Preparation method of silkworm protein powder
By using N-methylmorpholine oxide to dissolve silkworm protein and combining it with high-frequency shearing and extrusion filtration technology, the structural loss and pollution problems in the preparation of silkworm protein powder were solved, and efficient and environmentally friendly silkworm protein powder preparation was achieved.
Patent Information
- Application Number
- CN202510798411.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-16
- Publication Date
- 2025-09-26
AI Technical Summary
The existing methods for preparing silkworm protein powder have the problems of severe loss of silkworm protein structure, harmful residues, uneven particle size and environmental pollution.
N-methylmorpholine oxide (NMMO) was used as a solvent. The temperature and particle size of the silkworm protein solution were controlled by high-temperature vacuum dissolution, high-speed shearing, extrusion filtration and solvent replacement to prepare silkworm protein powder with uniform particle size.
The efficient preparation of silkworm protein powder with controllable particle size, high protein structure retention rate and no harmful residue is achieved, and the solvent can be recycled to reduce environmental pollution.
Smart Images
Figure CN120699085A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of biomaterials, in particular to a method for preparing silkworm protein powder. Background Art
[0002] Silkworm protein powder prepared from natural silkworm cocoons / silk contains amino acids and has good biocompatibility. It also has moisturizing, anti-oxidation and whitening effects, and is widely used in cosmetics, biomedical materials, textiles and food additives. The existing methods for preparing silkworm protein powder mainly include mechanical crushing, chemical decomposition, enzymatic hydrolysis, etc. The composite force field and friction heat (>200°C) during the mechanical crushing process will cause excessive damage to the structure and activity of silkworm protein, resulting in a decrease in effect. Chemical methods usually use strong acids or strong bases (such as concentrated sulfuric acid, sodium hydroxide) to treat silkworm cocoons / silk, which will cause damage to the protein structure. The prepared silkworm protein powder will also have residual harmful substances and will also produce waste liquid containing heavy metals to pollute the environment. The enzymatic hydrolysis method is costly and inefficient, and the prepared silkworm protein powder has uneven particle size, which affects the application effect.
[0003] Based on the above situation, how to achieve efficient preparation of silkworm protein powder with high protein activity retention, no harmful residue, green and environmental protection, and controllable particle size is the research direction that technicians in this field are committed to. Summary of the Invention
[0004] In view of the shortcomings of current silkworm protein powder preparation technology, such as high-temperature destruction of silkworm protein, excessive loss of protein activity, harmful residues in the product, uneven particle size and environmental pollution, the present invention provides a new method for preparing silkworm protein powder.
[0005] The method for preparing silkworm protein powder provided by the present invention comprises the following steps:
[0006] S1. Mechanically crushing silkworm cocoons or silk raw materials into fragments or short fibers with a size of 1 to 10 mm in at least two dimensions. The silkworm cocoons or silk raw materials are one or more of mulberry silkworm, tussah silkworm, and silkworm cocoon / silk.
[0007] S2. Dispersing the fragments or short fibers obtained in step S1 into a mixed solvent formed by N-methylmorpholine oxide (NMMO) and water to obtain a dispersion, heating the dispersion to 50-95° C. under vacuum conditions and stirring at high speed for 10-120 minutes to form a uniform silkworm protein solution.
[0008] In step S2, the silk or cocoon is first swollen in a mixed solvent and then further dissolved. During the swelling process, the mixed solvent must contain sufficient water. During the dissolution process, the water content of the mixed solvent must be reduced to increase the NMMO content, which promotes the dissolution of the silk or cocoon. This vacuuming operation has two functions: first, it accelerates water evaporation, increasing the NMMO concentration and promoting the dissolution of the silk or cocoon; second, it prevents the oxidation of silkworm protein in a high-temperature environment, thereby protecting the silkworm protein.
[0009] In this step, the weight percentage of N-methylmorpholine oxide in the mixed solvent is 50%-90%. If the concentration of N-methylmorpholine oxide is less than 50%, the silk or cocoon will not dissolve completely. If the concentration of N-methylmorpholine oxide is higher than 90%, the water content will be too low to fully swell the silk or cocoon, which will also lead to insufficient dissolution of the silk or cocoon.
