A mask containing extract of white-backed caterpillar and a preparation method thereof

Abstract

The application belongs to the technical field of cosmetic processing, and discloses a face mask containing extract of white muscardine moth and a preparation method thereof. The face mask comprises the following components in parts by mass: 3-10 parts of extract of white muscardine moth, 2-5 parts of nicotinamide, 0.5-3 parts of tranexamic acid, 0.5-3 parts of acetylchitose, 2-20 parts of humectant, 0.02-1 part of thickening agent, and 0.1-1.5 parts of preservative; wherein the extract of white muscardine moth is pre-stabilized extract of white muscardine moth, which comprises 40-80 parts of concentrated extract of white muscardine moth, 5-25 parts of butanediol, 0.5-5 parts of trehalose, 0.1-3 parts of hydroxypropyl cyclodextrin, 0.02-0.30 parts of sodium phytate, and 0.10-1.00 parts of sodium citrate. The extract of white muscardine moth is pre-stabilized, which is beneficial to control trace metal ions, pH, protein or polypeptide aggregation and residual odor substances before the extract enters the face mask system containing various active ingredients.

Description

Technical Field

[0001] This invention belongs to the field of cosmetic processing technology, specifically relating to a facial mask containing extracts of silkworm pupae and its preparation method. Background Technology

[0002] White silkworm is the dried body formed after silkworms are infected with Beauveria bassiana. Its extract contains water-soluble proteins, polypeptides, amino acids and other soluble components, and has the potential to be used as a skin conditioning ingredient in cosmetics.

[0003] However, crude extracts of *Bombyx mori* obtained directly through water extraction, enzymatic hydrolysis, or fermentation typically contain high-molecular-weight proteins, lipids, pigments, suspended particles, colloids, and volatile odor-causing substances. These substances may cause the extract to appear yellowish-brown or brownish-yellow, and may exhibit darkening of color, turbidity, flocculation, precipitation, or an enhanced odor during storage.

[0004] Simple filtration can usually only remove larger particles and is difficult to effectively remove soluble high molecular weight proteins, colloids and small molecule odor substances; although activated carbon or adsorption resin alone can reduce color and odor, it may also cause a large loss of water-soluble peptides, amino acids and other components; ultrafiltration alone is difficult to reduce low molecular weight pigments, salts and volatile odor substances at the same time.

[0005] In skin whitening and spot-fading cosmetics, niacinamide, tranexamic acid, and acetylglucosamine are all mature active ingredients that can be used in aqueous systems. When these active ingredients are compounded with animal-derived extracts containing proteins, peptides, inorganic salts, and trace metal ions, the ionic strength, pH, oxidation state, and colloidal balance of the system may change, leading to problems such as color changes, viscosity shifts, turbidity, precipitation, or a decrease in the content of active ingredients.

[0006] Existing technologies typically focus on obtaining silkworm extract, a certain decolorization or filtration process, or directly adding silkworm extract to cosmetics. They lack a complete solution for the phased treatment of lipid odor precursors, high molecular weight proteins, pigments, small molecule odor substances and inorganic salts of silkworm extract, and for the synergistic formulation of the obtained extract with specific pre-stabilizing materials and a variety of mature whitening active ingredients.

[0007] Therefore, how to reduce the color, odor, turbidity, and precipitation tendency of the extract while retaining as many water-soluble peptides and amino acid components as possible, and how to establish a pre-stabilization system and mask formulation process that matches the treated *Bombyx mori* extract so that it can coexist stably with nicotinamide, tranexamic acid, and acetylglucosamine in an aqueous mask system, are problems that need to be solved in this field. Summary of the Invention

[0008] The purpose of this invention is to provide a facial mask containing *Bombyx mori* extract and its preparation method, in order to solve the problem of how to reduce the color, odor, turbidity and precipitation tendency of the extract while retaining as much water-soluble polypeptide and amino acid components as possible, and to establish a pre-stabilization system and facial mask formulation process that matches the treated *Bombyx mori* extract, so that it can coexist stably with niacinamide, tranexamic acid and acetylglucosamine in an aqueous facial mask system.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: On the one hand, the present invention provides a facial mask containing silkworm extract, which, by weight, includes 3-10 parts of silkworm extract, 2-5 parts of niacinamide, 0.5-3 parts of tranexamic acid, 0.5-3 parts of acetylglucosamine, 2-20 parts of moisturizer, 0.02-1 part of thickener, and 0.1-1.5 parts of preservative.

[0010] The extract of *Bombyx mori* is a pre-stabilized extract of *Bombyx mori*, which includes 40-80 parts of concentrated extract of *Bombyx mori*, 5-25 parts of butylene glycol, 0.5-5 parts of trehalose, 0.1-3 parts of hydroxypropyl cyclodextrin, 0.02-0.30 parts of sodium phytate, and 0.10-1.00 parts of sodium citrate.

