Highly stable vitamin c composition and use in whitening and anti-aging cosmetics

Abstract

The application discloses a high-stability vitamin C composition and application thereof in whitening and anti-aging cosmetics. The composition comprises a sedimentation-type vitamin C compound and an upper solution. The sedimentation-type vitamin C compound is composed of L-ascorbic acid, chitosan, a crosslinking agent and a sedimentation aid. The L-ascorbic acid is prepared through a microencapsulation and spray drying process and is subjected to coating treatment to form high-density particles. The upper solution is composed of cyclohexylsiloxane, propylene glycol, glycerol, an antioxidant, a pH regulator and a preservative. When standing, the compound is deposited at the bottom of a container, only the upper solution contacts air, and the oxidation rate of vitamin C is significantly reduced. When used, the composition is shaken and dispersed, the microcapsule structure slowly releases active ingredients when meeting skin moisture, and stability and efficacy are considered. The composition is applied to serum or emulsion, solves the problems of active ingredient loss, discoloration and turbidity caused by frequent opening of a traditional product, realizes the effects of colorless and transparent storage and efficient penetration in use, and achieves the whitening and anti-aging effects.

Description

Technical Field

[0001] This invention belongs to the field of cosmetic technology and relates to a highly stable vitamin C composition and its application in whitening and anti-aging cosmetics. Background Technology

[0002] As consumers' demands for skincare upgrade, whitening and anti-aging have become core appeals in the cosmetics market. Vitamin C (especially L-ascorbic acid), as a highly effective active ingredient, is widely used due to its multiple advantages: it can inhibit tyrosinase activity to reduce melanin deposition, achieving whitening and fading dark spots; at the same time, it can scavenge free radicals and promote collagen synthesis, playing an anti-aging and firming role. Furthermore, its source is relatively natural, it has good biocompatibility with the skin, and at reasonable concentrations, it has low irritation, making it one of the core ingredients in whitening and anti-aging cosmetics.

[0003] However, the enediol structure in vitamin C molecules is unstable, posing a significant technical bottleneck in the use of skincare products. When products are used daily by consumers, frequent opening of the cap leads to continuous exposure of the active ingredients to air. Direct contact between oxygen and vitamin C molecules accelerates their oxidative degradation. This oxidation process not only directly results in the loss of vitamin C activity but also affects the product's appearance and user experience. Summary of the Invention

[0004] The purpose of this invention is to provide a highly stable vitamin C composition and its application in whitening and anti-aging cosmetics, effectively reducing the oxidative degradation of vitamin C during storage and use.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a highly stable vitamin C composition comprising a precipitated vitamin C complex and an upper solution;

[0007] The precipitated vitamin C complex comprises the following raw materials in parts by weight: 10-12 parts L-ascorbic acid, 8-10 parts chitosan, 0.2-0.3 parts crosslinking agent, and 1.5-2.5 parts precipitating agent;

[0008] The upper solution comprises the following raw materials in parts by weight: 50-70 parts solvent, 0.6-1.0 parts antioxidant, 1.6-2.4 parts pH adjuster, and 0.5-0.9 parts preservative;

[0009] The density of the sedimented vitamin C complex is greater than the density of the upper layer solution.

[0010] Preferably, the settling agent is a mixture of magnesium aluminum silicate and silicon dioxide.

[0011] Preferably, the mass ratio of magnesium aluminum silicate to silicon dioxide is 1.5-2.5:0.2-0.5.

[0012] Preferably, the method for preparing the precipitated vitamin C complex includes the following steps:

[0013] A1. Dissolve L-ascorbic acid in an acidic buffer solution and stir in an ice bath at 0-5°C until completely dissolved to form an acidic vitamin C solution;

[0014] A2. Dissolve chitosan in acetic acid solution to form chitosan solution; then add acidic vitamin C solution dropwise to chitosan solution, and add cross-linking agent to form microcapsule suspension;

[0015] A3. The microcapsule suspension is spray-dried to obtain microcapsule dry powder.

[0016] A4. Magnesium aluminum silicate and silicon dioxide are dissolved in propylene glycol to form a coating solution. The coating solution is then sprayed onto the surface of the microcapsule dry powder using a fluidized bed coating machine to obtain a precipitated vitamin C complex.

[0017] Preferably, the solvent comprises cyclohexylsiloxane, propylene glycol, and glycerol, wherein the mass ratio of cyclohexylsiloxane, propylene glycol, and glycerol is 35-45:10-15:5-10.

