Skin care nanoemulsion containing anacardium occidentale l. oil and coffee cherry extract, preparation method and application thereof

Abstract

The application discloses a skin care nanoemulsion containing Plukenetia volubilis oil and coffee fruit peel extract, a preparation method and application thereof, and belongs to the technical field of cosmetic raw materials and nano preparations. The skin care nanoemulsion comprises the following components in percentage by mass: Plukenetia volubilis oil 2.0%-5.0%, coffee fruit peel extract liquid 8%-16.0%, lecithin 1.5%-2.5%, polyglycerol-6 oleate 1%-1.5%, glycerol 2.0%-4.0%, a pH regulator in an appropriate amount (so as to make the pH 5.2-5.8), and the balance being water. The preparation method of the nanoemulsion and the application thereof in the preparation of skin care products are also provided. The Plukenetia volubilis oil is compounded with the coffee fruit peel extract liquid, the lecithin and the polyglycerol-6 oleate are synergistically emulsified, and the nanoemulsion is prepared through a high-speed shearing and high-pressure homogenization process. The obtained nanoemulsion has small particle size, uniform distribution and excellent stability, has significant antioxidant, anti-inflammatory and soothing effects, and can be added to various skin care products as an effective raw material.

Description

Technical Field

[0001] This invention belongs to the field of cosmetic raw materials and nano-preparations technology, specifically relating to an oil-in-water skin care nanoemulsion containing Sacha inchi oil and coffee peel extract, as well as its preparation method and application in skin care products. Background Technology

[0002] With increasing consumer demand for gentle, safe, and naturally derived skincare ingredients, the application of plant oils, polyphenols, and polysaccharides in cosmetics and topical skincare preparations has garnered widespread attention. The skin barrier, primarily composed of the stratum corneum, reduces the penetration of external irritants while limiting the delivery of most active ingredients to the deeper layers of the skin. Therefore, improving the dispersion stability, antioxidant stability, and skin delivery efficiency of natural active substances without significantly compromising the safety of the skin barrier is a crucial issue in the development of natural functional skincare formulations. While traditional systems involving the direct addition of plant oils in lotions, creams, or other forms are simple, they often suffer from insufficient oxidative stability, uneven oil phase dispersion, greasy texture, and limited transdermal absorption efficiency for oily ingredients rich in unsaturated fatty acids.

[0003] Sacha indica ( Plukenetia volubilisSacha inchi (also known as Inca Inchi) has seed oil rich in unsaturated fatty acids such as alpha-linolenic acid, linoleic acid, and oleic acid, as well as accompanying active ingredients such as tocopherols and phytosterols. It has potential applications as a skin barrier lipid supplement, antioxidant, and soothing oil-based ingredient. Cosmetic patents related to Sacha inchi or plants of the genus *Plukenetia* have already disclosed its use in topical skin applications. For example, US20070264221A1 discloses cosmetic or pharmaceutical preparations containing extracts of plants of the genus *Plukenetia*, emphasizing the application of its protein extracts in anti-inflammatory, firming, and anti-aging effects; EP1807038A1 also relates to the use of extracts or proteins of plants of the genus *Plukenetia* in cosmetics; WO2014134834A1 discloses compositions containing *Inca Inchi* oil and sea buckthorn oil, which can be used in food and cosmetics; CN104825366A discloses a *Sapindus mukorossi* moisturizing cream and its preparation method, which uses *Sapindus mukorossi* oil, *Panax ginseng* stem and leaf extract, and a traditional cream oil phase to prepare the moisturizing cream. This technology focuses on moisturizing and improving rough skin, but lacks a systematic design for oil droplet nano-sizing, particle size distribution, PDI (particulate direct injection), skin delivery of active ingredients, or protection against polyunsaturated fatty acid oxidation. CN108815025A discloses a method for preparing a Sacha indica moisturizing emulsion, mainly using Sacha indica oil, Sacha indica powder, astringent extract, and a composite emulsifier. CN109276483A discloses a Sacha indica oil microemulsion and its preparation method, which can achieve a high content of Sacha indica oil in the microemulsion and improve system stability. However, this technology mainly focuses on increasing the content of Sacha indica oil and forming a stable microemulsion. Its formulation still relies on conventional surfactants and co-surfactants, and does not involve the multifunctional utilization of coffee fruit peel extract in terms of interface stability, anti-oxidation, preservative assistance, and skin delivery. It also does not establish a transdermal / intradermal retention verification scheme using endogenous indicators such as α-linolenic acid and chlorogenic acid as evaluation objects. The above technologies demonstrate that Sacha inchi oil already has a foundation for application in the fields of topical use or beauty and health care. However, these solutions are mostly focused on the moisturizing, skin-nourishing or ordinary emulsification and dispersion of Sacha inchi oil itself. There is insufficient research on its synergistic delivery with water-soluble natural penetration-enhancing components, and there are also few designs for nanoemulsion systems based on the overall concept of "oil phase activity stabilization - interface layer regulation - skin delivery enhancement - anti-inflammatory and antioxidant synergy".