[0011] In this invention, sodium phytate, citrate buffer, trehalose, hydroxypropyl cyclodextrin, and butylene glycol are introduced into the mask composition through pre-stabilization of *Bombyx mori* extract, forming part of the mask formulation technology. Specifically, sodium phytate reduces the promoting effect of trace metal ions on the oxidation and color change of the extract; citric acid and sodium citrate form a weakly acidic buffer environment; trehalose reduces the aggregation tendency of water-soluble proteins and peptides in the extract under conditions of temperature and ionic strength changes; hydroxypropyl cyclodextrin forms an inclusion complex with some residual hydrophobic odor substances and color precursors; and butylene glycol improves the dispersion uniformity and low-temperature flowability of the premixed system.

[0012] Preferably, the content of nicotinamide is 3-4 parts, the content of tranexamic acid is 1-2 parts, and the content of acetylglucosamine is 0.8-2 parts.

[0013] Preferably, the moisturizer is one or more of glycerin, butylene glycol, propylene glycol, 1,3-propanediol, pentanediol, betaine, trehalose, and sodium hyaluronate.

[0014] Preferably, the thickener is one or more of hydroxyethyl cellulose, xanthan gum, hydroxypropyl methylcellulose, carbomer, and acrylic polymers.

[0015] More preferably, the thickener includes hydroxyethyl cellulose and xanthan gum, with the mass ratio of hydroxyethyl cellulose to xanthan gum being 2:1 to 8:1.

[0016] Preferably, the composition further includes 0 to 1 part of betaine, 0 to 0.2 part of sodium hyaluronate, and 0 to 0.3 part of allantoin.

[0017] Preferably, the preservative is one or more of phenoxyethanol, ethylhexylglycerin, 1,2-hexanediol, p-hydroxyacetophenone, and capryloyl hydroxamic acid.

[0018] Preferably, the pre-stabilized silkworm extract is prepared by the following method: S1. Remove impurities from the raw material of white silkworm and crush it. Then, perform low-temperature degreasing treatment with ethanol solution. After solid-liquid separation, remove the ethanol from the solid material to obtain degreased white silkworm raw material. S2. Mix defatted silkworm pupae raw material with an aqueous extraction medium and extract at 30-60℃ to obtain silkworm pupae extract mixture; S3. The mixture of extracts from *Bombyx mori* is subjected to coarse filtration, centrifugation, and microfiltration to obtain the primary filtrate of *Bombyx mori*. S4. Use an ultrafiltration membrane with a molecular weight cutoff of 3-30 kDa to perform ultrafiltration on the primary filtrate of *Bombyx mori* and collect the ultrafiltration permeate. S5. Contact the ultrafiltration permeate with the macroporous adsorption resin and collect the effluent after resin treatment. S6. The effluent is concentrated and washed using a nanofiltration membrane with a molecular weight cutoff of 150-1000 Da, and the nanofiltration retentate is collected. S7. Add sodium phytate, citrate buffer, trehalose, hydroxypropyl cyclodextrin and butylene glycol to the nanofiltration retentate, adjust the pH and filter to obtain pre-stabilized silkworm extract.

[0019] Preferably, in S1, the raw material of white silkworm is pulverized to 20-100 mesh.

[0020] Preferably, in S1, the mass ratio of ethanol solution to silkworm pupae raw material is 2:1 to 10:1.

[0021] Preferably, in S1, the temperature of the low-temperature degreasing treatment is 20-30°C, the number of treatments is 1-3, and the treatment time for each treatment is 30-90 minutes.

[0022] Preferably, in S1, the solid material after solid-liquid separation is subjected to vacuum drying or desolventizing under reduced pressure at a temperature not exceeding 50°C.

[0023] Preferably, in S2, the mass ratio of defatted white silkworm raw material to aqueous extraction medium is 1:5 to 1:30.

[0024] Preferably, in S2, the aqueous extraction medium is purified water or an aqueous buffer solution with a pH of 5.0 to 8.0.

[0025] Preferably, in S2, the extraction temperature is 40–50°C, the extraction time is 1.5–3 hours, and the pH of the extraction system is 5.8–6.8.

[0026] Preferably, S3 includes sequentially performing 100-300 mesh filtration, 3000-10000×g centrifugation, 1-5 μm filtration, and 0.2-0.8 μm microporous filtration.

[0027] Preferably, in step S4, an ultrafiltration membrane with a molecular weight cutoff of 5–20 kDa is used.

[0028] Preferably, in S4, the ultrafiltration temperature is 15–35°C and the transmembrane pressure is 0.05–0.40 MPa.

[0029] Preferably, in S5, a non-polar, weakly polar, or moderately polar macroporous adsorption resin is used.

[0030] More preferably, the macroporous adsorption resin is a weakly polar macroporous adsorption resin.