[0010] S3. Transfer the silkworm protein solution obtained in step S2 to a pressure syringe while it is hot. The liquid outlet of the pressure syringe is connected to the liquid inlet of the filter through an infusion tube. The liquid outlet of the filter is connected to a porous feeler through an infusion tube. The silkworm protein solution is extruded through the pore structure and dripped into the solvent bath. The bath is stirred until the silkworm protein is precipitated in the bath, and then filtered, washed and dried to obtain a silkworm protein powder with a particle size of 0.5-10 μm. The filter mesh number of the filter is 100 to 500 meshes. A heating jacket is provided on the outside of the infusion tube to heat and keep the liquid in the tube warm to ensure that the temperature of the silkworm protein solution is maintained at 45 to 90 ° C. The solvent in the solvent bath is one or more composite solutions of ethanol, isopropanol, N-methylmorpholine oxide, and deionized water.
[0011] Preferably, in step S2, the dispersion is placed in a pressure-resistant container, evacuated to a vacuum degree of -0.085 to -0.1 MPa, and simultaneously heated to 50 to 95° C. and stirred for 10 to 120 minutes at a stirring speed of 1,000 to 20,000 r / min. The pressure-resistant container is one of a pressure-resistant thick-walled glass bottle, a corrosion-resistant stainless steel bottle, and a steel cylinder with a polytetrafluoroethylene liner.
[0012] Preferably, in step S3, the solvent in the solvent bath is a mixture of isopropyl alcohol and anhydrous ethanol in a mass ratio of 1:1. The stirring speed of the solvent bath is 500 to 15000 r / min.
[0013] Preferably, in step S3, the bottom liquid outlet of the porous die head is provided with a circular porous plate with evenly distributed circular holes, the diameter of the circular holes is 0.1 to 0.5 mm, and the number of holes is 10 to 100.
[0014] Preferably, in step S3, the silkworm protein precipitated in the solvent bath is filtered and then washed, and the washing agent is one or more of deionized water, anhydrous ethanol, acetone and isopropyl alcohol. The drying temperature is further 40-70°C.
[0015] Compared with the prior art, the present invention is beneficial in that:
[0016] (1) The present invention uses NMMO as a green solvent, and obtains silk powder material through NMMO dissolution, high-frequency shearing, extrusion filtration, solvent replacement precipitation and solid-liquid separation and drying. The protein structure of the cocoon / silk is placed in a solvent and a stable temperature field for dissolution, and at the same time, the length of the silkworm protein molecular chain is interrupted by wet high-frequency shearing, the length of the amino acid chain is reduced, a small molecule protein is formed, and a silkworm protein powder with a lower degree of polymerization is obtained. Based on the high-frequency shear rate control, the particle size of the final product silkworm protein powder can be accurately controlled. The average particle size of the prepared silkworm protein powder is 0.5-10μm, and the specific surface area is 15-30m 2 / g, β-folded structure content>90%.
[0017] (2) Compared with chemical methods, the NMMO dissolving system used in the present invention can be recycled and reused after use, with a recovery rate of over 90%, and no pollution emissions. Compared with traditional physical methods, the present invention overcomes the damage to silkworm protein caused by high temperature friction and composite force field during physical pulverization, reduces the loss of non-destructive structures, and can achieve a protein structure retention rate of up to 95%. It also solves the problem of insufficient fineness of silkworm protein powder prepared by physical methods.
[0018] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a process flow chart for preparing silk protein powder.
[0020] Figure 2 Schematic diagram of a device for preparing silkworm protein powder from silkworm protein solution.
[0021] Numbers in the figure: 1-pressure syringe, 2-filter, 3-infusion tube, 4-porous die, 5-silkworm protein solution, 6-solvent bath, 7-silkworm protein powder, 8-porous plate at the bottom liquid outlet of the porous die.
[0022] Figure 3 This is the particle size distribution curve of silkworm protein powder under different shear rates. DETAILED DESCRIPTION
[0023] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.