[0004] Coffee pericarp is one of the main byproducts generated during the processing of fresh coffee cherries. It contains polyphenolic compounds, chlorogenic acid, caffeine, flavonoids, organic acids, pectin-like polysaccharides, and soluble dietary fiber, and has antioxidant, antibacterial, anti-inflammatory, and resource utilization value. In recent years, coffee pericarp has gradually transformed from a traditional agricultural byproduct into a raw material for functional foods, beverages, and cosmetics. CN108347957A discloses a method for preparing coffee fruit extract and powder, emphasizing that coffee fruit products are rich in antioxidants that can reduce oxidation and prevent oxidative damage, and can be used for nutritional and cosmetic purposes; CN112168880A discloses a method for extracting polyphenols from coffee pericarp, using ultrasonic-assisted microwave extraction to improve the extraction efficiency of coffee pericarp polyphenols; CN110419658A discloses a coffee pericarp nutrient solution and its preparation method, mainly designed from the perspectives of coffee pericarp resource utilization, low-temperature extraction, and nutrient solution production. Other public reports indicate that phenolic components such as chlorogenic acid, caffeic acid, and protocatechuic acid can be obtained from coffee fruit peel through specific extraction techniques, further demonstrating the development value of coffee fruit peel as a source of polyphenols.

[0005] However, most existing patents related to coffee peel focus on the "extraction method," "nutrient solution," "powder," or "antioxidant raw material" itself, failing to fully address its application in oil-based skincare systems. Coffee peel extracts are typically water-soluble or hydrophilic components, containing polysaccharides and polyphenols with numerous hydroxyl, carboxyl, and aromatic groups. Theoretically, they can participate in oil-water interface stabilization, free radical scavenging, metal ion complexation, and regulation of the stratum corneum microenvironment. However, if directly added to ordinary emulsions or aqueous solutions, they are easily affected by pH, ionic strength, system viscosity, and oil-water phase compatibility, leading to insufficient activity utilization. Especially in systems containing plant oils with high levels of unsaturated fatty acids, the interfacial interaction between aqueous polyphenols / polysaccharides and oil-phase lipids cannot be achieved simply by mixing; a stable nanoscale dispersion structure still needs to be established through formulation ratios, emulsifier types, homogenization pressure, and particle size distribution control.

[0006] Furthermore, nanoemulsions are submicron-scale dispersion systems composed of an oil phase, an aqueous phase, emulsifiers, and auxiliary emulsifiers. They are characterized by small particle size, large specific surface area, uniform translucent or milky-white appearance, and good kinetic stability. For topical skin preparations, nanoemulsions can improve the dispersibility of oily components in aqueous systems, increase the contact area with the skin surface, and enhance the distribution and local retention of active substances in the stratum corneum through small-diameter oil droplets, surfactants, and hydration. Therefore, preparing nanoemulsions from highly unsaturated fatty acid plant oils is an important direction for improving their topical stability and skin bioavailability. However, existing patents related to Sacha inchi oil are mostly traditional moisturizing creams, emulsions, or microemulsion systems, while patents related to coffee peel are mostly extracts, nutrient solutions, or antioxidant raw materials. There is a lack of specific nanoemulsion combination schemes that use Sacha inchi oil as the oil phase and coffee peel extract as the functional aqueous phase.

[0007] In summary, existing technologies have at least the following shortcomings: First, existing sacha inchi oil skincare formulations mostly emphasize moisturizing, hydration, or the stability of ordinary microemulsions, with insufficient attention to the oxidative protection and local skin delivery of polyunsaturated fatty acids in sacha inchi oil in topical systems; Second, existing coffee peel technologies mostly focus on extraction processes, beverages, or antioxidant raw materials, with insufficient utilization of the complex functions of its polysaccharides and polyphenols as interfacial stabilizers and skin delivery aids; Third, existing emulsion technologies often rely on high doses of conventional surfactants or chemical penetration enhancers, lacking technical solutions that utilize natural extracts to participate in interfacial regulation while also ensuring gentleness; Fourth, existing technologies rarely combine antioxidant, particle size stability, and local skin retention of endogenous active indicators for systematic formulation screening.