[0031] Preferably, the pH of the ultrafiltration permeate is adjusted to 4.5 to 6.8 before resin treatment.

[0032] Preferably, the resin treatment adopts a dynamic adsorption method, with a sample loading flow rate of 0.5–4 BV / h and a sample loading amount of 2–10 BV.

[0033] Preferably, in S6, a nanofiltration membrane with a molecular weight cutoff of 200 to 800 Da is used.

[0034] Preferably, in S6, the nanofiltration temperature is 15–35°C and the operating pressure is 0.4–2.0 MPa.

[0035] Preferably, in step S6, the effluent after resin treatment is first concentrated to 1 / 2 to 1 / 8 of its original volume, and then purified water equivalent to 0.5 to 4 times the volume of the concentrated effluent is added for washing and filtration.

[0036] On the other hand, the present invention also provides a method for preparing the above-mentioned whitening and spot-fading facial mask, comprising the following steps: D1. Mix water, humectant and thickener to hydrate the thickener and obtain the matrix phase; D2. Nicotinamide, tranexamic acid, and acetyl glucosamine are dissolved in a portion of water or a polyol aqueous solution to prepare a whitening active phase; D3. Cool the matrix phase to no higher than 45℃ and add the whitening active phase; D4. Continue cooling to no higher than 40℃, and add the pre-stabilized silkworm extract; D5. Add preservatives, adjust pH, mix well and defoam to obtain the effective components of the mask; D6. Combine the effective components of the mask with the mask carrier and encapsulate them to obtain the mask.

[0037] Preferably, in D1, the hydration temperature of the thickener is 60–80°C.

[0038] Preferably, in D2, the whitening active phase is prepared at a temperature of 20–45°C.

[0039] Preferably, in D3, the whitening active phase is added after the matrix phase is cooled to 35-45°C.

[0040] More preferably, in D4, a pre-stabilized silkworm extract is added at 25–35°C.

[0041] Preferably, the pH of the effective components of the mask is adjusted to 5.7–6.3.

[0042] Preferably, the mask carrier is non-woven fabric, silk fabric, cellulose membrane, bio-cellulose membrane, or other carriers suitable for sheet masks.

[0043] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses sodium phytate, citrate, trehalose, hydroxypropyl cyclodextrin and butylene glycol to prestabilize the treated silkworm extract, which helps to control trace metal ions, pH, protein or peptide aggregation and residual odor substances before the extract enters the mask system containing multiple active ingredients.

[0044] 2. This invention employs a treatment route that combines low-temperature degreasing, ultrafiltration, macroporous resin adsorption, and nanofiltration washing, which is beneficial for the separate removal or reduction of lipids, high molecular weight proteins, colloids, pigments, inorganic salts, and odor substances, avoiding insufficient treatment caused by a single decolorization or filtration step.

[0045] 3. The present invention first performs ultrafiltration and then macroporous resin treatment, which helps to reduce the impact of high molecular weight proteins and colloids on resin pores and adsorption sites; nanofiltration washing after resin treatment helps to further reduce inorganic salts, small molecule odors and other low molecular weight impurities, while reducing the loss of target water-soluble polypeptide components with low molecular weight impurities.

[0046] 4. In this invention, nicotinamide, tranexamic acid and acetylglucosamine are formulated separately into whitening active phases, and the pre-stabilized silkworm extract is added in stages at a lower temperature, which helps to reduce discoloration, turbidity, flocculation and loss of active ingredients caused by high temperature and local high concentration.

[0047] 5. The technical effects of this invention are produced by the combined effects of the silkworm extract processing technology, the quality characteristics of the extract, the pre-stabilization system, the whitening active system, the pH of the formulation, and the low-temperature staged feeding process, rather than by the simple mixing of the raw materials. Detailed Implementation

[0048] To enable those skilled in the art to better understand the present application, the technical solutions in specific embodiments of the present application will be clearly and completely described below. Unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by those skilled in the art.

[0049] Example 1 Take 1.00 kg of qualified dried white silkworms, remove impurities, crush and pass through a 60-mesh sieve.

[0050] Add 5.0 kg of 90% ethanol aqueous solution to the silkworm powder, stir at 25°C for 45 minutes, and filter. Repeat the degreasing process once under the same conditions. Combine the ethanol filtrates and process them separately. The resulting solid is vacuum dried at 40°C until the ethanol residue meets the internal control requirements.

[0051] Add 15.0 kg of purified water to the dried, defatted silkworm powder, adjust the pH of the system to 6.2 with citric acid or sodium citrate, and extract by stirring at 45°C for 2 hours.

[0052] After extraction, the solution was first filtered through a 150-mesh filter and then centrifuged at 6000×g for 15 minutes. The supernatant was then passed through a 1 μm filter cartridge and a 0.45 μm filter membrane to obtain the primary filtrate of *Bombyx mori*.

