WO2024040769A1

WO2024040769A1 - Sericin protein peptide having moisturizing function, method for preparing same, and use thereof

Info

Publication number: WO2024040769A1
Application number: PCT/CN2022/133579
Authority: WO
Inventors: 蔡木易; 谷瑞增; 秦修远; 陈亮; 董哲; 张新雪; 王憬; 张海欣; 毕园; 马永庆; 方磊; 李国明; 刘文颖; 陆路
Original assignee: 中国食品发酵工业研究院有限公司
Priority date: 2022-08-25
Filing date: 2022-11-22
Publication date: 2024-02-29
Also published as: CN115093472B; CN115093472A

Abstract

The present application provides a sericin protein peptide having a moisturizing function, a method for preparing same, and use thereof. According to a first aspect of the present application, a sericin protein peptide having a moisturizing function is provided. The sericin protein peptide at least comprises peptide fragments GGS, AS, and GS. Based on the mass of the sericin protein peptide, the content of the peptide fragment GGS is ≥ 0.80%, the content of the peptide fragment AS is ≥ 0.20%, and the content of the peptide fragment GS is ≥ 0.50%. The sericin protein peptide provided in the present application contains three functional peptide segments GGS, AS, and GS, and has significant moisturizing effects.

Description

A kind of sericin peptide with moisturizing function and its preparation method and application

This application requires the priority of the Chinese patent application submitted to the China Patent Office on August 25, 2022, with the application number 202211022217.3 and the application title "A sericin peptide with moisturizing function and its preparation method and application", which The entire contents are incorporated herein by reference.

Technical field

The present application relates to a sericin peptide with moisturizing function and its preparation method and application, and relates to the technical field of silk protein processing.

Background technique

For a long time, silk has been mainly used as a textile raw material. The protein content in silk is as high as more than 98%. Since the late 1970s, researchers have gradually begun to pay attention to the new uses of silk. Currently, silk is used in daily chemicals, medicine and biology. Materials, health functional foods and other fields have been applied to varying degrees, and the development of silk protein has become a research hotspot in recent years.

Silk protein mainly includes silk fibroin and sericin. Among them, the mass of silk fibroin accounts for 70%-80% of the total mass of silk protein. It is insoluble in water and ethanol and has a compact and ordered aggregate structure. It must be treated with strong Polar solvents must destroy the structure to dissolve; the mass of sericin accounts for 20-30% of the total mass of silk protein. It is a globular protein with a relative molecular mass of 14,000-314,000 and is composed of 18 kinds of amino acids, of which serine has the highest content. Accounting for about 30%, it is easily soluble in water and has good hygroscopicity; with the in-depth research on sericin, sericin has excellent cell affinity and biocompatibility, and has tyrosinase inhibition Active, anti-UV activity, moisturizing, beauty and hair care functions.

Serine is a naturally occurring moisturizing factor in human skin. It has a good function of absorbing water molecules and is often used as a basic moisturizer in cosmetics. Sericin or silk protein rich in serine not only has the structural advantage of natural moisturizing, but also It has natural protein nutrition and skin care functional properties, and has potential in developing moisturizing functional cosmetic raw materials.

The current deep processing methods for silk protein focus on removing sericin under high temperature and high pressure, and using acid or alkali hydrolysis to obtain silk fibroin peptides, or using acid-base combined enzymatic hydrolysis to treat silk protein to prepare silk peptides. The silk fibroin peptides obtained by this method Or the free amino acid content in silk peptide is relatively high, specifically as high as 13% or more, and harmful substances may be produced or certain pollution may be caused during the treatment with acid-base reagents.

Contents of the invention

The present application provides a sericin peptide with moisturizing function. The sericin peptide contains functional peptide segments with specific mass content, such as glycine-glycine-serine (Gly-Gly-Ser, GGS) and alanine-serine. (Ala-Ser, AS) and glycine-serine (Gly-Ser, GS), thus showing good efficacy in moisturizing.

