosphate, and 5 g of guar gum in 1200 mL of water, then add the mixed crude material, stir and mix evenly, cook at 120° C. for 20 min, and filter to obtain a mixed slurry;

[0061] Step 3: Add 50 g of protease preparation-mulberry powder composite powder to the mixed slurry to obtain a high-cellulose silkworm larvae feed containing protease.

[0062] The preparation method of the protease preparation-mulberry powder composite powder comprises:

[0063] S1. Disperse 10 g of mulberry powder in 300 mL of 5 wt% citric acid solution, stir and heat to 60°C, keep warm for 3 h, and stir at 500 rpm; after cooling to room temperature, filter out the mulberry powder, wash it with deionized water several times, and dry it to obtain the citric acid-treated mulberry powder;

[0064] S2, adding 5 g of citric acid-treated mulberry powder into 100 mL of 3 wt% chitosan solution, and dispersing by ultrasonic at 60 kHz for 30 min to form a chitosan dispersion of mulberry powder;

[0065] S3. Add 2 g of protease preparation to the chitosan dispersion of mulberry powder, keep stirring at 500 rpm and add 8 mg of jingipinil. After stirring for 30 min, let stand for 8 h, and freeze-dry at -25°C for 3 h to obtain a composite powder of protease preparation and mulberry powder.

[0066] Comparative Example 1

[0067] This comparative example provides a method for preparing a high-cellulose silkworm larvae feed containing protease. The difference from Example 1 is that this comparative example uses an equal mass of protease preparation to replace the protease preparation-mulberry powder composite powder, and the preparation method of the protease preparation in this comparative example is the same as that of Examples 1 to 3.

[0068] The proportions and preparation methods of the remaining raw materials in this comparative example are the same as those in Example 1.

[0069] Comparative Example 2

[0070] This comparative example provides a method for preparing a high-cellulose silkworm larvae feed containing protease. The difference from Example 1 is that the preparation method of the protease preparation in the protease preparation-mulberry powder composite powder of this comparative example is replaced by:

[0071] S21, preparing 200 mL of phosphate buffer (PBS) with a pH value of 7.4, and adding 150 mg of serine protease (proteinase K) powder into the phosphate buffer;

[0072] S22. Evenly mix 200 mL of phosphate buffer containing serine protease powder and 100 mL of 0.6 wt% sodium alginate solution to obtain a mixed dispersion system. Add 25 mL of 30 wt% calcium chloride solution dropwise into the mixed dispersion system while stirring at 100 rpm. After the addition is completed, stop stirring, let stand for 12 h, separate the solidified gel, and freeze-dry at -25°C for 3 h to obtain a protease preparation.

[0073] The protease preparation-mulberry powder composite powder and preparation method used in this example and the preparation methods of the remaining steps are the same as those in Example 1.

[0074] Comparative Example 3

[0075] This comparative example provides a method for preparing a high-cellulose silkworm larvae feed containing protease. The difference from Example 1 is that the preparation method of the protease preparation in the protease preparation-mulberry powder composite powder of this comparative example is replaced by:

[0076] S21, preparing 200 mL of phosphate buffer solution (PBS) with a pH value of 7.4, adding 150 mg of serine protease (proteinase K) powder to the phosphate buffer solution; adding 200 mg of quercetin to 500 mL of anhydrous ethanol, and dissolving to obtain a quercetin solution;

[0077] S22, mixing 200 mL of phosphate buffer dispersed with serine protease powder with 200 mL of quercetin solution to obtain a mixed solution, adding 45 mg of cottonseed protein powder to the mixed solution, dispersing it at 40 kHz ultrasonically for 20 min, and letting it stand for 12 h; then injecting 500 mL of deionized water, the solubility of cottonseed protein-modified quercetin decreases and precipitates, separating the lower layer solution, evaporating and removing ethanol, and obtaining a quercetin phase loaded with serine protease;

[0078] In this comparative example, an equal mass of quercetin loaded with serine protease is used to replace the protease preparation in Example 1, and the protease preparation-mulberry powder composite powder and preparation method of this comparative example as well as the preparation methods of the remaining steps are the same as those in Example 1.