[0053] The primary filtrate of *Bombyx mori* was treated with an ultrafiltration membrane with a molecular weight cutoff of 10 kDa at 25°C, and the transmembrane pressure was controlled at 0.15–0.25 MPa. The ultrafiltration permeate was then collected.

[0054] The pH of the ultrafiltration permeate was adjusted to 5.8, and the permeate was passed through a pretreated AB-8 weakly polar macroporous adsorption resin column at a flow rate of 1.5 times the bed volume per hour, with a sample loading volume of 5 times the bed volume. The sample effluent was collected and washed with 1 times the bed volume of purified water. The sample effluent and the water wash effluent were combined.

[0055] The combined effluent was treated using a nanofiltration membrane with a molecular weight cutoff of 300 Da, with the temperature controlled at 25℃ and the operating pressure at 0.8–1.2 MPa. The solution was first concentrated to approximately one-third of its original volume, then washed twice with purified water (total volume equivalent to twice the volume of the concentrate), followed by further concentration to obtain a concentrated extract of *Bombyx mori* with a soluble solids content of 8.0%.

[0056] Pre-stabilized silkworm extract was prepared according to the following ratio: 60.00 parts of concentrated extract of *Bombyx mori*, 15.00 parts of butylene glycol, 3.00 parts of trehalose, 1.00 parts of hydroxypropyl cyclodextrin, 0.10 parts of sodium phytate, 0.50 parts of sodium citrate, and purified water to make up to 100 parts.

[0057] The mixture was stirred at 25°C for 30 minutes, and the pH was adjusted to 5.9 with citric acid. The mixture was then filtered through a 0.22 μm filter membrane to obtain the pre-stabilized silkworm extract.

[0058] The effective components of the mask are prepared according to the following formula: 6.00 parts of pre-stabilized silkworm extract, 3.50 parts of nicotinamide, 1.50 parts of tranexamic acid, 1.00 parts of acetylglucosamine, 4.00 parts of glycerin, 2.50 parts of butylene glycol, 0.50 parts of betaine, and 0.15 parts of allantoin.

[0059] Hydroxyethyl cellulose 0.18 parts, xanthan gum 0.04 parts, sodium hyaluronate 0.05 parts, phenoxyethanol 0.70 parts, ethylhexylglycerin 0.10 parts, purified water to make up to 100 parts.

[0060] Glycerin, a portion of butylene glycol, hydroxyethyl cellulose and xanthan gum were pre-dispersed and added to purified water in the main pot. The mixture was heated to 70°C and stirred until the thickener was fully hydrated. Allantoin, betaine and sodium hyaluronate were then added to obtain the matrix phase.

[0061] Take another portion of purified water, add nicotinamide, tranexamic acid and acetyl glucosamine at 35°C, and stir until completely dissolved to obtain the whitening active phase.

[0062] The matrix phase was cooled to 40°C, and the whitening active phase was added and mixed for 15 minutes. The temperature was further reduced to 32°C, and the pre-stabilized silkworm extract was slowly added. Phenoxyethanol and ethylhexylglycerin were added, and the pH was adjusted to 5.9 using citric acid and sodium citrate. The mixture was thoroughly mixed and vacuum degassed to obtain the effective components of the mask. The effective components were then filled into packaging bags containing the mask carrier and sealed to obtain the whitening and spot-fading mask of Example 1.

[0063] Example 2 The difference between this embodiment and embodiment 1 is that S4 uses an ultrafiltration membrane with a molecular weight cutoff of 20 kDa, and S6 uses a nanofiltration membrane with a molecular weight cutoff of 500 Da. The membrane is concentrated to 1 / 4 of its original volume and washed with 1.5 volumes of purified water. The remaining preparation steps are the same as in embodiment 1.

[0064] Example 3 The difference between this embodiment and Example 1 lies in the adjustment of the effective component formulation: 4.00 parts of pre-stabilized *Bombyx mori* extract, 4.00 parts of nicotinamide, 2.00 parts of tranexamic acid, 0.80 parts of acetylglucosamine, 5.00 parts of glycerol, 3.00 parts of butylene glycol, 0.30 parts of trehalose, 0.50 parts of betaine, 0.15 parts of allantoin, 0.20 parts of hydroxyethyl cellulose, 0.04 parts of xanthan gum, 0.05 parts of sodium hyaluronate, 0.70 parts of phenoxyethanol, and 0.10 parts of ethylhexylglycerin, with purified water added to a total of 100 parts. The preparation was carried out according to the phase separation, low temperature, and staged feeding method of Example 1, with the final pH adjusted to 6.2. The remaining steps were the same as in Example 1.

[0065] Comparative Example 1 This comparative example follows the steps of Example 1, involving gentle water extraction, coarse filtration, centrifugation, and microfiltration to obtain a primary filtrate of *Bombyx mori*, but without ultrafiltration, macroporous resin adsorption, nanofiltration washing, or pre-stabilization treatment. The primary filtrate of *Bombyx mori* is used to replace the pre-stabilized *Bombyx mori* extract in Example 1, based on the principle of equal soluble solids. The remaining mask formulation and preparation method are the same as in Example 1, resulting in the mask of Comparative Example 1.