[0024] Example 1
[0025] A method for preparing silkworm protein powder, such as Figure 1 As shown, the steps are as follows:
[0026] 50g of decontaminated silkworm cocoons were chopped into 5mm pieces using scissors. A mixed solvent of N-methylmorpholine oxide (NMMO) and water (85:15 by mass) was prepared. The cocoon fragments were dispersed in 416g of the mixed solvent. The dispersion was transferred to a corrosion-resistant stainless steel bottle, heated to 80°C using bottom heating, and then stirred at 15,000 rpm using a high-frequency shearing stirrer. A water-circulating vacuum pump was used to evacuate the bottle to a vacuum of -0.085 MPa via a through-hole connected to the sealed, pressure-resistant, and corrosion-resistant stainless steel bottle. After 30 minutes of this treatment, a completely dissolved silkworm protein solution was obtained.
[0027] like Figure 2 As shown, the silkworm protein solution is transferred to the pressure syringe 1 while hot. The liquid outlet of the pressure syringe 1 is connected to the liquid inlet of the filter 2 through the infusion tube 3. The liquid outlet of the filter 2 is connected to the porous feeler 4 through the infusion tube 3. The silkworm protein solution 5 is extruded through the pore structure and dripped into the solvent bath 6. The bath is stirred at a speed of 1000r / min so that the dissolved silkworm protein is replaced and precipitated in the solvent bath to obtain a silkworm protein powder 7 suspension; then, it is vacuum filtered, rinsed with deionized water 3 times, and dried in a vacuum oven at 60°C for 6h to obtain silkworm protein powder. A heating jacket is set on the outside of the infusion tube to heat and keep the liquid in the tube warm, ensuring that the temperature of the silkworm protein solution is maintained at 80°C. The extrusion pressure is 1.5Mpa, which is generated by compressing the solution through the pressure syringe and the solution pipeline. The filter mesh number is 300 mesh, the porous plate 8 of the porous die head has a diameter of 45 cm, a pore size of 0.3 mm, and a pore number of 50. The solvent in the solvent bath is a mixed solvent of NMMO and deionized water in a mass ratio of 15:85.
[0028] Example 2
[0029] A method for preparing silkworm protein powder, comprising the following steps:
[0030] 50g of decontaminated silkworm cocoons were chopped into 5mm pieces using scissors. A mixed solvent of N-methylmorpholine oxide (NMMO) and water at a mass ratio of 88:12 was prepared. The cocoon fragments were dispersed in 500g of the mixed solvent, and the dispersion was transferred to a corrosion-resistant stainless steel bottle. The dispersion was heated to 85°C using bottom heating and then sheared at 18,000 rpm using a high-speed stirrer. A water-circulating vacuum pump was used to evacuate the bottle to a vacuum of -0.085 MPa through a through-hole connected to the sealed, pressure-resistant, and corrosion-resistant stainless steel bottle. After 60 minutes of this treatment, a completely dissolved silkworm protein solution was obtained.
[0031] The silkworm protein solution is transferred to a pressure syringe while hot. The liquid outlet of the pressure syringe is connected to the liquid inlet of the filter through an infusion tube. The liquid outlet of the filter is connected to a porous die through an infusion tube. The silkworm protein solution is extruded through the pore structure of the porous plate and dripped into the solvent bath. The bath is stirred at a speed of 1500r / min so that the dissolved silkworm protein is replaced and precipitated in the solvent bath to obtain a silkworm protein powder suspension; then vacuum filtered, rinsed with deionized water 3 times, and dried in a vacuum oven at 45°C for 6h to obtain silkworm protein powder. A heating jacket is provided on the outside of the infusion tube to heat and keep the liquid in the tube warm, ensuring that the temperature of the silkworm protein solution is maintained at 85°C. The extrusion pressure is 2.8Mpa, the filter mesh size is 400 mesh, the porous plate of the porous die head has a diameter of 45cm, a pore size of 0.2mm, and a pore size of 50. The solvent in the solvent bath is anhydrous ethanol.