[0008] In summary, although existing technologies disclose the preparation and application of Sacha inchi oil and coffee peel extract, there is no technical solution that can construct the two in a specific ratio into a water-in-oil nanoemulsion for skin care, and obtain good physical and oxidative stability as well as the local skin retention effect of active ingredients. Summary of the Invention

[0009] To overcome the shortcomings of existing sacha inchi oil skincare formulations, such as insufficient oil-phase dispersibility and oxidative stability, limited local skin delivery efficiency, and the difficulty in forming a stable complex system between coffee peel extract and oil-phase active ingredients, this invention provides a skincare nanoemulsion containing sacha inchi oil and coffee peel extract, its preparation method, and its application. This invention uses sacha inchi oil as the core active oil-phase component and coffee peel extract as the functional aqueous phase component. An emulsification interface is constructed using lecithin and polyglycerol-6 oleate. After high-speed shearing and high-pressure homogenization, a skincare nanoemulsion with an average particle size of 90–160 nm and a PDI ≤0.25 is obtained. The resulting nanoemulsion can improve the oxidative stability of polyunsaturated fatty acids in sacha inchi oil, promote the local retention of oil-phase and aqueous-phase active ingredients in the skin, and also possesses antioxidant, anti-inflammatory, and soothing effects.

[0010] To achieve the above objectives, the present invention provides the following technical solution: First, the present invention provides a skin care nanoemulsion containing sacha inchi oil and coffee fruit peel extract, which, by mass percentage, consists of the following components: sacha inchi oil 2.0%–5.0%, coffee fruit peel extract liquid 8%–16.0%, lecithin 1.5%–2.5%, polyglycerol-6 oleate 1%–1.5%, glycerin 2.0%–4.0%, a suitable amount of pH adjuster (to adjust the pH of the skin care nanoemulsion to 5.2–5.8), and the balance being water.

[0011] The coffee fruit peel extract contains 3.0%–6.0% soluble solids, 1.0–2.5 mg / mL total polyphenols (gallic acid equivalent), and 2.0–8.0 mg / mL total polysaccharides (glucose equivalent). These specifications ensure that the coffee fruit peel extract can effectively contribute to interfacial stability and provide functional components in the nanoemulsion system.

[0012] The skin-care nanoemulsion has a pH of 5.2–5.8, an average particle size of 90–160 nm, and a PDI ≤ 0.25. Controlling the pH of the finished product within the weakly acidic range of 5.2–5.8, which is close to the pH of human skin, helps maintain the skin barrier function and reduces irritation. Controlling the average particle size at the nanoscale improves the local retention of the active oil-phase ingredients in the skin.

[0013] In some preferred embodiments, the sacha inchi oil contains 42.0%–52.0% α-linolenic acid, 30.0%–40.0% linoleic acid, and 6.0%–12.0% oleic acid, and has a peroxide value ≤ 10 meq O2 / kg. Limiting the fatty acid composition and peroxide value helps ensure the quality and antioxidant potential of the active components in the oil phase.

[0014] In some preferred embodiments, the coffee pericarp extract is obtained by water extraction, filtration, and vacuum concentration (to 1 / 4-1 / 5 of the original volume) of coffee pericarp, with a pH of 3.80-4.60 and a chlorogenic acid content of 0.20-0.80 mg / mL. The chlorogenic acid in the coffee pericarp extract, as one of the aqueous phase antioxidant active components, together with the polyunsaturated fatty acids in sacha inchi oil, constitutes an oil-water biphase antioxidant system. More preferably, the mass-to-volume ratio of coffee pericarp to water is 1:5-15, the extraction temperature is 50-60℃, and the extraction is performed 1-2 times. Furthermore, to improve the polysaccharide dissolution rate, 0.05%-0.15% pectinase or cellulase can be added during extraction, and enzymatic hydrolysis is performed at pH 5.0-5.5 and 45-50℃ for 30-60 min, followed by inactivation at 80℃ for 10 min, and then filtration and concentration.