The present application also provides a method for preparing a sericin peptide with moisturizing function. The sericin peptide prepared by this preparation method contains a specific mass content of functional peptide segments, glycine-glycine-serine (Gly-Gly- Ser, GGS), alanine-serine (Ala-Ser, AS) and glycine-serine (Gly-Ser, GS), thus showing good efficacy in moisturizing.

This application also provides the application of the above-mentioned sericin peptide in moisturizing products.

The first aspect of the present application provides a sericin peptide with moisturizing function, the composition of the sericin peptide at least includes peptide segments GGS, AS and GS;

Based on the mass of the sericin peptide, the content of the peptide GGS is ≥0.80%, the content of the peptide AS is ≥0.20%, and the content of the peptide GS is ≥0.50%.

In addition, in the sericin peptide provided by this application, in addition to the above-mentioned special peptide segments, the protein content in the sericin peptide is ≥85%, the content of free amino acids is ≤5%, and the content of acid-soluble protein is ≥80%. , the content of components with a molecular weight below 1000 is ≥85%.

In a specific embodiment, the sericin peptide is obtained by using pupa-free silkworm cocoons as raw materials and sequentially undergoing sericin dissolution, fermentation, enzymatic hydrolysis, adsorption decolorization, and drying;

Wherein, the fermentation uses Candida prion;

The enzymatic hydrolysis includes using alkaline protease and neutral protease for enzymatic hydrolysis.

A second aspect of the present application provides a method for preparing any of the sericin peptides described above, including the following steps:

1) Dissolve the sericin in the pupa-free silkworm cocoons to obtain a sericin solution;

2) Use Candida utilis to ferment the sericin solution. After the fermentation is completed, a sericin fermentation liquid is obtained;

3) Add alkaline protease and neutral protease to the sericin fermentation broth for enzymatic hydrolysis. After the enzymatic hydrolysis is completed, a sericin hydrolyzate is obtained;

4) Add activated carbon to the sericin hydrolyzate for adsorption and decolorization. After the treatment, collect the filtrate and dry the filtrate to obtain the sericin peptide.

In a specific embodiment, Figure 1 is a schematic flow chart of a sericin peptide preparation method provided in an embodiment of the present application. As shown in Figure 1, the method specifically includes the following steps:

Step 1) Dissolve the sericin in the pupa-free silkworm cocoons to obtain a sericin solution;

Using commercially available pupa-free silkworm cocoons as raw materials, mix the pupa-free silkworm cocoons with pure water at a mass ratio of 1:10-30, and process it at 110-125°C for 10-90 minutes. During the treatment process, the sericin in the cocoons is dissolved. to pure water to obtain a sericin solution.

Step 2) Use Candida utilis to ferment the sericin solution. After the fermentation is completed, a sericin fermentation liquid is obtained;

Sterilize the sericin solution obtained in step 1). Sterilization can be carried out according to conventional technical means in the art, for example, sterilization at 115-121°C for 15-30 minutes. Before sterilization, the sericin solution can be concentrated. , specifically, a rotary evaporator can be used to remove part of the moisture.

After sterilization, Candida priogenum is added to the sericin solution for fermentation. The growth and metabolism of Candida priogenum can produce abundant short peptides and enzymes, which is conducive to enriching the enzyme system for the next enzymatic hydrolysis process. , it also provides exogenous peptides that are not produced by the silkworm cocoon itself, and Candida utilis does not produce ethanol under strict aerobic conditions and has good safety. Specifically, Candida utilis ) can be purchased from the China Industrial Microbiology Culture Collection Center (CICC). The strain collection number is CICC31170. Based on the mass of the pupa-free silkworm cocoon per gram, the number of colonies of the Candida primogen-producing yeast is 10 ⁵ -10 ⁷ , control the fermentation temperature to 28-32°C, culture on a shaking table, and ferment for 36-72 hours. After the fermentation is completed, filter the bacteria and collect the fermentation liquid to obtain sericin fermentation liquid.

