CN1209395C - Production method of water soluble sericin - Google Patents

Abstract

The invention relates to a method for producing water-soluble sericin proteins with different molecular weights by using silkworm cocoons as raw materials. The cleaned cocoon shells, waste silk, etc. are immersed in water or slightly alkaline solution, and after high temperature and high pressure degumming treatment, an insoluble sericin solution is obtained, and the pH value of the solution is adjusted to 8-12, and then the second High temperature and high pressure degradation treatment, by adjusting the process conditions such as temperature or pressure during degradation treatment, treatment time, pH range of degumming solution, etc., to control the molecular weight of water-soluble sericin required to achieve, so as to prepare easily water-soluble silk for different purposes Colloid solution or powder, used in biomaterials, textile finishing agents, health care products, cosmetics, polymer synthetic materials and other fields.

Description

Method for producing water-soluble sericin

Technical field

The invention relates to a method for producing various water-soluble sericin proteins with different molecular weight ranges by using silkworm cocoons (including cocoon shells, cocoon clothing, waste silk, etc.) as raw materials.

Background technique

The main components of silk are sericin and silk fibroin, which are a kind of natural polymer protein produced by silkworms. Sericin accounts for about 20-30% of the total silk protein. When silkworms spin cocoons, sericin is coated on the outside of the silk fiber to protect and glue the silk fiber. Different degrees of degumming are required in the processing and production of silk reeling and silk dyeing. In the processing of silk cotton and silk spinning or in the research and development of silk fibroin new functional materials, sericin must be completely or partially removed before subsequent processing and treatment. At present, in the above-mentioned silk production and processing process, almost all the removed sericin is not recycled, and it is completely discharged as waste liquid. Due to the high protein content in the discharged sewage, it will consume a large amount of dissolved oxygen in the water when it flows into the river, and the water will lose its self-purification. capacity, resulting in a large amount of environmental pollution and energy waste. Therefore, if sericin can be efficiently recovered and utilized in the process of silk processing and treatment to avoid environmental pollution, huge economic and social benefits will be produced.

Sericin contains more than 17% of the amino acids necessary for the human body, and 8 of the 18 amino acids that make up sericin are essential amino acids for the human body. Recent studies have shown that the non-essential amino acids serine and glycine secreted by cerebrospinal astrocytes are nutritional factors produced by glial cells (Mitoma J et al, Neurosci Res 30(2): 195-199, 1998; Mitoma J et al, J Biol Chem 273(31):19363-19366, 1998), which promotes the survival, dendritic and electrophysiological development of cultured cerebellar neurons (Furuya S et al, Porc Natl Acad SciUSA, 97(21) : 11528-11533, 2000). L-serine in sericin accounts for 33.3% of the total amount of amino acids, and glycine also contains 16.05%, and these two amino acids account for about half of the total amount. Therefore, taking more sericin or sericin hydrolyzate can improve people's memory, prevent brain aging, and prevent dementia. Studies have shown that sericin and its sericin hydrolyzate have the functions of skin care and hair care for beauty and beauty, anti-oxidation and tyrosinase activity inhibition (Japanese Patent Application No. 10-140154, 10-265403, European Patent 0841065), It can inhibit the growth of dermatitis (Japanese Patent Application No. 10-245345, 11-193210), skin cancer, and intestinal cancer (Japanese Patent Application No. 2000-256210), and can promote the absorption and digestion of mineral nutrients in the stomach (Japanese Patent Application No. 2000-256210). Zhao 2000-312568). Moreover, with the deepening of research, the new utilization value and many unknown biological functions of sericin peptide or different degradation products of sericin will be continuously discovered.

Studies have shown that sericin with larger molecular weight can be used to make biomedical materials or textile hygienic functional coating finishing of synthetic fibers and natural fibers; sericin peptides with smaller molecular weight, small molecular weight oligopeptides and some amino acid mixtures can be Used in cosmetics, medical biological drugs, functional health food, health drinks, etc.