[0015] In some preferred embodiments, the lecithin is soybean lecithin, and the pH adjuster is a citric acid-sodium citrate buffer system. Lecithin, in combination with polyglycerol-6 oleate, forms an emulsifying interface and interacts with the polysaccharides and polyphenols in the coffee fruit peel extract, resulting in a nanoemulsion system with smaller particle size and lower PDI at lower emulsifier dosages. The citric acid-sodium citrate buffer system not only regulates and maintains the pH of the finished product, but citric acid itself also has a mild metal ion chelating effect, which is beneficial for inhibiting the oxidation of polyunsaturated fatty acids.

[0016] In a further preferred embodiment, the skin-care nanoemulsion comprises, by weight percentage: 3.5% Sacha involucrata oil, 12.0% coffee fruit peel extract, 2.0% lecithin, 1.0% polyglycerol-6 oleate, 4.0% glycerin, 0.05%–0.20% citric acid-sodium citrate buffer system (to adjust the pH of the skin-care nanoemulsion to 5.2–5.8), with the balance being water. This preferred formulation can form a skin-care nanoemulsion with an average particle size of approximately 100 nm, a PDI not exceeding 0.25, and good physical and oxidative stability.

[0017] Secondly, the present invention also provides a method for preparing the skin care nanoemulsion, comprising the following steps: (1) Mix sacha inchi oil and lecithin at 45-65°C to form an oil phase; (2) Mix coffee fruit peel extract, polyglycerol-6 oleate, glycerol, pH adjuster and water, and adjust the pH to 5.2-5.8 to form an aqueous phase; (3) The oil phase is slowly added to the aqueous phase and sheared at high speed for 3 to 8 minutes at 8000 to 12000 rpm to obtain a crude emulsion; (4) The crude milk is homogenized under high pressure at 80-120 MPa for 3-5 times, cooled to room temperature, pH adjusted to 5.2-5.8 and defoamed to obtain the final product.

[0018] Preferably, the high-speed shearing condition is 10,000 rpm for 6 min, and the high-pressure homogenization condition is 100 MPa for 3 cycles. By controlling the oil phase ratio, emulsifier ratio, amount of coffee fruit peel extract, and homogenization parameters, a skin-care nanoemulsion with an average particle size of approximately 100 nm, a PDI of no more than 0.25, and good physical stability can be obtained.

[0019] Furthermore, the present invention also provides a skin care product comprising the above-mentioned skin care nanoemulsion and cosmetically acceptable excipients, wherein the skin care nanoemulsion comprises 0.5% to 30% by mass in the skin care product.

[0020] Preferably, the skin care product is an essence water, serum, lotion, or cream.

[0021] Finally, the present invention also provides the application of the skin care nanoemulsion in the preparation of skin care products with antioxidant, anti-inflammatory and / or soothing effects.

[0022] Compared with the prior art, the present invention has the following beneficial effects: Synergistic effect and enhanced stability: This invention uses Sacha inchi oil as the oil phase and coffee pericarp extract with specific ranges of soluble solids, total polyphenols, and total polysaccharides as the functional aqueous phase, combined with lecithin and polyglycerol-6 oleate to form a stable nanoemulsion. The polyphenols and polysaccharides in the coffee pericarp extract not only provide antioxidant activity but also participate in interface construction, improving the physical and oxidative stability of the emulsion.

[0023] Small particle size and uniform distribution: The nanoemulsions obtained by combining high-speed shearing and high-pressure homogenization processes have an average particle size of 90-160 nm, PDI≤0.25, and a uniform appearance of semi-transparent or milky white, exhibiting excellent kinetic stability.

[0024] Excellent performance and safe and gentle: The nanoemulsion of this invention has significant antioxidant, anti-inflammatory and soothing effects, and can promote the local retention of active ingredients on the skin, making it especially suitable for sensitive skin and consumers who seek natural and functional skin care products.

[0025] By using specific specifications for coffee fruit peel extract (soluble solids, total polyphenols, and total polysaccharide content), the consistency and reproducibility of efficacy of different batches of raw materials in the nanoemulsion system are ensured.

[0026] The emulsification system combining lecithin and polyglycerol-6 oleate has high natural source properties and good mildness, achieving stable nanoemulsions at low dosages. The citric acid-sodium citrate buffer system provides mild antioxidant assistance while adjusting and maintaining the pH of the finished product.