Step 3) Add alkaline protease and neutral protease to the sericin fermentation broth for enzymatic hydrolysis. After the enzymatic hydrolysis is completed, a sericin hydrolyzate is obtained;

Alkaline protease and neutral protease are added to the sericin fermentation broth for enzymatic hydrolysis, so that the peptide bonds in the sericin are cut off to obtain short peptides. During the enzymatic hydrolysis process, based on each gram of the pupa-free silkworm cocoon, the The enzyme activity of alkaline protease is 3000-6000U, and the enzyme activity of neutral protease is 500-1500U. The temperature of enzymatic hydrolysis is controlled to be 45-55°C and the time is 4-6h. After the enzymatic hydrolysis is completed, sericin hydrolysis is obtained. liquid.

Step 4) Add activated carbon to the sericin hydrolyzate for adsorption and decolorization, collect the filtrate after the treatment, and dry the filtrate to obtain the sericin peptide;

After the enzymatic hydrolysis is completed, increase the temperature of the sericin hydrolyzate to 85-95°C, and incubate it for 15-25 minutes to inactivate the enzyme. After the enzyme is inactivated, filter to remove insoluble matter such as macromolecular proteins. Specifically, a pore size of 10KD- 20KD ceramic membrane, collect the supernatant, and add activated carbon to the supernatant for adsorption and decolorization to adsorb the pigment in the supernatant. After the adsorption treatment, remove the activated carbon, collect the filtrate and dry it to obtain sericin peptide. Drying can be carried out in the spray drying tower, and the inlet air temperature is controlled to 120-140°C and the outlet air temperature is 80-100°C.

The third aspect of the present application provides the use of any of the sericin peptides described above in moisturizing products.

The sericin peptide provided by this application clearly contains the functional peptide segments of GGS, AS and GS, and the content of the peptide GGS is ≥0.80%, the content of the peptide AS is ≥0.20%, and the content of the peptide GS is ≥0.50%. Experiments have proved that it has obvious moisturizing effect.

The implementation of this application has at least the following advantages:

1. The sericin peptide provided by this application clearly contains the functional peptide segments of GGS, AS and GS, and the content of the peptide GGS is ≥0.80%, the content of the peptide AS is ≥0.20%, and the content of the peptide GS is ≥0.50%. , has obvious moisturizing effect.

2. During the preparation process of the sericin peptide provided by this application, there is no need to use acid or alkali for treatment, and it is green and environmentally friendly.

Description of drawings

In order to more clearly explain the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description These are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting any creative effort.

Figure 1 is a schematic flow chart of a preparation method of sericin peptide provided by an embodiment of the present application;

Figure 2 is the test results of the moisturizing rate of the sericin peptide provided in the Examples of the present application and Comparative Examples 1-4;

Figure 3a shows the chromatographic detection results of GGS standard;

Figure 3b is the standard curve of GGS;

Figure 4a shows the chromatographic detection results of AS standard;

Figure 4b is the standard curve of AS;

Figure 5a shows the chromatographic detection results of GS standard;

Figure 5b is the standard curve of GS;

Figure 6a is the chromatographic detection result of GGS in the sericin peptide provided by the embodiment of the present application;

Figure 6b is the chromatographic detection result of AS in the sericin peptide provided by the embodiment of the present application;

Figure 6c is the chromatographic detection result of GS in the sericin peptide provided by the embodiment of the present application;

Figure 7a is the chromatographic detection result of GGS in the sericin peptide provided in Comparative Example 1 of the present application;

Figure 7b is the chromatographic detection result of AS in the sericin peptide provided in Comparative Example 1 of the present application;

Figure 7c is the chromatographic detection result of GS in the sericin peptide provided in Comparative Example 1 of the present application;

Figure 8a is the chromatographic detection result of GGS in the sericin peptide provided in Comparative Example 2 of the present application;

Figure 8b is the chromatographic detection result of AS in the sericin peptide provided in Comparative Example 2 of the present application;

Figure 8c is the chromatographic detection result of GS in the sericin peptide provided in Comparative Example 2 of the present application;

Figure 9a is the chromatographic detection result of GGS in the sericin peptide provided in Comparative Example 3 of the present application;

Figure 9b is the chromatographic detection result of AS in the sericin peptide provided in Comparative Example 3 of the present application;

Figure 9c is the chromatographic detection result of GS in the sericin peptide provided in Comparative Example 3 of the present application;