[0079] The serine protease loading of the protease preparations used in Examples 1 to 3 and the protease preparations in Comparative Examples 2 and 3 was measured respectively, and the results were shown in Table 1:

[0080]

[0081]

[0082] At the same time, 100 g of the protease preparations used in Examples 1 to 3 and Comparative Example 1, the protease preparation-mulberry powder composite prepared in Example, Example 2 and Example 3, and the protease preparations prepared in Comparative Example 2 and Comparative Example 3 were respectively weighed and sealed at 25 ° C. Samples were taken at 0 days, 10 days, 30 days, 40 days, and 60 days, and the enzyme activity of serine protease (proteinase K) was determined. The determination method was in accordance with GB / T 34800-2017, and Table 2 was obtained:

[0083] Table 2 Changes in protease activity of each sample

[0084]

[0085] 800 1-year-old silkworm larvae were selected and divided into 8 groups. The first group was fed with the high-cellulose silkworm larvae feed containing protease prepared in Example 1, the second group was fed with the high-cellulose silkworm larvae feed containing protease prepared in Example 2, the third group was fed with the high-cellulose silkworm larvae feed containing protease prepared in Example 3, the fourth group was fed with the high-cellulose silkworm larvae feed containing protease prepared in Comparative Example 1, the fifth group was fed with the high-cellulose silkworm larvae feed containing protease prepared in Comparative Example 2, the sixth group was fed with the high-cellulose silkworm larvae feed containing protease prepared in Comparative Example 3, and the seventh group was used as blank control 1, and was fed with the high-cellulose silkworm larvae feed without adding the protease preparation-mulberry powder composite powder, and without adding the protease preparation The preparation method of the high-cellulose silkworm larvae feed of the composite powder of mulberry powder without adding the protease preparation is the same as that of Example 1. The 8th group was fed with the silkworm larvae feed without adding the mulberry powder, and the preparation method thereof was as follows: 850g corn flour and 200g soybean meal powder were mixed evenly to obtain a mixed coarse material; 30g citric acid, 15g potassium dihydrogen phosphate and 5g guar gum were dissolved in 1200mL of water, and then the mixed coarse material was added, stirred and mixed evenly, and then steamed at 120°C for 20min, and filtered to obtain a mixed slurry; 10g protease preparation was added to the mixed slurry to obtain the silkworm larvae feed without adding the mulberry powder; the feeding rate of each group was measured, and the results were shown in Table 3:

[0086] Table 3 Feeding rate of silkworm larvae in each group

[0087]

[0088]

[0089] It can be seen from the above table that the artificial silkworm larvae fed with the high-cellulose silkworm larvae feed containing protease prepared in Examples 1 to 3 have a higher feeding rate.

[0090] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0091] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the examples shown and described herein.

Claims

1. A high-cellulose silkworm larvae feed containing protease, characterized in that: The composition comprises, by weight: 1-5 parts of protease preparation-mulberry powder composite powder, 20-30 parts of mulberry powder, 40-50 parts of corn flour, 10-30 parts of soybean meal powder, 1-6 parts of citric acid, 1-3 parts of inorganic salt, and 0.1-1 parts of guar gum.

2. The high-cellulose silkworm larvae feed containing protease according to claim 1, characterized in that: The preparation method of mulberry powder comprises: crushing hybrid mulberry branches with leaves into fragments with a length not exceeding 3 mm by a crusher, then quickly drying them by a dryer, and then crushing them into mulberry powder with a particle size not exceeding 0.15 mm by a grinder.

3. The high-cellulose silkworm larvae feed containing protease according to claim 2, characterized in that: The preparation method of the protease preparation-mulberry powder composite powder comprises: S1. Disperse mulberry powder in citric acid solution, stir and heat to 40-60°C, keep warm for 1-3h, and stir at a speed of 200-500rpm; after cooling to room temperature, filter out the mulberry powder, wash it with deionized water several times, and dry it to obtain citric acid-treated mulberry powder; S2, adding citric acid treated mulberry powder to the chitosan solution, and dispersing by ultrasonic at 40-60 kHz for 20-30 min to form a chitosan dispersion of mulberry powder; S3. Add the protease preparation to the chitosan dispersion of mulberry powder, keep stirring at a speed of 200-500 rpm and add jingpinnib. After stirring for 10-30 minutes, let it stand for 6-12 hours, and freeze-dry at -25--20℃ for 3 hours to obtain a composite powder of protease preparation-mulberry powder.