[0018] Preferably, the antioxidant comprises ferulic acid and tocopheryl acetate, wherein the mass ratio of ferulic acid to tocopheryl acetate is 0.4-0.6:0.2-0.4.

[0019] Preferably, the pH adjuster comprises citric acid and sodium citrate, wherein the mass ratio of citric acid to sodium citrate is 0.8-1.2:0.8-1.2.

[0020] Preferably, the preservative comprises phenoxyethanol and behenyltrimethylammonium chloride, wherein the mass ratio of phenoxyethanol to behenyltrimethylammonium chloride is 0.4-0.6:0.1-0.3.

[0021] Preferably, the vitamin C composition is packaged in light-proof packaging material; during packaging, the upper layer solution is injected first, and then the precipitating vitamin C complex is added.

[0022] Secondly, the present invention provides the application of the highly stable vitamin C composition as described above in whitening and anti-aging cosmetics, wherein the dosage form of the cosmetic is an anhydrous serum or anhydrous emulsion.

[0023] The beneficial effects of this invention are:

[0024] (1) The present invention, through the design of a sedimentation type vitamin C complex and an upper solution, enables the complex to settle rapidly to the bottom of the container when left to stand due to its density advantage, while only the upper solution is exposed to air, reducing the contact between vitamin C and oxygen. Combined with the hydrophobic film formed by cyclohexylsiloxane in the upper solution, the oxidation rate of vitamin C can be significantly reduced. When this composition is applied to whitening and anti-aging cosmetics such as high-concentration vitamin C serums or anhydrous lotions: During product storage, even with long-term storage at room temperature, the anhydrous vitamin C serums and anhydrous creams can maintain vitamin C activity and always retain a colorless and transparent appearance without yellowing or cloudiness. During product use, consumers can shake the product to evenly disperse the settled complex. The dispersed serum or lotion remains transparent with no visible particles and feels smooth on the skin when applied. Furthermore, the microencapsulated vitamin C is slowly released upon contact with skin moisture, preventing rapid oxidation of vitamin C due to air exposure during use and ensuring the continued effectiveness of the active ingredients. This achieves the core advantages of stable storage and high efficacy during use, solving the industry pain points of traditional high-concentration vitamin C cosmetics such as "frequent opening for oxidation, discoloration during storage, and loss of activity during use."

[0025] (2) Vitamin C is encapsulated using chitosan microencapsulation technology. During the microcapsule preparation process, the activity of vitamin C is effectively protected by the dual protection of low temperature ice bath and acidic buffer solution, avoiding activity loss during the preparation process. In addition, the surface of the microcapsule is coated with magnesium aluminum silicate-silica, which can be evenly dispersed by shaking when used. Chitosan biodegrades after contact with skin moisture, ensuring that vitamin C can effectively penetrate to the skin surface when used. Detailed Implementation

[0026] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0027] Example 1

[0028] A highly stable vitamin C composition comprising a sedimenting vitamin C complex and a supernatant solution. The density of the sedimenting vitamin C complex is greater than the density of the supernatant solution.

[0029] The precipitated vitamin C complex comprises the following raw materials in parts by weight, as shown in Table 1.

[0030] Table 1

[0031] Raw material name Dosage (parts by weight) L-Ascorbic Acid 11 copies Chitosan 9 copies Crosslinking agent - 50% genipin propylene glycol solution 0.25 copies Settling aid - magnesium aluminum silicate (particle size ≤10μm) 2 copies Flocculant - Silica (Fused Silica) 0.35 copies

[0032] The upper solution comprises the following parts by weight of raw materials, as shown in Table 2.

[0033] Table 2

[0034] Raw material name Dosage (parts by weight) Solvent - Cyclohexylsiloxane 40 copies Solvent - Propylene Glycol 12 copies Solvent-glycerol 8 copies Antioxidant - Ferulic Acid 0.5 copies Antioxidant - Tocopheryl Acetate 0.3 copies pH adjuster - citric acid 1 copy pH adjuster - sodium citrate 1 copy Preservative - Phenoxyethanol 0.5 copies Preservative - behenyltrimethylammonium chloride 0.2 copies

[0035] A method for preparing a precipitated vitamin C complex includes the following steps:

[0036] A1. Add sodium dihydrogen phosphate to deionized water at a mass ratio of 9:1 (sodium hydrogen phosphate: disodium hydrogen phosphate) and adjust the pH to 3.2 to form an acidic buffer solution. Slowly add 11 parts of L-ascorbic acid to the buffer solution, place it in an ice bath at 0°C, and stir with a magnetic stirrer at 250 rpm for 10 minutes until completely dissolved to obtain an acidic vitamin C solution.