Figure 10a is the chromatographic detection result of GGS in the sericin peptide provided in Comparative Example 4 of the present application;

Figure 10b is the chromatographic detection result of AS in the sericin peptide provided in Comparative Example 4 of the present application;

Figure 10c is the chromatographic detection result of GS in the sericin peptide provided in Comparative Example 4 of the present application;

Figure 11 shows the test results of the moisture retention rate of the sericin peptides and characteristic peptide segments provided in the embodiments of the present application.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are part of the implementation of the present application. examples, not all examples. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

The pupae-free silkworm cocoons used in the following examples and comparative examples were purchased; Candida utilis was purchased from the China Industrial Microbial Culture Collection Center (CICC), and the strain collection number is CICC31170; alkaline protease was purchased from sigma -Aldrich Company, neutral protease was purchased from Guangxi Nanning Pangbo Bioengineering Co., Ltd., activated carbon was purchased from Guangdong Huayi Activated Carbon Co., Ltd., and sodium hydroxide was purchased from Xilong Chemical Industry.

Example

The preparation method of sericin peptide provided in this example includes the following steps:

Step 1. Weigh 100g of pupa-free silkworm cocoons, crush them in a crusher and clean them with pure water to remove dust and impurities on the surface. After removing the cleaning water, mix them with pure water at a mass ratio of 1:20, and store them at 121°C. Pressure treatment for 30 minutes. After the treatment is completed, remove insoluble matter and collect the supernatant.

Use a rotary evaporator to concentrate the supernatant, control the temperature to 80°C, and the vacuum to -0.1MPa. After half of the water in the solution has evaporated, take out the remaining solution and sterilize the remaining solution at 121°C for 15 minutes to obtain Sericin solution;

Step 2. Control the temperature of the sericin solution at 28-32°C, add activated Candida primogen with a bacterial count of 10 ⁸ (equivalent to 10 ⁶ /g pupa-free silkworm cocoons), and continue fermentation for 48 hours with a shaker at 200 rpm. , after the fermentation is completed, the sericin fermentation liquid is obtained;

Step 3. Use NaOH solution to adjust the pH of the sericin fermentation broth to 9.0, and then add alkaline protease and neutral protease at the same time. Based on each gram of pupa-free silkworm cocoons, the enzyme activity of the added alkaline protease is 5000U. The enzyme activity of the added neutral protease is 1000U, and the enzyme is hydrolyzed at 50°C for 6 hours. After the enzymatic hydrolysis is completed, a sericin hydrolyzate is obtained;

Step 4. Raise the temperature of the sericin hydrolyzate to 95°C and incubate it for 15 minutes to inactivate the protease. Use a ceramic membrane with a pore size of 10KD to filter the sericin hydrolyzate. Collect the supernatant and concentrate it. Specifically, you can use Rotary evaporator, the temperature is set to 80°C, the vacuum degree is set to -0.1MPa, and 920 mL of water in the filtrate is rotary evaporated.

Take out the remaining material liquid and heat it to 70°C, add 4g of activated carbon, stir at 70°C for 1 hour, and perform adsorption and decolorization treatment. After the treatment, remove the activated carbon and collect the supernatant;

The supernatant was sent to a spray drying tower (BH-100 pressure spray drying tower, Jiangsu Bohong) for spray drying. The inlet air temperature was controlled to 140°C and the air outlet temperature was 90°C to obtain sericin peptide.

Comparative example 1

The method provided in this comparative example can be referred to the examples. The difference is that in step 3, the enzymatic hydrolysis time is 4 hours. Specifically, NaOH solution is used to adjust the pH of the sericin fermentation broth to 9.0, and alkaline protease and neutral protein are added at the same time. Protease, perform enzymatic hydrolysis at 50°C for 4 hours, and obtain sericin hydrolyzate after the end of enzymatic hydrolysis.

Comparative example 2

The method provided in this comparative example can be referred to the examples. The difference is that in step 3, only alkaline protease is used for enzymatic hydrolysis. Specifically, NaOH solution is used to adjust the pH of the sericin fermentation broth to 9.0, and alkaline protease is added. Enzymatic hydrolysis was carried out at 50°C for 6 hours. After the enzymatic hydrolysis was completed, the sericin hydrolyzate was obtained.