[0027] The preparation method employs high-speed shearing combined with high-pressure homogenization, with clearly defined and scalable process parameters. The finished product has a pH controlled within a weakly acidic range of 5.2–5.8, making it suitable for direct or diluted application in skincare products. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to embodiments, but this does not limit the present invention in any way. Any modifications or improvements made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0029] The processes, conditions, reagents, and experimental methods used in implementing this invention, except as specifically mentioned below, are all common knowledge and general knowledge in the field, and this invention does not have any particular limitations. Experimental methods in the embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer.

[0030] Unless otherwise stated, all technical terms and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. However, in the event of any conflict, the specification containing the definitions shall prevail.

[0031] The following is some information about the source and specifications of the raw materials used in the examples: Coffee husks: Dried coffee husks obtained from processing fresh Yunnan small-bean coffee cherries, crushed and passed through a 40-mesh sieve for later use; the raw material is brownish-brown in the form of flakes or fragments, free from mold and obvious odor, with a moisture content of ≤12.0%, and should be stored away from light and in a dry place before use.

[0032] Sacha inchi oil: Commercially available cosmetic or food grade cold-pressed sacha inchi oil; α-linolenic acid content 42.0%~52.0%, linoleic acid content 30.0%~40.0%, oleic acid content 6.0%~12.0%, peroxide value ≤10 meq O2 / kg.

[0033] Lecithin: Commercially available cosmetic-grade soybean lecithin, which is a yellow to brownish-yellow viscous liquid or powder. Phosphatidylcholine and other phospholipid components meet the supplier's quality standards.

[0034] Polyglycerol-6 oleate: Commercially available cosmetic-grade polyglycerol-6 oleate is used as an auxiliary emulsifier. Its acid value, saponification value, heavy metals, and microbial limits meet the quality standards of cosmetic raw material suppliers.

[0035] Glycerin: Commercially available cosmetic grade glycerin, content ≥99.0%; citric acid and sodium citrate are analytical grade or cosmetic grade, and water is purified water.

[0036] Unless otherwise specified, the testing items involved in the following examples and comparative examples were all performed in accordance with the methods or reference standards described below.

[0037] (1) Average particle size and polydispersity index (PDI): Determined by dynamic light scattering (DLS). The instrument was a nanoparticle size and zeta potential analyzer (such as Malvern Zetasizer NanoZS90 or an instrument of equivalent precision). An appropriate amount of nanoemulsion sample was taken, diluted with purified water to an appropriate concentration (to avoid multiple scattering), transferred to a cuvette, and equilibrated at 25℃±0.1℃ for 120 s before measurement. Each sample was measured in triplicate, and 11 sets of data were collected each time. The intensity-average particle size (Z-Average) and the mean PDI were taken. Reference standard: GB / T 29022-2012 "Particle size analysis by dynamic light scattering (DLS)".

[0038] The particle size change rate is calculated using the following formula: Particle size change rate (%) = (average particle size after storage - average particle size before storage) / average particle size before storage × 100%.

[0039] (2) Centrifugal stability: Place approximately 10 mL of the nanoemulsion sample in a centrifuge tube and centrifuge at 4000 rpm for 30 min (room temperature, approximately 25℃). After centrifugation, observe whether the sample exhibits stratification, flocculation, precipitation, or oil droplet floating. If the appearance is uniform and shows no significant changes after centrifugation, the centrifugal stability is deemed acceptable. If necessary, the centrifugation speed can be increased to 8000 rpm or the centrifugation time extended to 60 min for accelerated evaluation.

[0040] (3) Viscosity: Measured using a rotational viscometer (such as a Brookfield DV2T or an instrument of equivalent precision). Select a suitable rotor model and rotation speed based on the estimated viscosity range of the sample. The test temperature is 25℃±0.5℃, and the sample volume should not be less than the minimum volume required by the rotor. Immerse the rotor in the sample, and record the viscosity value (mPa·s) after the reading stabilizes. Each sample is measured in triplicate, and the average value is taken. Reference standard: GB / T 22235-2008 "Determination of Viscosity of Liquids".

[0041] (4) Zeta Potential: Measured using electrophoretic light scattering (ELS). The instrument used was a nanoparticle size and zeta potential analyzer (such as the Malvern Zetasizer NanoZS90 or an instrument of equivalent precision). An appropriate amount of nanoemulsion sample was diluted with purified water to a suitable concentration and transferred to a capillary electrophoresis pool. The electrophoretic mobility was measured at 25℃±0.1℃, and the zeta potential was calculated using the Henry equation. Each sample was measured in triplicate, and the average value was taken. Reference standard: GB / T 32668-2016 / ISO 13099-1:2012.