[0032] Example 3
[0033] A method for preparing silkworm protein powder, comprising the following steps:
[0034] 50g of tussah silkworm cocoons, after impurities had been removed, were chopped into 3mm pieces using scissors. A mixed solvent of N-methylmorpholine oxide (NMMO) and water at a mass ratio of 90:10 was prepared. The cocoon fragments were dispersed in 330g of the mixed solvent, and the dispersion was transferred to a corrosion-resistant stainless steel bottle. The dispersion was heated to 80°C using bottom heating and then sheared at 20,000 rpm using a high-speed stirrer. A water-circulating vacuum pump was used to evacuate the bottle to a vacuum of -0.09 MPa through a through-hole connected to the sealed, pressure-resistant, and corrosion-resistant stainless steel bottle. After 45 minutes of this treatment, a completely dissolved silkworm protein solution was obtained.
[0035] The silkworm protein solution, while hot, was transferred to a pressure syringe. The outlet of the pressure syringe was connected to the inlet of a filter via an infusion tube. The filter outlet was then connected to a porous die head via an infusion tube. The silkworm protein solution was extruded through the pores of the porous plate and dripped into a solvent bath. The bath was stirred at 2000 rpm to displace and precipitate the dissolved silkworm protein in the solvent bath, resulting in a silkworm protein powder suspension. The suspension was then vacuum filtered, rinsed three times with deionized water, and dried in a vacuum oven at 45°C for 6 hours to obtain the silkworm protein powder. A heating jacket was installed outside the infusion tube to heat and insulate the liquid within, ensuring that the temperature of the silkworm protein solution remained at 80°C. The extrusion pressure was 3.0 MPa, the filter mesh size was 300 mesh, the circular porous plate of the porous die head had a diameter of 45 cm, a pore size of 0.2 mm, and a number of 50 holes. The solvent in the solvent bath was a 50:50 mixture of isopropyl alcohol and anhydrous ethanol by weight.
[0036] Example 4
[0037] A method for preparing silkworm protein powder, such as Figure 1 and 2 As shown, the steps are as follows:
[0038] 50g of impurity-free mulberry silk was chopped into 3mm staple fibers using scissors. A mixed solvent of N-methylmorpholine oxide (NMMO) and water at a mass ratio of 86:14 was prepared. The staple fibers were dispersed in 500g of the mixed solvent, and the dispersion was transferred to a corrosion-resistant stainless steel bottle. The dispersion was heated to 90°C using bottom heating and then sheared at 25,000 rpm using a high-speed stirrer. A water-circulating vacuum pump was used to evacuate the bottle to a vacuum of -0.085 MPa through a through-hole connected to the sealed, pressure-resistant, and corrosion-resistant stainless steel bottle. After 30 minutes of this treatment, a completely dissolved silkworm protein solution was obtained.
[0039] The silkworm protein solution is transferred to a pressure syringe while hot. The liquid outlet of the pressure syringe is connected to the liquid inlet of the filter through an infusion tube. The liquid outlet of the filter is connected to a porous die through an infusion tube. The silkworm protein solution is extruded through the pore structure of the porous plate and dripped into the solvent bath. The bath is stirred at a speed of 1000r / min so that the dissolved silkworm protein is replaced and precipitated in the solvent bath to obtain a silkworm protein powder suspension; then vacuum filtered, rinsed with deionized water 3 times, and dried in a vacuum oven at 60°C for 6h to obtain silkworm protein powder. Wherein, a heating jacket is set outside the infusion tube to heat and keep the liquid in the tube warm to ensure that the temperature of the silkworm protein solution is maintained at 90°C. The extrusion pressure is 2.5Mpa, the filter mesh size is 300 mesh, the circular porous plate of the porous die head has a diameter of 50cm, a pore size of 0.3mm, and a pore size of 60. The solvent in the solvent bath is a mixed solvent of methanol and anhydrous ethanol with a mass ratio of 50:50.
[0040] Comparative Example 1
[0041] 50 g of mulberry silkworm cocoons after impurities were removed were cut into 3 mm pieces with scissors, and then physically crushed using a grinder and a planetary ball mill to prepare silkworm protein powder.
[0042] Comparative Example 2
[0043] 50 g of mulberry silk after impurities were removed was cut into short fibers of 3 mm in length with scissors. 100 mL of formic acid and 5 g of CaCl2 were weighed to prepare a mixed solvent. The short fibers were dispersed in the mixed solvent and heated to 80 °C to dissolve. The completely dissolved solution was freeze-dried to prepare silkworm protein powder.