At present, the preparation of water-soluble sericin or the method of recovering from the waste liquid containing sericin, especially the method of preparing low-molecular-weight water-soluble sericin, mostly use some inorganic salts, organic salts and other solvents for extraction. Extraction, or hydrolysis with acid and alkali, followed by dialysis, desalination or ultrafiltration purification, decolorization to make water-soluble sericin, or concentration and drying to make sericin powder. For example, the water-soluble sericin obtained after boiling, extracting, filtering, purifying, concentrating, and drying sericin with basic inorganic salts, surface-active aqueous solution, and aqueous urea solution is used as a cosmetic raw material (Japanese Patent Application No. 58-26809), Carboxylic acids such as citric acid are also used for degumming of raw silk and fabrics. From refining waste liquid, pass through inorganic coagulants such as polyaluminum chloride etc., organic polymer coagulants such as the method for precipitation collection such as polydiethylamino ethyl propionate (Japanese Patent Application No. 1-168906) or by ultrafiltration method ( JP-A-4-202435) reclaims water-soluble sericin. The ionized water generated by water electrolysis is used for degumming of silk, thereby preparing sericin peptide solution with higher purity (JP-A-10-29909).

In the method for preparing sericin mentioned above, due to the difference in solvent addition and the difference in dissolution conditions, some of the prepared sericin are large-molecular insoluble sericin, and some are water-soluble sericin peptides with a small molecular weight, so it is difficult to control the sericin. The degree of degradation and the molecular weight range of sericin. And due to the presence of high-concentration ions, it is necessary to go through processes such as dialysis, desalination or multiple ultrafiltration purification, concentration, etc. to obtain practical sericin. At present, the production of water-soluble sericin protein, especially sericin with a small molecular weight (generally below 5 kilodaltons), is mainly obtained by enzymatic or acid hydrolysis, which is difficult to control the degradation of sericin To a certain extent, it is impossible to obtain water-soluble sericin with various uses and different molecular weight ranges. Therefore, most of the above methods have complicated preparation process, high recycling cost, and low recycling efficiency, and are not suitable for the recovery of industrial sericin or the preparation of water-soluble sericin protein.

Contents of Invention

The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art, and provide a water-soluble sericin production method with simple process, clean and environment-friendly, and capable of effectively controlling the molecular weight range of sericin.

The technical solution to realize the object of the present invention is to adopt the following processing steps: 1. Degumming: clean cocoon shells, waste silk or cocoon clothing are treated in water or an aqueous solution with a pH value of 8 to 12, and are subjected to 110 to 140 ° C, 0.05 to 0.26 MPa high temperature and high pressure degumming treatment for 1 to 5 hours to prepare insoluble sericin solution; ② sericin degradation: use alkali to adjust the pH value of the above insoluble sericin solution to 8 to 12, at 110 to 140 °C, 0.05 to 0.26 Degradation treatment under MPa condition for 1-5 hours, the aqueous solution obtained after treatment is adjusted to neutrality with acid, and various water-soluble sericin solutions with different molecular weight ranges are obtained.

Dry the degumming solution described in the above technical solution to make powder, and dissolve the sericin powder with hot water before degrading the sericin.

Water-soluble sericin powder is obtained by drying the water-soluble sericin solution obtained by adopting the above-mentioned technical solution.

Compared with the prior art, the method for producing water-soluble sericin provided by the present invention has the following obvious beneficial effects:

1. Due to the use of a relatively mild sericin degumming and degradation process, only a small amount of alkali can be used to adjust the sericin solution to pH 8-12. After treatment under high temperature and high pressure, the degraded sericin solution only needs a small amount of The acid can be adjusted to neutral, and it can be used in many fields without the need for dialysis, desalination, ultrafiltration and other processes, which greatly reduces production costs and improves efficiency. After degradation treatment, about 95% of sericin is degraded to polypeptides with a molecular weight below 10kDa, and the rest are free amino acids and a small amount of taurine. This sericin fine powder is easily soluble in water, and can be completely dissolved in water above 0°C.