[0042] (5) Peroxide value (POV) and peroxide value growth rate: The peroxide value was determined according to the titration method in GB 5009.227-2016 "National Food Safety Standard: Determination of Peroxide Value in Food". Take an appropriate amount of nanoemulsion sample, add a chloroform-glacial acetic acid mixed solution to fully dissolve the oil phase, add saturated potassium iodide solution, react in the dark, and then titrate to the endpoint with sodium thiosulfate standard solution. A blank test was performed simultaneously. The peroxide value was calculated using the following formula: POV(meq O2 / kg) = [(V1- V0) × c × 1000] / m In the formula: V1 is the volume of sodium thiosulfate standard solution consumed by the sample (mL); V0 is the volume of sodium thiosulfate standard solution consumed by the blank (mL); c is the concentration of sodium thiosulfate standard solution (mol / L); m is the sample mass (g).

[0043] The peroxide value growth rate is calculated using the following formula: Peroxide value growth rate (%) = (Post-storage POV - Pre-storage POV) / Pre-storage POV × 100%. The lower the peroxide value growth rate, the better the oxidative stability of the oil phase component in the nanoemulsion system.

[0044] (6) pH: Measured using a calibrated pH meter (accuracy 0.01). Two-point calibration was performed using standard buffer solutions (pH 4.00 and pH 6.86) before testing. An appropriate amount of nanoemulsion sample was taken and directly inserted into the electrode at 25℃±0.5℃. The reading was recorded after stabilization. Each sample was measured in triplicate, and the average value was taken. Reference standard: General Chapter 0631, pH determination method, Part IV of the Pharmacopoeia of the People's Republic of China.

[0045] (7) Soluble solids: Determined using a handheld refractometer or Abbe refractometer. Place 1-2 drops of coffee pericarp extract onto the refractometer prism and read the soluble solids content (%Brix) at 25℃±0.5℃. Zero the instrument with purified water before use. Perform three parallel determinations for each sample and take the average value. Reference standard: Determination of soluble solids in GB / T 12143-2008 "General Analytical Methods for Beverages".

[0046] (8) Total polyphenol content: determined by the Folin-Ciocalteu colorimetric method, using gallic acid as the standard. After diluting an appropriate amount of sample, Folin-Ciocalteu reagent and 7.5% sodium carbonate solution were added sequentially. The mixture was reacted at 45℃ for 30 min, and the absorbance was measured at 765 nm. A standard curve was plotted using a series of gallic acid concentrations. The total polyphenol content in the sample was calculated from the standard curve equation and expressed as gallic acid equivalents (mg GAE / mL).

[0047] (9) Total polysaccharide content: determined by the phenol-sulfuric acid method, using glucose as the standard. A suitable amount of sample was diluted, and 5% phenol solution and concentrated sulfuric acid were added. After shaking well, the mixture was reacted in a boiling water bath for 15 min. After cooling to room temperature, the absorbance was measured at a wavelength of 490 nm. A standard curve was plotted using a series of glucose concentrations, and the total polysaccharide content in the sample was calculated from the standard curve equation, expressed as glucose equivalents (mg GE / mL).

[0048] (10) Chlorogenic acid content: determined by high performance liquid chromatography (HPLC), with chlorogenic acid as the reference standard. Chromatographic conditions: C18 column (4.6 mm × 250 mm, 5 μm), mobile phase: acetonitrile-0.1% phosphoric acid solution gradient elution, detection wavelength: 327 nm, flow rate: 1.0 mL / min, column temperature: 30℃, injection volume: 10 μL. Quantification was performed using the external standard method with chlorogenic acid as the reference standard, and the result was expressed as chlorogenic acid (mg / mL). Reference standard: Pharmacopoeia of the People's Republic of China, Part IV, General Chapter 0512, High Performance Liquid Chromatography.

[0049] (11) Fatty acid composition of Sacha inchi oil (α-linolenic acid, linoleic acid, and oleic acid content): determined by gas chromatography, analyzed in the form of fatty acid methyl esters (FAME). After methylation, the Sacha inchi oil sample was injected into the gas chromatograph using a flame ionization detector (FID) and a capillary column (e.g., SP-2560, 100 m × 0.25 mm × 0.20 μm). The relative content of each fatty acid methyl ester was calculated using the area normalization method. Reference standard: GB 5009.168-2016 "National Food Safety Standard - Determination of Fatty Acids in Food".