Comparative example 3

The method provided in this comparative example can be referred to the examples. The difference is that in step 3, only alkaline protease is used for enzymatic hydrolysis. Specifically, NaOH solution is used to adjust the pH of the sericin fermentation broth to 9.0, and alkaline protease is added. Enzymatic hydrolysis was carried out at 50°C for 4 hours. After the enzymatic hydrolysis was completed, the sericin hydrolyzate was obtained.

Comparative example 4

The method provided in this comparative example can be referred to the examples. The difference is that in step 3, only neutral protease is used for enzymatic hydrolysis. Specifically, NaOH solution is used to adjust the pH of the sericin fermentation broth to 9.0, and neutral protease is added. Enzymatic hydrolysis was carried out at 50°C for 4 hours. After the enzymatic hydrolysis was completed, the sericin hydrolyzate was obtained.

(1) Detect the physical and chemical indicators of the sericin peptides provided in Examples and Comparative Examples 1-4. The detection method is as follows, and the detection results are shown in Table 1:

1. Moisture and ash content detection: The national standard method GB5009.3-2010 is used to determine the moisture content; the national standard method GB5009.4-2016 is used to determine the ash content.

2. Protein, peptide content, and free amino acid detection: Use the national standard method GB5009.5-2010 to determine the protein (dry basis) content; refer to the national standard method GB22729-2008 to determine the acid-soluble protein content, free amino acid content, and peptide content.

3. Distribution detection of different molecular weight components: ethyl-ethyl-ethyl-ethyl (molecular weight 189), ethyl-ethyl-tyrosine-arginine (molecular weight 451), bacillus enzyme (molecular weight 451) 1450), aprotinin (molecular weight 6500), and cytochrome C (molecular weight 12500) were prepared into 0.1% (M/V) solutions, filtered with a polytetrafluoroethylene filter membrane with a pore size of 0.2 μm, and then injected. Use the high performance liquid chromatograph (LC-20AD high performance liquid chromatograph, Shimadzu Corporation, Japan) for analysis. The mobile phase is: V (acetonitrile): V (water): V (trifluoroacetic acid) = 45:55:0.1 ; Injection volume: 10 μL; flow rate: 0.5mL/min; detection wavelength: 220nm; column temperature: 30°C, use UV detector to detect; use GPC software to process data. By substituting the chromatographic data of the sample into the calibration curve equation for calculation, the peptide molecular weight of the sample and its distribution range can be obtained. The relative percentages of components in different molecular weight ranges can be calculated using the peak area normalization method.

Table 1 Examples and Comparative Examples 1-4 provide physical and chemical indicators and yields of sericin peptides

According to Table 1, it can be seen that the sericin peptide provided in the embodiment has a higher peptide content, a lower proportion of components with a relative molecular weight of less than 1000, and, compared with existing silk fibroin peptide or silk peptide products, the free amino acid content is lower. Conducive to human body absorption.

(2) Detect the moisturizing properties of the sericin peptides provided in Examples and Comparative Examples 1-4. The detection method is as follows:

Ammonium sulfate (NH ₄ ) ₂ SO ₄ (analytical grade, Shanghai Reagent Factory No. 1) was dissolved in water to prepare a saturated ammonium sulfate (NH ₄ ) ₂ SO ₄ aqueous solution, which was placed in an empty dryer to simulate relative humidity (RH). 81% environment. The sample to be tested was prepared into an aqueous solution with a mass concentration of 2%. Pure water, 2% serine, 2% glycerol, 5% glycerol, and 0.5% HA were used as the control group. The samples were weighed and recorded as W ₀ . Pipette 200 μL and add to the patch. In a watch glass with 3M tape, weigh the mass after 4h and 8h respectively. The weight is recorded as W _n . According to the formula moisture retention rate (%) = (W _n -W ₀ )÷W ₀ *100%, the moisture retention is calculated Rate; the experimental results are expressed as mean ± standard deviation, and Tukey's Method is used for data analysis. p<0.05 means there is a significant difference, and the significant letter marking method is used. Those with the same letter mean there is no significant difference, and there is no significant difference. Those with the same letters have significant differences. The test results are shown in Figure 2.