[0066] Comparative Example 2 In this comparative example, the primary filtrate of *Bombyx mori* was treated with 10 kDa ultrafiltration and macroporous adsorption resin according to the method of Example 1, but without nanofiltration concentration and washing. The effluent after resin treatment was concentrated at low temperature to the same soluble solids content as the *Bombyx mori* extract concentrate of Example 1, and then processed according to the pre-stabilization formula of Example 1. The obtained pre-stabilized extract was added to the mask formula of Example 1 according to the principle of equal soluble solids, and the other conditions were the same as in Example 1.

[0067] Comparative Example 3 This comparative example follows the method of Example 1, performing low-temperature defatting, gentle extraction, solid-liquid separation, ultrafiltration, macroporous resin adsorption, and nanofiltration washing to obtain a concentrated extract of *Bombyx mori*. However, instead of adding sodium phytate, sodium citrate, trehalose, hydroxypropyl cyclodextrin, and butylene glycol for pre-stabilization, the concentrated extract is directly added to the mask formulation of Example 1 according to the principle of equal amounts of soluble solids. The remaining formulation and low-temperature addition conditions are the same as in Example 1, resulting in the mask of Comparative Example 3.

[0068] Comparative Example 4 In this comparative example, the *Bombyx mori* raw material was subjected to low-temperature defatting, gentle extraction, coarse filtration, centrifugation, and microfiltration according to the method of Example 1 to obtain the primary filtrate of *Bombyx mori*. However, the primary filtrate of *Bombyx mori* was first treated with macroporous adsorption resin and then subjected to ultrafiltration.

[0069] Specifically, the pH of the primary filtrate of *Bombyx mori* was adjusted to 5.8, and it was passed through the same AB-8 type macroporous adsorption resin column as in Example 1 at a flow rate of 1.5 times the bed volume per hour. The sample loading was controlled according to the principle that the same amount of resin was used for each unit of soluble solids in the primary filtrate of *Bombyx mori*. The sample effluent and the water washing effluent of 1 times the bed volume of purified water were collected.

[0070] The combined resin effluent was treated at 25°C using an ultrafiltration membrane with a molecular weight cutoff of 10 kDa, with the transmembrane pressure controlled at 0.15–0.25 MPa, and the ultrafiltration permeate was collected.

[0071] Subsequently, a nanofiltration membrane with a molecular weight cutoff of 300 Da was used for concentration and washing. The nanofiltration temperature, operating pressure, concentration factor, and washing volume were the same as in Example 1, yielding a concentrated extract of *Bombyx mori*.

[0072] Butylene glycol, trehalose, hydroxypropyl cyclodextrin, sodium phytate, sodium citrate, and citric acid were added according to the proportions in Example 1 for pre-stabilization treatment. The soluble solids were then added to the mask formulation of Example 1 in equal amounts. The remaining formulation and preparation steps were the same as in Example 1, resulting in the mask of Comparative Example 4.

[0073] Comparative Example 5 This comparative example uses the pre-stabilized *Bombyx mori* extract prepared in Example 1, and employs the same active ingredient formulation as in Example 1. However, while maintaining the matrix phase temperature at 60°C, the whitening active phase, pre-dissolved in nicotinamide, tranexamic acid, and acetylglucosamine, and the pre-stabilized *Bombyx mori* extract are sequentially added to the matrix phase, with an interval of no more than 5 minutes between additions. Stirring continues at 60°C for 30 minutes, followed by cooling. Phenoxyethanol and ethylhexylglycerin are then added, and the pH is adjusted to 5.9 using citric acid and sodium citrate. The mixture is thoroughly mixed and degassed under vacuum to obtain the active ingredient formulation for Comparative Example 5. The active ingredient formulation is then filled into packaging bags containing a mask carrier and sealed to obtain the mask of Comparative Example 5.

[0074] Test Example 1 This test example evaluates the effects of omitting nanofiltration washing, omitting pre-stabilization treatment, changing the order of ultrafiltration and macroporous adsorption resin treatment, or omitting complete purification treatment during the preparation of *Bombyx mori* extract on the color, transmittance, turbidity, conductivity, odor, soluble solids recovery rate, total peptide retention rate, and molecular weight distribution of the obtained *Bombyx mori* extract. *Bombyx mori* extracts prepared in Example 1 and Comparative Examples 1-4 were used, with all samples prepared from the same batch of *Bombyx mori* raw material. Except for the process steps investigated, the amounts of raw materials, extraction conditions, membrane treatment conditions, resin dosage, concentration factor, and pre-stabilization conditions were kept consistent.