[0050] (12) In the above determinations of total polyphenols, total polysaccharides, chlorogenic acid components, and fatty acid composition, reagent blanks and sample blanks were set to eliminate the influence of the color of the coffee fruit peel extract, the turbidity of the nanoemulsion, and the solvent background on the absorbance or chromatographic response. The correlation coefficient R² of the standard curve should not be less than 0.999. Each sample was measured in triplicate, and the results were expressed as mean ± standard deviation. When determining oil phase indicators in nanoemulsion samples, the target components were first extracted and demulsified using a suitable solvent such as methanol, isopropanol, or n-hexane, and then injected for determination after centrifugation or filtration.

[0051] Example 1: Preparation of Coffee Pericarp Extract A method for preparing a coffee fruit peel extract includes the following steps: (1) Take coffee fruit skins, crush them and pass them through a 40-mesh sieve; (2) Add purified water at a material-to-liquid ratio of 1:15, extract at 55℃ for 2 h, filter, and collect the filtrate; (3) Add purified water to the filter residue at a material-to-liquid ratio of 1:10, extract at 55℃ for 1 h, and combine the two filtrates; (4) The combined filtrate is concentrated under reduced pressure at a temperature below 45°C to 1 / 4 to 1 / 5 of its original volume to obtain coffee fruit peel extract.

[0052] The obtained coffee fruit peel extract was a brownish-yellow transparent liquid with a pH of 4.12 and a soluble solids content of 4.20%. The total polyphenol content, calculated as gallic acid, was 1.62 mg / mL; the chlorogenic acid content, calculated as chlorogenic acid, was 0.42 mg / mL; and the total polysaccharide content, calculated as glucose, was 3.28 mg / mL.

[0053] Example 2: Pectinase-assisted preparation of coffee pericarp extract A method for preparing a coffee fruit peel extract includes the following steps: (1) Take dried coffee husks, crush them and pass them through a 40-mesh sieve to obtain coarse coffee husk powder; (2) Add purified water to the coffee fruit powder at a ratio of 1:15 (g / mL), adjust the pH to 5.2 with citric acid, add pectinase (enzyme activity ≥500 U / g, the amount added is 0.08% of the raw material mass), and stir at 48℃ for 45 minutes for enzymatic hydrolysis. (3) After the enzymatic hydrolysis is completed, heat to 80℃ and keep warm for 10 minutes to inactivate the enzyme, filter, and collect the first filtrate; (4) Add purified water to the filter residue at a material-to-liquid ratio of 1:10 (g / mL), stir and extract at 55℃ for 1 hour, filter, and collect the second filtrate; (5) Combine the first and second filtrates and concentrate them under reduced pressure at below 45°C to 1 / 4 of the original volume to obtain coffee fruit peel extract.

[0054] The obtained coffee fruit peel extract was a light brownish-yellow slightly turbid liquid with a pH of 4.60 and a soluble solids content of 5.10%. The total polyphenol content, calculated as gallic acid, was 1.83 mg / mL; the chlorogenic acid content, calculated as chlorogenic acid, was 0.46 mg / mL; and the total polysaccharide content, calculated as glucose, was 5.42 mg / mL.

[0055] Example 3: Cellulase-assisted preparation of coffee pericarp extract A method for preparing a coffee fruit peel extract includes the following steps: (1) Take dried coffee husks, crush them and pass them through a 40-mesh sieve to obtain coarse coffee husk powder; (2) Add purified water to the coffee fruit powder at a ratio of 1:15 (g / mL), adjust the pH to 5.0 with citric acid, add cellulase (enzyme activity ≥10000 U / g, the amount added is 0.10% of the raw material mass), and stir at 45℃ for 60 minutes for enzymatic hydrolysis. (3) After the enzymatic hydrolysis is completed, heat to 80℃ and keep warm for 10 minutes to inactivate the enzyme, filter, and collect the first filtrate; (4) Add purified water to the filter residue at a material-to-liquid ratio of 1:10 (g / mL), stir and extract at 55℃ for 1 hour, filter, and collect the second filtrate; (5) Combine the first and second filtrates and concentrate them under reduced pressure at below 45°C to 1 / 4 of the original volume to obtain coffee fruit peel extract.