[0037] A2. Add 9 parts of chitosan to a 1% v / v acetic acid solution and stir at 25°C for 30 minutes until completely dissolved to form a 1% w / v chitosan solution (pH=4.5). Keep the solution in an ice bath at 0°C and add acidic vitamin C solution dropwise at a rate of 1 mL / min, stirring continuously at 300 rpm during the addition. After the addition is complete, add 0.25 parts of 50% genipin propylene glycol solution and continue stirring for 20 minutes to form a microcapsule suspension.

[0038] A3. Feed the microcapsule suspension into a spray dryer, set the inlet air temperature to 180℃, the outlet air temperature to 80℃, and the feed rate to 5mL / min. After drying, collect the microcapsule powder (moisture content ≤3%).

[0039] A4. Add 2 parts magnesium aluminum silicate and 0.35 parts silicon dioxide to 5 mL of propylene glycol and stir at 25°C for 20 minutes until completely dispersed to form a sedimentation aid coating solution. Feed the microcapsule dry powder into a fluidized bed coating machine, set the inlet air temperature to 60°C and the atomization pressure to 0.2 MPa, and spray the coating solution onto the surface of the microcapsule dry powder at a rate of 2 mL / min. After spraying, continue fluidized drying for 10 minutes to obtain a sedimented vitamin C complex.

[0040] The method for preparing the upper layer solution includes the following steps:

[0041] Add 40 parts of cyclohexylsiloxane, 12 parts of propylene glycol, and 8 parts of glycerol to a stirred tank, heat to 40°C, and stir with a paddle stirrer at 150 rpm for 15 minutes until the system is transparent and homogeneous. Keep the temperature constant at 40°C, and add 0.5 parts of ferulic acid and 0.3 parts of tocopheryl acetate in sequence, stirring for 5 minutes until dissolved. Then add 1 part of citric acid and 1 part of sodium citrate, and stir for 5 minutes. Finally, add 0.5 parts of phenoxyethanol and 0.67 parts of 30% behenyltrimethylammonium chloride aqueous solution (0.2 parts after purification), and stir for 10 minutes to obtain the supernatant solution.

[0042] Packaging of a highly stable vitamin C composition: A 250mL brown glass bottle (light-proof packaging material: high borosilicate glass) is used. First, 100g of the upper layer solution is injected into the bottle; then 10g of the above-mentioned precipitated vitamin C complex is added; the air in the bottle is extracted by a vacuum pump (vacuum degree -0.09MPa), and at the same time, a mixed gas of 95%N2 + 5%CO2 (purity ≥99.99%) is injected. After purging 3 times, the bottle is immediately sealed with a butyl rubber stopper and an aluminum cap and stored away from light.

[0043] Example 2

[0044] A highly stable vitamin C composition comprising a sedimenting vitamin C complex and a supernatant solution. The density of the sedimenting vitamin C complex is greater than the density of the supernatant solution.

[0045] The precipitated vitamin C complex comprises the following raw materials in parts by weight, as shown in Table 3.

[0046] Table 3

[0047] Raw material name Dosage (parts by weight) L-Ascorbic Acid 10 copies Chitosan 8 copies Crosslinking agent - 50% genipin propylene glycol solution 0.2 copies Settling aid - magnesium aluminum silicate (particle size ≤10μm) 1.5 copies Flocculant - Silica (Fused Silica) 0.2 copies

[0048] The upper solution comprises the following parts by weight of raw materials, as shown in Table 4.

[0049] Table 4

[0050] Raw material name Dosage (parts by weight) Solvent - Cyclohexylsiloxane 35 copies Solvent - Propylene Glycol 10 copies Solvent-glycerol 5 copies Antioxidant - Ferulic Acid 0.4 copies Antioxidant - Tocopheryl Acetate 0.2 copies pH adjuster - citric acid 0.8 copies pH adjuster - sodium citrate 0.8 copies Preservative - Phenoxyethanol 0.4 copies Preservative - behenyltrimethylammonium chloride 0.1 copies

[0051] A method for preparing a precipitated vitamin C complex includes the following steps:

[0052] A1. Add sodium dihydrogen phosphate to deionized water at a mass ratio of 9:1 (sodium hydrogen phosphate: disodium hydrogen phosphate) and adjust the pH to 3.2 to form an acidic buffer solution. Slowly add 10 parts of L-ascorbic acid to the buffer solution, place it in an ice bath at 0°C, and stir with a magnetic stirrer at 250 rpm for 10 minutes until completely dissolved to obtain an acidic vitamin C solution.