[0075] Furthermore, since some samples contain pre-stabilized components, to avoid interference from added components on the soluble solids content and detection results, each sample was normalized according to the soluble solids content derived from *Bombyx mori*. Based on the material input amount, concentration factor, and measured soluble solids content during the preparation process, the soluble solids content of each sample was calculated. Each sample was then diluted with purified water to a soluble solids content of 1.0% for color, transmittance, turbidity, odor, and molecular weight distribution detection. Total peptide retention and soluble solids recovery were calculated based on the actual sample volume and concentration of each process batch, not on the diluted concentration.

[0076] Specifically, the test items and test methods are as follows: Color detection: Using a UV-Vis spectrophotometer with purified water as a blank, the absorbance (A420) of each sample at 420 nm was measured. The L*, a*, and b* values ​​of each sample were measured using a colorimeter, and the color difference ΔE was calculated using sample B as a reference. The decolorization rate relative to sample B was calculated using the following formula: Decolorization rate = (A420 of sample B - A420 of the sample to be tested) ÷ A420 of sample B × 100%.

[0077] Transmittance and turbidity detection: The transmittance of each sample at 600 nm was measured using a spectrophotometer. The turbidity of each sample was measured using a turbidimeter, and the results are expressed as NTU.

[0078] Conductivity measurement: The conductivity of each sample was measured using a calibrated conductivity meter under the same temperature conditions, and the results are expressed in μS / cm. Conductivity is mainly used to evaluate the removal efficiency of nanofiltration washing for inorganic salts and other small molecule ionic substances that can permeate the nanofiltration membrane.

[0079] Odor evaluation: A blind evaluation shall be conducted by no fewer than 5 uniformly trained evaluators, and scores shall be given according to the following criteria: 0 points: No identifiable special odor; 1 point: Very slight special odor; 2 points: Slight but identifiable special odor; 3 points: Obvious special odor; 4 points: Strong special odor; 5 points: Strong special odor. The average score from all evaluators is taken.

[0080] Soluble solids recovery rate: The volume and soluble solids content of the samples before and after each process treatment were determined, and the soluble solids recovery rate was calculated according to the following formula: Soluble solids recovery rate = (Total mass of soluble solids from *Bombyx mori* in the treated sample / Total mass of soluble solids in the primary filtrate of *Bombyx mori*) × 100%. Butylene glycol, trehalose, hydroxypropyl cyclodextrin, sodium phytate, and citrate added during the pre-stabilization treatment are not included in the soluble solids from *Bombyx mori*.

[0081] Total peptide content and total peptide retention rate: The total peptide content of each sample was determined using the o-phthalaldehyde method. The total mass of total peptides in each sample was calculated based on the sample volume and total peptide concentration, and the total peptide retention rate was calculated using the following formula: Total peptide retention rate = Total mass of total peptides in the treated sample / Total mass of total peptides in the primary filtrate of *Bombyx mori* × 100%.

[0082] Molecular weight distribution: The molecular weight distribution of water-soluble components in each sample was determined using gel permeation chromatography, size exclusion high-performance liquid chromatography, or a validated equivalent method. The relative proportions of at least the following molecular weight ranges should be recorded: components greater than 10 kDa; components from 0.3 to 10 kDa; and components less than 0.3 kDa.

[0083] The test results are shown in the table below: Table 1: Summary of Quality Test Results of Silkworm Extracts After Different Processing Techniques

[0084] Note: Example 2 is the primary filtrate of *Bombyx mori* without subsequent purification treatment, serving as a benchmark for comparison among various treatment processes. The relative retention rates of soluble solids and total peptides were not calculated and are indicated by "—" in the table.

[0085] The results showed that ultrafiltration mainly reduced the high molecular weight components and turbidity in the primary filtrate of *Bombyx mori*, with the >10 kDa component decreasing from 27.5% to 7.8%, but its improvement on color and odor was relatively limited. After treatment with macroporous adsorption resin, A420 decreased from 0.681 to 0.316, and the odor score decreased from 3.8 to 2.2, indicating that the resin treatment mainly played a role in decolorization and deodorization. After further nanofiltration washing, the sample conductivity decreased from 1295 μS / cm to 438 μS / cm, turbidity and odor continued to decrease, while the proportion of 0.3–10 kDa components increased to 72.1%. Compared with the unfiltered sample, the total peptide retention rate of the nanofiltration-washed sample was only slightly reduced, but the color, turbidity, odor and conductivity were further improved, indicating that nanofiltration washing can improve the overall usability of the extract without excessive loss of total peptides. The color and turbidity of the sample did not increase significantly after pre-stabilization treatment, while the odor score decreased slightly, indicating that the pre-stabilization material did not have a significant adverse effect on the appearance of the extract.