2. The molecular weight range of sericin can be effectively controlled by controlling the pressure or temperature of the degradation treatment, the degradation treatment time and the pH value of the sericin solution, etc., to conveniently realize the effective control of the molecular weight range of various sericin proteins.

3. There is no waste of sericin in the whole process, no harmful waste water pollution, and no large amount of chemicals used as additives. Therefore, the sericin in silk production can be recovered efficiently, and the water-soluble sericin can be produced industrially at low cost and without pollution.

4. The degummed silk fiber obtained after the first high-temperature and high-pressure degumming treatment of cocoon shells, waste silk, cocoon clothing, etc., is clean and white, and the yield and quality of the degummed silk will not be affected in any way, and can be used as silk cotton, silk spinning, etc. Various uses.

Description of drawings

Fig. 1 is the SDS-PAGE pattern of water-soluble sericin produced in different molecular weight ranges by using different process conditions in the embodiment of the present invention.

Fig. 2 is an amino acid composition map of a water-soluble sericin protein and its hydrolyzate in an embodiment of the present invention.

Detailed ways

The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Example 1:

Weigh raw materials such as cocoon shells, cocoon clothes, waste silk, etc., first rinse in warm water or in weakly alkaline aqueous solution to remove impurities and dust, then add 20 times the amount (V/W) of pure water or use NaOH to adjust the pH to 7~ 8 Immerse in an aqueous solution to make the cocoon or cocoon shell fully swell, then place it in a high-temperature and high-pressure container, and treat it at a temperature of 120°C (0.1MPa pressure) for 1 hour, take out the degummed silk after cooling, and rinse it repeatedly with water. The washing liquid and the degumming liquid are combined to obtain an insoluble sericin solution.

Adjust the above-mentioned insoluble sericin solution with NaOH, and the pH values are pH=10.0, pH=11.0 and pH=12.0 respectively; or directly spray and dry the above-mentioned degummed sericin solution to make insoluble sericin powder, and make the sericin The powder was first dissolved in hot water, and then adjusted to pH=10.0, pH=11.0 and pH=12.0 with NaOH, respectively.

The above-mentioned insoluble sericin solution with adjusted pH value was subjected to the second high temperature and high pressure degradation treatment for 1 hour, 2.5 hours and 5 hours respectively, and after cooling, the degraded sericin solution was adjusted to neutrality with HCl solution respectively, and filtered 1. After purification, various water-soluble sericin solutions with different molecular weight ranges are obtained, or the solutions are spray-dried to obtain various water-soluble sericin powders. Referring to accompanying drawing 1, the molecular weight ranges of various water-soluble sericin proteins can be clearly seen from the SDS-PAGE chart. A4, A5, and A6 correspond to the sericin solution pH values of 10.0, 11.0, and 12.0, respectively, and the molecular weight range of sericin obtained under the technological conditions of temperature 120°C and pressure 0.1Mpa degradation treatment for 1 hour; B4 , B5, and B6 respectively correspond to the pH values of sericin solution of 10.0, 11.0, and 12.0, and the molecular weight range of sericin obtained under the technological conditions of 120° C. and 0.1 MPa degradation treatment for 2.5 hours; C4, C5 and C6 respectively correspond to the sericin protein molecular weight range obtained under the process conditions of degradation treatment at a temperature of 120° C. and a pressure of 0.1 MPa for 5 hours with pH values of 10.0, 11.0 and 12.0 of the sericin solution. According to the SDS-polyacrylamide gel electrophoresis analysis of accompanying drawing 1, the method for preparing water-soluble sericin provided by the embodiment of the present invention, by changing the process conditions, such as the pH value of the sericin solution, the temperature of degradation treatment or Pressure, processing time, etc., can achieve the purpose of controlling the molecular weight range of the prepared sericin.