As shown in Figure 2, in an environment with relative humidity (R.H.) of 81%, left for 4h and 8h, using pure water as a negative control, the moisturizing rate of the sericin peptide provided in the embodiment is the same as that of pure water and Comparative Examples 1-4 There are significant differences, and the moisturizing rate of the sericin peptide of the embodiment is higher than that of glycerol at the same concentration, but the difference is not significant with the same concentration of serine, 2% and 5% glycerol, and 0.5% HA, which shows that, The sericin peptide provided in the embodiment has the same moisturizing effect as 2% serine solution, 2% glycerin, 5% glycerin and 5% HA.

(3) Identify the characteristic structures of the sericin peptides provided in Examples and Comparative Examples 1-4. The identification method is as follows:

Accurately weigh 20.0mg of GGS, AS and GS standard powders respectively (all purchased from Suzhou Qiangyao Biotechnology Co., Ltd., purity ≥98%), add water to dissolve, vortex to mix, adjust the volume to 100mL, and prepare 200μg/ mL of standard stock solution. Take 500 μL of the above standard stock solution and adjust the volume to 10 mL to obtain a mixed standard intermediate working solution of 10 μg/mL. The above mixed standard intermediate working solution was gradually diluted with pure water to a series of standard working solutions of 1.95, 3.91, 7.81, 15.63, 31.25, 62.5, 125, 250 and 500ng/mL.

Use pure water to prepare the peptide sample to 20.0 mg/mL, dilute it 10 ³ times with pure water, and prepare for testing.

An ultra-high performance liquid chromatograph Nexera 20AC column oven, CBM-20A system controller, LCMS-8060 triple quadrupole mass spectrometer, LabSolutionsVer.5.91 chromatography workstation. XS205DU analytical balance (Mettler Toledo, USA); QL-901 vortex mixer (Qilin Bell Instrument Manufacturing Co., Ltd., China).

Liquid chromatography conditions: Chromatographic column: InertsilODS-3 (5μm, 2.1*250mm); mobile phase: A is 0.1% formic acid aqueous solution, B is 0.1% formic acid acetonitrile solution; gradient elution program: 0-15min B0-50%; 15 -20minB50-100%; 20-25minB100%; 25.1-35minB0%; flow rate: 0.2mL/min; injection volume: 5μL; column temperature: 40°C.

Mass spectrometry conditions: ionization mode: ESI, positive ion mode; ion spray voltage: +4.5kV; atomizing gas flow rate: nitrogen 3.0L/min; heating gas flow rate: nitrogen 10L/min; drying gas flow rate: nitrogen 10L/min; DL temperature: 250℃; heating module temperature: 400℃; ion source temperature: 300℃; scanning mode: multiple reaction monitoring (MRM); dwell time: 100ms; delay time: 3ms; MRM parameters: see Table 2.

Table 2 MRM optimization parameters of standard products

* indicates quantitative ion

Figures 3a to 5b are respectively the chromatographic detection results and standard curves of GGS, AS and GS standards. Figures 6a to 10c are respectively the chromatograms of the characteristic peptides in the sericin peptides provided in Examples and Comparative Examples 1-4. The test results, according to Figures 3a-10c, show that the Examples and Comparative Examples 1-3 all contain three characteristic peptides, while Comparative Example 4 only contains trace amounts of the characteristic peptides GGS and GS. The values of each group of silk were calculated based on the standard curve. The content of characteristic structures in collagen peptides, the calculation results are shown in Table 3.