[0086] Test Example 2 This test example examines the stability and active ingredient retention rate of the face mask. The effective components of the face masks prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to the following stability tests: Store at 40℃ for 12 weeks; alternate between 4℃ and 45℃, maintaining each temperature for 24 hours, for a total of 6 cycles.

[0087] Appearance, color, odor, pH, viscosity, transmittance, turbidity, and precipitation were measured at the beginning of the experiment and at weeks 2, 4, 8, and 12.

[0088] The contents of nicotinamide, tranexamic acid and acetylglucosamine were determined by liquid chromatography, and the retention rate of active ingredients was calculated by the following formula: Retention rate of active ingredients = Content of active ingredients after storage / Initial content of active ingredients × 100%.

[0089] The ΔE before and after storage was measured using a colorimeter; the viscosity was measured using a rotational viscometer under the same temperature, rotor, and rotation speed conditions.

[0090] The test results are shown in Tables 2 and 3: Table 2: Summary of stability test results of active ingredients in face masks after 12 weeks of storage at 40℃

[0091] The results showed that none of Examples 1-3 exhibited significant stratification after 12 weeks of storage at 40℃, with relatively small changes in color, pH, and viscosity. The retention rates of the three whitening active ingredients were all above 95%. Among them, Example 1 showed relatively good overall stability, indicating that the combination of 10 kDa ultrafiltration, 300 Da nanofiltration, pre-stabilization treatment, and low-temperature staged feeding had good compatibility.

[0092] Comparative Example 1 used untreated primary filtrate of *Bombyx mori*, which showed significant discoloration, turbidity, decreased viscosity, and precipitation after storage, indicating that simple solid-liquid separation is insufficient to stably apply *Bombyx mori* extract in whitening systems. Comparative Example 2, without nanofiltration washing, showed better stability than Comparative Example 1, but still exhibited a significant increase in turbidity and a small amount of precipitation, indicating that low-molecular-weight impurities, inorganic salts, and high conductivity can adversely affect long-term stability. Comparative Example 3, although using complete membrane separation and resin treatment, did not undergo pre-stabilization, and its color, turbidity, and viscosity changes were greater than in Example 1, indicating that the pre-stabilization system composed of sodium phytate, citrate, trehalose, hydroxypropyl cyclodextrin, and butylene glycol helps control the aggregation of metal ions, pH, and water-soluble components. Comparative Example 4's stability fell between that of Example 1 and Comparative Example 2, demonstrating a certain technical advantage in supporting specific ultrafiltration and resin treatment sequences. Comparative Example 5, which simultaneously added the active ingredient and the extract of *Bombyx mori* at high temperature, showed that the retention rate of the active ingredient and the appearance stability were both lower than those of Example 1. This indicates that low temperature and staged feeding are not simply production operation choices, but rather technical conditions that affect the stability of the system.

[0093] Table 3: Summary of Stability Test Results of Effective Components in Facial Masks After Temperature Cycling

[0094] The results showed that the trend of temperature cycling was basically consistent with that of long-term storage at 40℃. Examples 1-3 maintained a relatively uniform appearance under cycling conditions, with a centrifugal sedimentation rate not exceeding 0.10 parts. Comparative Example 1 showed a significantly higher freeze-thaw turbidity and centrifugal sedimentation rate, indicating that high-molecular-weight proteins, colloids, and lipids in the crude extract are prone to aggregation under temperature changes. While Comparative Examples 2-5 were superior to Comparative Example 1, their stability was lower than that of Example 1, further demonstrating that nanofiltration, pre-stabilization, a specific treatment sequence, and low-temperature staged feeding all contribute to the stability of the *Bombyx mori* extract facial mask system.

[0095] Test Example 3 This test case evaluates the impact of feeding temperature and staged feeding method on the initial quality of the effective components of the film during the production stage, based on Example 1 and Comparative Example 5. The test items and methods are as follows: Initial A420: measured using a UV-Vis spectrophotometer; initial turbidity: measured using a turbidimeter; initial pH: measured using a calibrated pH meter.

[0096] Initial recovery rates of active ingredients: The actual contents of nicotinamide, tranexamic acid, and acetylglucosamine were determined by high-performance liquid chromatography (HPLC). The initial recovery rates of each active ingredient were calculated using the following formula: Initial recovery rate = Measured content of active ingredients in the effective components of the mask ÷ Theoretical content calculated based on the actual amount of material fed × 100%.

[0097] The test results are shown in Table 4: Table 4: Initial Indicators of Effective Components in Facial Masks Obtained Through Different Addition Processes

[0098] The results showed that, under identical formulation conditions, Comparative Example 5, after being added and kept at 60°C, had higher initial A420 and turbidity than Example 1, and its initial recovery rate of the three whitening active ingredients was also slightly lower. This indicates that some color changes, colloidal aggregation, and loss of active ingredients may occur during the production stage, rather than all occurring during subsequent storage. Adding the whitening active phase and the pre-stabilized *Bombyx mori* extract at lower temperatures helps mitigate the impact of high-temperature treatment on the initial state of the system.