[0053] A2. Add 8 parts of chitosan to a 1% v / v acetic acid solution and stir at 25°C for 30 minutes until completely dissolved to form a 1% w / v chitosan solution (pH=4.5). Keep the solution in an ice bath at 0°C and add acidic vitamin C solution dropwise at a rate of 1 mL / min, stirring continuously at 300 rpm during the addition. After the addition is complete, add 0.2 parts of crosslinking agent - 50% genipin propylene glycol solution and continue stirring for 20 minutes to form a microcapsule suspension.

[0054] A3. Feed the microcapsule suspension into a spray dryer, set the inlet air temperature to 180℃, the outlet air temperature to 80℃, and the feed rate to 5mL / min. After drying, collect the microcapsule powder (moisture content ≤3%).

[0055] A4. Add 1.5 parts magnesium aluminum silicate and 0.2 parts silica to 5 mL of propylene glycol, stir at 25°C for 20 minutes until completely dispersed to form a sedimentation aid coating solution; send the microcapsule dry powder into a fluidized bed coating machine, set the inlet air temperature to 60°C and the atomization pressure to 0.2 MPa, spray the coating solution onto the surface of the microcapsule dry powder at a rate of 2 mL / min, and continue fluidized drying for 10 minutes after spraying to obtain a sedimented vitamin C complex.

[0056] The method for preparing the upper layer solution includes the following steps:

[0057] Add 35 parts of cyclohexylsiloxane, 10 parts of propylene glycol, and 5 parts of glycerol to a mixing tank, heat to 40°C, and stir with a paddle stirrer at 150 rpm for 15 minutes until the system is transparent and homogeneous. Keep the temperature constant at 40°C, and add 0.4 parts of ferulic acid and 0.2 parts of tocopheryl acetate in sequence, stirring for 5 minutes until dissolved. Then add 0.8 parts of citric acid and 0.8 parts of sodium citrate, and stir for 5 minutes. Finally, add 0.4 parts of phenoxyethanol and 0.33 parts of 30% behenyltrimethylammonium chloride aqueous solution (0.1 parts after purification), and stir for 10 minutes to obtain the supernatant solution.

[0058] Packaging of a highly stable vitamin C composition: A 250mL brown glass bottle (light-proof packaging material: high borosilicate glass) is used. First, 100g of the upper layer solution is injected into the bottle; then 8g of the above-mentioned precipitated vitamin C complex is added; the air in the bottle is extracted by a vacuum pump (vacuum degree -0.09MPa), and at the same time, a mixed gas of 95%N2 + 5%CO2 (purity ≥99.99%) is injected. After purging 3 times, the bottle is immediately sealed with a butyl rubber stopper and an aluminum cap, and stored away from light.

[0059] Example 3

[0060] A highly stable vitamin C composition comprising a sedimenting vitamin C complex and a supernatant solution. The density of the sedimenting vitamin C complex is greater than the density of the supernatant solution.

[0061] The precipitated vitamin C complex comprises the following raw materials in parts by weight, as shown in Table 5.

[0062] Table 5

[0063] Raw material name Dosage (parts by weight) L-Ascorbic Acid 12 copies Chitosan 10 copies Crosslinking agent - 50% genipin propylene glycol solution 0.3 copies Settling aid - magnesium aluminum silicate (particle size ≤10μm) 2.5 portions Flocculant - Silica (Fused Silica) 0.5 copies

[0064] The upper layer solution comprises the following parts by weight of raw materials, as shown in Table 6.

[0065] Table 6

[0066] Raw material name Dosage (parts by weight) Solvent - Cyclohexylsiloxane 45 copies Solvent - Propylene Glycol 15 copies Solvent-glycerol 10 copies Antioxidant - Ferulic Acid 0.6 copies Antioxidant - Tocopheryl Acetate 0.4 copies pH adjuster - citric acid 1.2 portions pH adjuster - sodium citrate 1.2 portions Preservative - Phenoxyethanol 0.6 copies Preservative - behenyltrimethylammonium chloride 0.3 copies

[0067] A method for preparing a precipitated vitamin C complex includes the following steps:

[0068] A1. Add sodium dihydrogen phosphate to deionized water at a mass ratio of 9:1 (sodium hydrogen phosphate: disodium hydrogen phosphate) and adjust the pH to 3.2 to form an acidic buffer solution. Slowly add 12 parts of L-ascorbic acid to the buffer solution, place it in an ice bath at 0°C, and stir with a magnetic stirrer at 250 rpm for 10 minutes until completely dissolved to obtain an acidic vitamin C solution.