Table 3 Contents of three characteristic peptides in Examples and Comparative Examples 1-4

	GGSGGS	ASAS	GSGS
实施例Example	0.84％0.84%	0.20％0.20%	0.51％0.51%
对比例1Comparative example 1	0.69％0.69%	0.17％0.17%	0.51％0.51%
对比例2Comparative example 2	0.75％0.75%	0.18％0.18%	0.47％0.47%
对比例3Comparative example 3	0.72％0.72%	0.16％0.16%	0.43％0.43%
对比例4Comparative example 4	0.01％0.01%	0.00％0.00%	0.01％0.01%

According to Table 3, it can be seen that compared with Comparative Examples 1-4, the sericin peptide provided in the Examples has three characteristic peptide segments GGS, AS and GS at the same time, and the content is significantly better than Comparative Examples 1-4, indicating that according to the Example The preparation method provided can effectively enzymatically hydrolyze silk protein and effectively obtain three characteristic peptides GGS, AS and GS.

(4) Evaluate the functions of the characteristic structures of the sericin peptides provided in Examples and Comparative Examples 1-4. The evaluation method is as follows:

The three characteristic peptide standards of GGS, AS, and GS and the sericin peptide provided in the examples were prepared into a 0.4% aqueous solution, and the moisturizing function evaluation method provided in Part (2) was used to conduct the moisturizing rate test. The test results are shown in Figure 11 Show.

As shown in Figure 11, using pure water as a negative control, the sericin peptide provided in the example has a certain moisturizing function, and the changes in the moisturizing rate of the sericin peptide and the peptide segments GGS, AS, and GS after being placed for 4 hours and 8 hours The trends are consistent, indicating that the preparation method provided in this example well retains the three peptide segments GGS, AS, and GS in silk protein, so that they have corresponding moisturizing functions.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or substitutions do not deviate from the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present application. scope.

Claims

A sericin peptide with moisturizing function, wherein the sericin peptide composition at least includes peptide segments GGS, AS and GS;

Based on the mass of the sericin peptide, the content of the peptide GGS is ≥0.80%, the content of the peptide AS is ≥0.20%, and the content of the peptide GS is ≥0.50%.
The sericin peptide according to claim 1, wherein the protein content in the sericin peptide is ≥85%, the content of free amino acids is ≤5%, the content of acid-soluble protein is ≥80%, and the relative molecular weight is less than 1000. The content is ≥85%.
The sericin peptide according to claim 1 or 2, wherein the sericin peptide is made from pupa-free silkworm cocoons and is obtained by sequentially undergoing sericin dissolution, fermentation, enzymatic hydrolysis, adsorption decolorization, and drying. ;

Wherein, the fermentation uses Candida prion;

The enzymatic hydrolysis includes using alkaline protease and neutral protease for enzymatic hydrolysis.
A method for preparing sericin peptide according to any one of claims 1-3, which includes the following steps:

1) Dissolve the sericin in the pupa-free silkworm cocoons to obtain a sericin solution;

2) Use Candida utilis to ferment the sericin solution. After the fermentation is completed, a sericin fermentation liquid is obtained;

3) Add alkaline protease and neutral protease to the sericin fermentation broth for enzymatic hydrolysis. After the enzymatic hydrolysis is completed, a sericin hydrolyzate is obtained;

4) Add activated carbon to the sericin hydrolyzate for adsorption and decolorization. After the treatment, collect the filtrate and dry the filtrate to obtain the sericin peptide.
The preparation method according to claim 4, wherein step 1) specifically includes: mixing pupa-free silkworm cocoons with pure water according to a mass ratio of 1:10-30, and processing at 110-125°C for 10-90 minutes, so that the The sericin in the pupa-free silkworm cocoons is dissolved to obtain the sericin solution.
The preparation method according to claim 4, wherein the number of colonies of Candida utilis is 10 5 -10 7 based on each gram of the pupa-free silkworm cocoon.
The preparation method according to claim 4 or 6, wherein the temperature of the fermentation is 28-32°C and the time is 36-72h.
The preparation method according to claim 4, wherein, based on each gram of the pupa-free silkworm cocoon, the enzyme activity of the alkaline protease is 3000-6000U, and the enzyme activity of the neutral protease is 500-1500U.
The preparation method according to claim 4 or 8, wherein the enzymatic hydrolysis temperature is 45-55°C and the time is 4-6h.
Application of the sericin peptide according to any one of claims 1 to 3 in moisturizing products.