[0044] The performance test results of the silkworm protein powders prepared in Examples 1-4 and Comparative Examples 1 and 2 are shown in Table 1.
[0045] Table 1. Performance data of silkworm protein powder prepared in Examples 1-4 and Comparative Examples 1 and 2
[0046] project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Yield (%) 99.8 99.5 98.6 99.7 86.3 78.5 Average particle size (μm) 2.3 1.9 1.4 0.9 50.0 7.0 β-sheet structure ratio (%) 93 92 89 95 73 49 Solvent recovery rate (%) 98 99 97 98 — Cannot be recycled
[0047] As can be seen from the table, compared with the traditional preparation process, the silkworm protein powder prepared by the present invention has a smaller particle size, the protein structure in the silkworm protein is more completely preserved, and the solvent used can achieve a high proportion of recovery, and the production process is green and efficient.
[0048] On the basis of Example 1, the stirring shear speed during the dissolution of the cocoon fragments was changed to 5000, 10000, 20000, and 25000 r / min respectively, and other operations remained unchanged to prepare different silkworm protein powders. The particle size of the silkworm protein powder under different shear speeds was tested, and the test results are shown in FIG. Figure 3 As can be seen from the figure, as the shear rate increases, the particle size of the prepared silkworm protein powder decreases. This proves that the method of the present invention can accurately control the particle size of the final product silkworm protein powder based on high-frequency shear rate control.
[0049] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.
Claims
1. A method for preparing silkworm protein powder, characterized in that: The following steps are involved: S1. Crushing silk cocoons or silk raw materials into fragments or short fibers; S2. Dispersing the fragments or short fibers obtained in step S1 into a mixed solvent of N-methylmorpholine oxide and water to obtain a dispersion, heating the dispersion to 50-95° C. under vacuum conditions and stirring for 10-120 minutes to form a silkworm protein solution; wherein the mass proportion of N-methylmorpholine oxide in the mixed solvent is 50%-90%; S3. Transfer the silkworm protein solution obtained in step S2 to a pressure syringe while it is hot. The liquid outlet of the pressure syringe is connected to the liquid inlet of the filter through an infusion tube. The liquid outlet of the filter is connected to a porous feeler through an infusion tube. The silkworm protein solution is extruded through the pore structure and dripped into a solvent bath. The bath is stirred until the silkworm protein is precipitated in the bath. Then, the solution is filtered, washed, and dried to obtain a silkworm protein powder with a particle size of 0.5-10 μm. The infusion tube has heating and heat preservation functions to ensure that the temperature of the silkworm protein solution is maintained at 45-90°C.
2. The method for preparing silkworm protein powder according to claim 1, wherein In step S2, the dispersion is placed in a pressure-resistant container, and the pressure container is evacuated to a vacuum degree of -0.085 to -0.1 MPa. At the same time, the dispersion is heated to 50 to 95° C. and stirred for 10 to 120 minutes at a stirring speed of 1000 to 20,000 r / min.
3. The method for preparing silkworm protein powder according to claim 1, wherein: The solvent in the solvent bath is one or more composite solutions of ethanol, isopropanol, N-methylmorpholine oxide, and deionized water.
4. The method for preparing silkworm protein powder according to claim 3, wherein: The solvent in the solvent bath is a mixture of isopropyl alcohol and anhydrous ethanol in a mass ratio of 1:
1.
5. The method for preparing silkworm protein powder according to claim 1, wherein: In step S3, the filter mesh size is 100 to 500 meshes.
6. The method for preparing silkworm protein powder according to claim 1, wherein: In step S3, a circular porous plate with evenly distributed circular holes is provided at the bottom liquid outlet of the porous die head, wherein the diameter of the circular holes is 0.1 to 0.5 mm and the number of holes is 10 to 100.
7. The method for preparing silkworm protein powder according to claim 1, wherein: In step S3, the drying temperature is 45-60°C.
8. The method for preparing silkworm protein powder according to claim 1, wherein: In step S1, the cocoons or silk raw materials are mechanically crushed into fragments or short fibers with a size of 1 to 10 mm in at least two dimensions.