For the above-mentioned sericin protein obtained under various process conditions, 1 to 5 times the volume of acetone can also be added to treat it for 10 to 20 hours, and after filtering and drying, it can be made into degreased water-soluble sericin powder, which is convenient for storage. Transportation or to meet some special needs. The water-soluble sericin powder has a particle size distribution range of 0.5-20 μm, an average particle size of about 10 μm, is a white or slightly yellowish powder, and can be completely dissolved in water above 0°C. Through the hygroscopic test of this sericin powder, the results show that its hygroscopic ability is very strong.

Referring to accompanying drawing 2, amino acid analysis shows that this water-soluble sericin powder contains about 5% free amino acids, and 13.7% taurine is also contained in these free amino acids, therefore, this water-soluble sericin protein has anti- Oxidation, inhibition of tyrosine activity and many other effects.

Example 2:

Weigh 1Kg of raw materials such as cocoon shells, cocoon clothing, waste silk, etc., first rinse in warm water or in weakly alkaline aqueous solution to remove impurities and dust, and then add 20 times the amount (V/W) of pure water for immersion to make the cocoon clothing Or after the cocoon shell is fully swollen, put it in a high-temperature and high-pressure container, and treat it at a temperature of 120°C (0.1MPa pressure) for 1 hour. After cooling, take out the degummed silk, rinse it repeatedly with water, and combine the washing liquid with the degumming liquid. An insoluble sericin solution was prepared.

Use NaOH to adjust the pH of the obtained insoluble sericin solution to 11.0; or directly spray-dry the obtained insoluble sericin solution to make insoluble sericin powder, and dissolve the sericin powder with hot water first, and then Adjust to pH 11.0 with NaOH. Next, the insoluble sericin solution after adjusting the pH value above was divided into two groups D and E, the D group was at 110°C (or 0.05MPa pressure), and the E group was carried out at 125°C (or 0.135MPa pressure). Second high temperature and high pressure degradation treatment for 2.5 hours, after cooling, adjust the degraded sericin solution to neutrality with HCl solution, obtain two water-soluble sericin solutions with different molecular weights after filtration and purification, or spray dry the solution Obtain water-soluble sericin powder. According to SDS-polyacrylamide gel electrophoresis analysis, the molecular weight range of the water-soluble sericin in group D is below 90 kDa, and the molecular weight range of the water-soluble sericin in group E is below 15 kDa.

my country is a big silk-producing country, and there is a large amount of waste silk available in sericulture, silk reeling and textile production. The invention is especially suitable for the recovery of sericin in silk cotton factories and silk spinning factories and the production of water-soluble sericin (powder), and is also suitable for recovering insoluble sericin from cocoon cooking in silk reeling factories and silk refining waste liquid in dyeing and refining factories , to produce water-soluble sericin. The sericin protein can be widely used in the fields of biomedicine, biofunctional materials, health products, cosmetics, food and the like. This invention will have obvious economic benefits and important social significance.

Claims (3)

1. A method for producing water-soluble sericin, characterized in that the processing steps are as follows: ① Degumming: clean cocoon shells, waste silk or cocoon clothing are degummed in water or an aqueous solution with a pH value of 8-12, and are degummed under high temperature and high pressure at 110-140°C and 0.05-0.26MPa for 1-5 hours to obtain insoluble silk glue solution; ② Sericin degradation: Use alkali to adjust the pH value of the above-mentioned insoluble sericin solution to 8-12, degrade it at 110-140°C and 0.05-0.26MPa for 1-5 hours, adjust the obtained water-soluble sericin solution with acid To neutral, various water-soluble sericin solutions with different molecular weight ranges were obtained. 2. The method for producing water-soluble sericin according to claim 1, characterized in that: the insoluble sericin solution is dried to make powder, and before the sericin degradation treatment, the sericin is decomposed with hot water. The powder dissolves. 3. The method for producing water-soluble sericin according to claim 1 or 2, characterized in that: the obtained water-soluble sericin solution is dried to obtain water-soluble sericin powder.

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