[0099] Finally, it should be noted that the described embodiments are merely some, not all, of the embodiments of the present invention. Those skilled in the art will understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents; that is, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A facial mask containing extract of *Bombyx mori*, characterized in that, By weight, it includes the following components: 3-10 parts of silkworm extract, 2-5 parts of nicotinamide, 0.5-3 parts of tranexamic acid, 0.5-3 parts of acetylglucosamine, 2-20 parts of humectant, 0.02-1 part of thickener, and 0.1-1.5 parts of preservative; The extract of *Bombyx mori* is a pre-stabilized extract of *Bombyx mori*, which includes 40-80 parts of concentrated extract of *Bombyx mori*, 5-25 parts of butylene glycol, 0.5-5 parts of trehalose, 0.1-3 parts of hydroxypropyl cyclodextrin, 0.02-0.30 parts of sodium phytate, and 0.10-1.00 parts of sodium citrate.

2. The facial mask according to claim 1, characterized in that, The moisturizer is one or more of the following: glycerin, butylene glycol, propylene glycol, 1,3-propanediol, pentanediol, betaine, trehalose, and sodium hyaluronate.

3. The facial mask according to claim 1, characterized in that, The thickener is one or more of hydroxyethyl cellulose, xanthan gum, hydroxypropyl methylcellulose, carbomer, and acrylic polymers.

4. The facial mask according to claim 1, characterized in that, It also includes one of the following: 0-1 parts betaine, 0-0.2 parts sodium hyaluronate, and 0-0.3 parts allantoin.

5. The facial mask according to claim 1, characterized in that, Pre-stabilized *Bombyx mori* extract was prepared by the following method: S1. Remove impurities from the raw material of white silkworm and crush it. Then, perform low-temperature degreasing treatment with ethanol solution. After solid-liquid separation, remove the ethanol from the solid material to obtain degreased white silkworm raw material. S2. Mix defatted silkworm pupae raw material with an aqueous extraction medium and extract at 30-60℃ to obtain silkworm pupae extract mixture; S3. The mixture of extracts from *Bombyx mori* is subjected to coarse filtration, centrifugation, and microfiltration to obtain the primary filtrate of *Bombyx mori*. S4. Use an ultrafiltration membrane with a molecular weight cutoff of 3-30 kDa to perform ultrafiltration on the primary filtrate of *Bombyx mori* and collect the ultrafiltration permeate. S5. Contact the ultrafiltration permeate with the macroporous adsorption resin and collect the effluent after resin treatment. S6. The effluent is concentrated and washed using a nanofiltration membrane with a molecular weight cutoff of 150-1000 Da, and the nanofiltration retentate is collected. S7. Add sodium phytate, citrate buffer, trehalose, hydroxypropyl cyclodextrin and butylene glycol to the nanofiltration retentate, adjust the pH and filter to obtain pre-stabilized silkworm extract.

6. The facial mask according to claim 5, characterized in that, In S1, the mass ratio of ethanol solution to silkworm raw material is 2:1 to 10:1; the temperature of low-temperature degreasing treatment is 20 to 30°C, the number of treatments is 1 to 3, and the treatment time for each treatment is 30 to 90 minutes.

7. The facial mask according to claim 5, characterized in that, In S2, the mass ratio of defatted white silkworm raw material to aqueous extraction medium is 1:5 to 1:30; the extraction temperature is 40 to 50℃; the extraction time is 1.5 to 3 hours; and the pH of the extraction system is 5.8 to 6.

8.

8. The facial mask according to claim 5, characterized in that, S3 includes sequential filtration of 100–300 mesh, centrifugation of 3000–10000×g, filtration of 1–5 μm, and filtration of 0.2–0.8 μm micropores.

9. The facial mask according to claim 5, characterized in that, In S4, an ultrafiltration membrane with a molecular weight cutoff of 5–20 kDa is used; in S5, a non-polar, weakly polar, or moderately polar macroporous adsorption resin is used; and in S6, a nanofiltration membrane with a molecular weight cutoff of 200–800 Da is used.

10. A method for preparing a facial mask containing *Bombyx mori* extract according to any one of claims 1-9, characterized in that, Includes the following steps: D1. Mix water, humectant and thickener to hydrate the thickener and obtain the matrix phase; D2. Nicotinamide, tranexamic acid, and acetyl glucosamine are dissolved in a portion of water or a polyol aqueous solution to prepare a whitening active phase; D3. Cool the matrix phase to no higher than 45℃ and add the whitening active phase; D4. Continue cooling to no higher than 40℃, and add the pre-stabilized silkworm extract; D5. Add preservatives, adjust pH, mix well and defoam to obtain the effective components of the mask; D6. Combine the effective components of the mask with the mask carrier and encapsulate them to obtain the mask.

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