[0069] A2. Add 10 parts of chitosan to a 1% v / v acetic acid solution and stir at 25°C for 30 minutes until completely dissolved to form a 1% w / v chitosan solution (pH=4.5). Keep the solution in an ice bath at 0°C and add acidic vitamin C solution dropwise at a rate of 1 mL / min, stirring continuously at 300 rpm during the addition. After the addition is complete, add 0.3 parts of crosslinking agent - 50% genipin propylene glycol solution and continue stirring for 20 minutes to form a microcapsule suspension.

[0070] A3. Feed the microcapsule suspension into a spray dryer, set the inlet air temperature to 180℃, the outlet air temperature to 80℃, and the feed rate to 5mL / min. After drying, collect the microcapsule powder (moisture content ≤3%).

[0071] A4. Add 2.5 parts magnesium aluminum silicate and 0.5 parts silica to 5 mL of propylene glycol, stir at 25°C for 20 minutes until completely dispersed to form a sedimentation aid coating solution; send the microcapsule dry powder into a fluidized bed coating machine, set the inlet air temperature to 60°C and the atomization pressure to 0.2 MPa, spray the coating solution onto the surface of the microcapsule dry powder at a rate of 2 mL / min, and continue fluidized drying for 10 minutes after spraying to obtain a sedimented vitamin C complex.

[0072] The method for preparing the upper layer solution includes the following steps:

[0073] Add 45 parts of cyclohexylsiloxane, 15 parts of propylene glycol, and 10 parts of glycerol to a mixing tank, heat to 40°C, and stir with a paddle stirrer at 150 rpm for 15 minutes until the system is transparent and homogeneous. Keep the temperature constant at 40°C, and add 0.6 parts of ferulic acid and 0.4 parts of tocopheryl acetate in sequence, stirring for 5 minutes until dissolved. Then add 1.2 parts of citric acid and 1.2 parts of sodium citrate, stirring for 5 minutes. Finally, add 0.6 parts of phenoxyethanol and 1.0 part of 30% behenyltrimethylammonium chloride aqueous solution (0.3 parts after purification), and stir for 10 minutes to obtain the supernatant solution.

[0074] Packaging of a highly stable vitamin C composition: A 250mL brown glass bottle (light-proof packaging material: high borosilicate glass) is used. First, 100g of the upper layer solution is injected into the bottle; then 10g of the above-mentioned precipitated vitamin C complex is added; the air in the bottle is extracted by a vacuum pump (vacuum degree -0.09MPa), and at the same time, a mixed gas of 95%N2 + 5%CO2 (purity ≥99.99%) is injected. After purging 3 times, the bottle is immediately sealed with a butyl rubber stopper and an aluminum cap and stored away from light.

[0075] Comparative Example 1

[0076] The difference from Example 1 is that no settling aid (magnesium aluminum silicate and silicon dioxide) is added. That is, the settling vitamin C complex consists only of L-ascorbic acid, chitosan and cross-linking agent, without settling aid coating, and the microcapsule dry powder is directly added to the upper solution.

[0077] Comparative Example 2

[0078] The difference from Example 1 is that L-ascorbic acid is directly dissolved in the upper solution, without forming a sedimentation complex.

[0079] Comparative Example 3

[0080] The difference from Example 1 is that the cyclohexylsiloxane in the upper solution is replaced with an equal part by weight of mineral oil, and it does not have the function of hydrophobic and oxygen barrier.

[0081] test

[0082] 1. Density measurement test

[0083] Test Procedure: Measure the density of the precipitated vitamin C complex and the supernatant solution in Examples 1-3, Comparative Examples 1 and 3. During measurement, the samples were placed in a constant temperature environment of 25°C, and each sample was measured three times using a hydrometer, with the average value taken.

[0084] The density measurement test data are shown in Table 7.