4. The high-cellulose silkworm larvae feed containing protease according to claim 3, characterized in that: In S1, the concentration of the citric acid solution is 1-5wt%, and the usage ratio of the mulberry powder to the citric acid solution is 2-10g:200-500mL; In S2, the concentration of the chitosan solution is 1-3 wt %, and the ratio of the citric acid treated mulberry powder to the chitosan solution is 2-10 g: 100-250 mL; In S3, the ratio of the amount of the protease preparation to the amount of the mulberry powder treated with citric acid is 0.1-2:2-10, and the amount of jingpinnilide is 0.1-0.5% of the mass of the protease preparation.

5. The high-cellulose silkworm larvae feed containing protease according to claim 1, characterized in that: The preparation method of the protease preparation comprises: S21, preparing phosphate buffer saline (PBS), adding protease powder into the phosphate buffer saline (PBS); adding quercetin into anhydrous ethanol to obtain a quercetin solution; S22, mixing equal volumes of a phosphate buffer solution (PBS) and a quercetin solution, adding cottonseed protein to the mixed solution, dispersing by ultrasonication, and standing for 12 to 24 hours to obtain a cottonseed protein-modified quercetin solution; then injecting deionized water, and adding citric acid to adjust the pH of the system to 4 to 5, so that the solubility of the cottonseed protein-modified quercetin decreases and precipitates, separating the lower layer solution, evaporating and removing ethanol, and obtaining a quercetin phase loaded with a protease; S23. Evenly mix the quercetin phase and the sodium alginate solution to obtain a mixed dispersion system, dropwise add the calcium chloride solution into the mixed dispersion system, and stir at a speed of 100-120 rpm. After the addition is completed, stop stirring, let it stand for 5-12 hours, separate the solidified gel, and freeze-dry to obtain a protease preparation.

6. The high-cellulose silkworm larvae feed containing protease according to claim 5, characterized in that: In the S21, the dosage ratio of phosphate buffer PBS, protease powder, quercetin, and anhydrous ethanol is 1-20 mL: 10-15 mg: 10-30 mg: 50-150 mL; In S22, the mass ratio of cottonseed protein to quercetin is 1-5:10-15, the volume of deionized water is 2-5 times the volume of the quercetin solution; the ultrasonic dispersion frequency is 30-60 kHz, and the ultrasonic dispersion time is 10-20 min.

7. The high-cellulose silkworm larvae feed containing protease according to claim 5, characterized in that: In the S23, the concentration of the sodium alginate solution is 0.2-0.6 wt %, and the volume ratio of the sodium alginate solution to the quercetin phase is 1-3:2-3; the concentration of the calcium chloride solution is 10-30 wt %; the freeze-drying temperature is -25--18° C., and the freeze-drying time is 1-3 h.

8. The high-cellulose silkworm larvae feed containing protease according to claim 1, characterized in that: The inorganic salt is one or more of sodium chloride, potassium dihydrogen phosphate, calcium chloride and magnesium sulfate.

9. A method for preparing a high-cellulose silkworm larvae feed containing protease according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Evenly mix mulberry powder, corn powder and soybean meal powder to obtain a mixed coarse material; Step 2: dissolving citric acid, inorganic salt and guar gum in 100-150 parts by weight of water, then adding the mixed coarse material, stirring and mixing evenly, steaming and filtering to obtain a mixed slurry; Step 3: Add the protease preparation-mulberry powder composite powder to the mixed slurry to obtain a high-cellulose silkworm larvae feed containing protease.

10. The method for preparing the high-cellulose silkworm larvae feed containing protease according to claim 9, characterized in that: The cooking temperature is 100~120℃ and the cooking time is 20~60min.

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