[0085] Table 7

[0086] sample Density of sedimented vitamin C complex (g / cm³) Density of the upper layer solution (g / cm³) Example 1 1.05 0.92 Example 2 1.04 0.91 Example 3 1.06 0.93 Comparative Example 1 0.95 0.93 Comparative Example 3 1.05 0.88

[0087] 2. Storage stability test

[0088] Test Procedure: Take samples from Examples 1-3 and Comparative Examples 1-3, and aliquot them into three clean, dry 25mL brown glass bottles (15mL per bottle). Seal the bottle openings with butyl rubber stoppers (all samples are packaged in the same way). Place one group in a light-protected environment at 25℃±1℃ and 50%±5% humidity, place another group in a light-protected environment at 40℃±1℃ and 75%±5% humidity, and refrigerate the remaining group at 4℃ as an initial control. Take samples on days 0, 7, 28, and 60, and titrate with a standardized 0.05mol / L iodine standard solution (add 1% starch indicator until the blue color persists for 30 seconds) to determine the VC content. At the same time, observe the solution color (colorless / pale yellow / yellow) and transparency (transparent / slightly turbid / turbid) under natural light, and compare the VC retention rate and appearance changes of each group.

[0089] The data from the storage stability test are shown in Table 8.

[0090] Table 8

[0091]

[0092] As shown in Table 8, the vitamin C compositions of Examples 1-3 exhibited excellent stability under different storage conditions: after 60 days of storage at 25℃±1℃ / 50%±5%RH, the vitamin C retention rate remained at 90.5%-93.4%, the color remained pale yellow, and the transparency remained slightly turbid; under the harsh conditions of 40℃±1℃ / 75%±5%RH, the vitamin C retention rate was still 83.2%-87.6% after 60 days, with no obvious deterioration in appearance; under refrigeration at 4℃, the vitamin C retention rate was close to 99%, basically maintaining the initial colorless and transparent state. In contrast, the vitamin C retention rates of Comparative Example 1 (without flocculant), Comparative Example 2 (without chitosan microencapsulation), and Comparative Example 3 (cyclohexylsiloxane replaced with mineral oil) were significantly lower, at only 67.3%, 31.6%, and 59.8% respectively after 60 days at 25℃, and generally showed problems of darkening color (yellow to dark yellow) and turbidity. This indicates that the design of the sedimentation complex, the microencapsulation technology, and the combination of hydrophobic solvents in this invention are key to ensuring storage stability.

[0093] 3. Oxidation rate test

[0094] Test Procedure: Take samples from Examples 1-3 and Comparative Examples 1-3, and aliquot them into three clean, dry 25mL brown glass bottles (15mL per bottle). Seal the bottle openings with butyl rubber stoppers. During the test, pour out 10mL of transparent sample cell (unsealed, simulating exposure by opening the cap), and place it in a 25℃ environment at a distance of 30cm from a 5000lux sunlight simulator. Take 0.5mL samples at 0, 2, 8, and 24 hours, add 2,4-dinitrophenylhydrazine for derivatization, and determine the dehydroascorbic acid content. Take another 0.1mL sample, dilute it 10 times, and measure the absorbance (VC characteristic absorption peak) at a wavelength of 265nm. Calculate the oxidation rate (absorbance decrease / time) and compare the amount of oxidation products generated and the absorbance changes between the Examples and Comparative Examples.

[0095] The data from the oxidation rate test are shown in Table 9.

[0096] Table 9

[0097] sample 0-hour absorbance 2-hour absorbance 8-hour absorbance 24-hour absorbance Oxidation rate (absorbance / hour) Example 1 1.000 0.920 0.810 0.690 0.0129 Example 2 1.000 0.925 0.815 0.695 0.0127 Example 3 1.000 0.915 0.805 0.685 0.0131 Comparative Example 1 1.000 0.850 0.650 0.400 0.0250 Comparative Example 2 1.000 0.750 0.500 0.150 0.0354 Comparative Example 3 1.000 0.830 0.620 0.350 0.0271

[0098] As shown in Table 9, the oxidation rates of Examples 1-3 were low, all within the range of 0.0127-0.0131 absorbance / hour, and the absorbance remained at 0.685-0.695 after 24 hours, indicating that the oxidative degradation of vitamin C was slow. In contrast, the oxidation rate of Comparative Example 1 (without flocculant) reached 0.0250 absorbance / hour, Comparative Example 2 (without microencapsulation) had an oxidation rate as high as 0.0354 absorbance / hour, and Comparative Example 3 (mineral oil replacing cyclohexylsiloxane) had an oxidation rate of 0.0271 absorbance / hour, all of which were much higher than those of the Examples. This confirms that the present invention can significantly inhibit the oxidation rate of vitamin C through the synergistic effect of oxygen isolation by sedimentation, protection by microencapsulation, and oxygen isolation by hydrophobic solvent, thus solving the problem of easy oxidation when the traditional product is exposed after opening.

[0099] 4. Settlement behavior verification test

[0100] Test Procedure: Take samples from Examples 1-3 and Comparative Example 1, and aliquot them into three clean, dry 25mL brown glass bottles (15mL per bottle). Seal the bottle openings with butyl rubber stoppers. Pour out a 40mL stoppered graduated cylinder (multiple samples need to be combined to ensure consistent volume), and place it horizontally to avoid vibration. Observe and record the time for complete sedimentation of the complex (no suspended particles in the upper layer) after standing for 10 seconds, 30 seconds, and 24 hours. After 24 hours, take 10mL of the upper layer solution and measure the turbidity (NTU) using a turbidimeter. Then, take 0.1g of the bottom complex, add 10mL of water, and ultrasonically disperse it. Measure the particle size distribution (D10 / D50 / D90) using a laser particle size analyzer (test range 0.1-100μm) to verify the effect of the sedimentation aid on sedimentation rate and dispersibility.

[0101] The data from the settlement behavior verification test are shown in Table 10.

[0102] Table 10

[0103] sample Settling state after 10 seconds Settling state after 30 seconds Complete settling time (s) after 24 hours of standing. Turbidity of the upper layer solution (NTU) Particle size distribution of the complex (D10 / D50 / D90, μm) Example 1 Partial settling (a small amount of suspension) Completely settled (no suspension) 15 0.2 5.2 / 12.8 / 28.3 Example 2 Partial settling (a small amount of suspension) Completely settled (no suspension) 18 0.1 5.5 / 13.1 / 29.0 Example 3 Partial settling (a small amount of suspension) Completely settled (no suspension) 14 0.1 4.9 / 12.5 / 27.6 Comparative Example 1 Incompletely settled (clearly suspended) Partial settling (mostly suspended) 120 5.8 18.2 / 42.7 / 95.4

[0104] As shown in Table 10, the flocculant (magnesium aluminum silicate and silica) significantly optimizes the sedimentation behavior of the composite: the composites in Examples 1-3 can completely settle within 30 seconds, with a complete sedimentation time of only 14-18 seconds. The turbidity of the upper solution is as low as 0.1-0.2 NTU (high clarity), and the particle size distribution of the composite is uniform (D50 is 12.5-13.1 μm). In contrast, Comparative Example 1 (without flocculant) requires 120 seconds to completely settle, with a turbidity of 5.8 NTU in the upper solution (significantly turbid), and the particle size of the composite is significantly larger and unevenly distributed (D50 is 42.7 μm). This indicates that the flocculant can not only accelerate the sedimentation of the composite, but also ensure the clarity of the system and the uniformity of particle dispersion.

[0105] 5. Dispersion uniformity test

[0106] Test Procedure: Take samples from Example 1 and Comparative Examples 2-3, and aliquot them into three clean, dry 25mL brown glass bottles (15mL per bottle). Seal the bottle openings with butyl rubber stoppers. During the test, take one bottle of sample and shake it at a frequency of 2 times per second for 30 seconds (60 times in total). Immediately observe whether there are any visible particles. Let it stand for 10 minutes and observe whether it settles again. Take another 10mL of the shaken sample (combine multiple bottles to ensure the amount used) into a centrifuge tube, centrifuge at 3000rpm for 5 minutes, and take 1mL of each of the upper layer (1cm from the liquid surface), middle layer (middle position), and lower layer (1cm from the bottom of the tube). Determine the VC concentration using the iodometric method, calculate the concentration difference between the upper and lower layers (≤5% is considered uniform), and evaluate the dispersion effect.

[0107] The data from the dispersion uniformity test are shown in Table 11.

[0108] Table 11

[0109] sample Particles (≥50μm) are visible to the naked eye after shaking. Does it settle again after 10 minutes? VC concentration (mg / mL) after centrifugation Concentration difference between upper and lower layers (%) Uniformity evaluation Example 1 none no Top layer: 12.4 Middle layer: 12.3 Bottom layer: 12.5 1.6% uniform Comparative Example 2 Contains (a small amount of coarse particles) Yes (clearly stratified) Top layer: 11.8 Middle layer: 9.2 Bottom layer: 7.6 36.4% Uneven Comparative Example 3 There are (a small amount of particles). It is (slight stratification) Top layer: 12.1 Middle layer: 10.5 Bottom layer: 9.8 23.1% Uneven

[0110] As shown in Table 11, the composition of Example 1 exhibits good dispersion uniformity: no visible particles (≥50μm) are observed after shaking, no re-settling occurs after standing for 10 minutes, and the concentration difference between the upper and lower layers of VC after centrifugation is only 1.6%, meeting the uniformity requirements. In contrast, Comparative Example 2 (without microencapsulation) contains a small amount of coarse particles after shaking, and obvious re-settling occurs after standing for 10 minutes, with a concentration difference between the upper and lower layers reaching 36.4% after centrifugation. Comparative Example 3 (mineral oil replacing cyclohexylsiloxane) also shows visible particles and slight stratification, with a concentration difference of 23.1%, all failing to meet the uniformity requirements. This demonstrates that the microencapsulation process and sedimentation aid coating design of the present invention can ensure rapid and uniform dispersion of the complex after shaking, and good stability after dispersion.

[0111] In summary, this invention achieves multiple technical advantages through the synergistic design of a sedimentation-type vitamin C complex (L-ascorbic acid microencapsulation + sedimentation agent coating) and an upper hydrophobic aqueous solution (cyclohexylsiloxane as the core solvent): First, it significantly improves storage stability, reducing VC oxidation loss and appearance deterioration; second, it reduces the oxidation rate, alleviating activity loss during use after opening; and third, it ensures rapid sedimentation and uniform dispersion of the complex, balancing isolation and protection during storage with a smooth feel on the skin during use. This effectively solves the industry pain points of traditional vitamin C cosmetics, such as "frequent opening for oxidation, discoloration during storage, loss of activity during use, and uneven dispersion," providing a highly stable VC composition solution for whitening and anti-aging cosmetics.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A highly stable vitamin C composition, characterized in that, It consists of a sedimented vitamin C complex and an upper solution; The precipitating vitamin C complex comprises the following raw materials in parts by weight: 10-12 parts L-ascorbic acid, 8-10 parts chitosan, 0.2-0.3 parts crosslinking agent, and 1.5-2.5 parts flocculant; wherein the crosslinking agent is a 50% genipin propylene glycol solution; The upper layer solution is composed of the following raw materials in parts by weight: 50-70 parts solvent, 0.6-1.0 parts antioxidant, 1.6-2.4 parts pH adjuster and 0.5-0.9 parts preservative; The density of the precipitated vitamin C complex is greater than the density of the upper layer solution; The settling aid is a mixture of magnesium aluminum silicate and silicon dioxide; The mass ratio of magnesium aluminum silicate to silicon dioxide is 1.5-2.5:0.2-0.5; The method for preparing the precipitated vitamin C complex is as follows: A1. Dissolve L-ascorbic acid in an acidic buffer solution and stir in an ice bath at 0-5°C until completely dissolved to form an acidic vitamin C solution; the acidic buffer solution is a pH 3.2 buffer solution prepared by adding sodium dihydrogen phosphate and disodium hydrogen phosphate in deionized water at a mass ratio of 9:

1. A2. Dissolve chitosan in a 1% v / v acetic acid solution to form a chitosan solution; then add acidic vitamin C solution dropwise into the chitosan solution, and then add a cross-linking agent to form a microcapsule suspension; A3. The microcapsule suspension is spray-dried to obtain microcapsule dry powder; A4. Magnesium aluminum silicate and silicon dioxide are dissolved in propylene glycol to form a coating solution. The coating solution is then sprayed onto the surface of the microcapsule dry powder using a fluidized bed coating machine to obtain a sedimented vitamin C complex. The solvent is composed of cyclohexylsiloxane, propylene glycol and glycerol, wherein the mass ratio of cyclohexylsiloxane, propylene glycol and glycerol is 35-45:10-15:5-10. The antioxidant is composed of ferulic acid and tocopherol acetate, wherein the mass ratio of ferulic acid to tocopherol acetate is 0.4-0.6:0.2-0.4; The pH adjuster is composed of citric acid and sodium citrate, wherein the mass ratio of citric acid to sodium citrate is 0.8-1.2:0.8-1.2; The preservative is composed of phenoxyethanol and behenyltrimethylammonium chloride, wherein the mass ratio of phenoxyethanol to behenyltrimethylammonium chloride is 0.4-0.6:0.1-0.3; The vitamin C composition is packaged in light-proof packaging material; during packaging, the upper layer solution is injected first, and then the sedimenting vitamin C complex is added.

2. The application of the highly stable vitamin C composition as described in claim 1 in the preparation of whitening and anti-aging cosmetics, characterized in that, The cosmetic product is in the form of anhydrous essence.

3. The application of the highly stable vitamin C composition as described in claim 1 in the preparation of whitening and anti-aging cosmetics, characterized in that, The cosmetic product is in the form of anhydrous emulsion.

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