[0056] The obtained coffee fruit peel extract was a light brownish-yellow slightly turbid liquid with a pH of 3.80 and a soluble solids content of 5.35%. The total polyphenol content, calculated as gallic acid, was 1.76 mg / mL; the chlorogenic acid content, calculated as chlorogenic acid, was 0.44 mg / mL; and the total polysaccharide content, calculated as glucose, was 5.96 mg / mL.

[0057] Example 4: Preparation of a skin care nanoemulsion containing Sacha inchi oil and coffee pericarp extract The nanoemulsion formulations are shown in Table 1, and the coffee fruit peel extract is the sample prepared in Example 1.

[0058] Table 1 Nanoemulsion Formulation

[0059] The preparation method is as follows: Sacha inchi oil and lecithin are mixed, heated to 60℃, and stirred for 10 min to obtain the oil phase. Separately, coffee peel extract, polyglycerol-6 oleate, glycerol, citrate-sodium citrate buffer, and a portion of purified water are mixed, stirred evenly, and the pH is adjusted to 5.2–5.8 to obtain the aqueous phase. The oil phase is slowly added to the aqueous phase, and the mixture is subjected to high-speed shearing at 10,000 rpm for 6 min to obtain the crude emulsion. The crude emulsion is then homogenized three times under high pressure at 100 MPa, cooled to room temperature, and the pH is checked and corrected to 5.2–5.8 if necessary. After defoaming, the Sacha inchi oil-coffee peel extract nanoemulsion is obtained.

[0060] The obtained nanoemulsion was a uniform milky white to translucent liquid with an average particle size of 99.8 nm, a PDI of 0.20, a zeta potential of -30.1 mV, and a pH of 5.62. After centrifugation at 4000 rpm for 30 min, no stratification, flocculation, or obvious oil droplet floating was observed.

[0061] Example 5: Single-factor screening of the dosage of Chinese vine fruit oil in skin care nanoemulsions Referring to Example 4, while keeping the coffee fruit peel extract (12.00%), lecithin (2.00%), polyglycerol-6 oleate (1.00%), glycerol (4.00%), homogenization pressure (100 MPa), and homogenization cycles (3 times) constant, only the amount of Sacha inchi oil was varied to investigate the effect of oil phase content on nanoemulsion particle size, PDI, stability, and skin delivery performance. The results are shown in Table 2.

[0062] Table 2 Screening results for Sacha Inchi oil dosage

[0063] As shown in Table 2, when the amount of Sacha indica oil is below 2.00%, although the particle size is small, the loading of active substances in the oil phase is insufficient. When the amount of Sacha indica oil is above 5.00%, the particle size and PDI increase significantly, and the centrifugal stability decreases. Considering particle size, stability, and intradermal retention of α-linolenic acid, the optimal amount of Sacha indica oil under the conditions of this experiment is 2.00%–5.00%. Among them, the particle size, PDI, and intradermal retention in the range of 3.00%–4.00% show better overall performance. Therefore, 3.50% was selected as the intermediate level for further investigation in the subsequent three-factor, three-level representative combination formulation optimization experiment.

[0064] Example 6: Single-factor screening of the dosage of coffee fruit peel extract in skin care nanoemulsions Referring to Example 4, while maintaining the same concentrations of Sacha inchi oil (3.00%), lecithin (2.00%), polyglycerol-6 oleate (1.00%), glycerol (4.00%), homogenization pressure (100 MPa), and homogenization cycles (3 times), only the amount of coffee pericarp extract was varied to investigate its effects on emulsion particle size, PDI, chlorogenic acid retention within the pericarp, and its auxiliary effect in inhibiting microorganisms. The coffee pericarp extract was the sample prepared in Example 1. The results are shown in Table 3.

[0065] Table 3. Screening results of coffee fruit peel extract dosage

[0066] As shown in Table 3, when the amount of coffee fruit peel extract increased from 4.00% to 12.00%, the retention of chlorogenic acid in the peel significantly increased, while the particle size and PDI did not increase significantly. When the amount continued to increase to above 20.00%, the viscosity and ionic strength of the system increased, the particle size and PDI increased, and the emulsion stability decreased. Taking all factors into consideration, the preferred amount of coffee fruit peel extract is 8.00%–16.00%, and more preferably 12.00%.

[0067] Example 7: Single-factor screening of the dosage of phospholipid emulsifiers in skin care nanoemulsions Referring to Example 4, while keeping the following conditions constant: 3.00% Sacha inchi oil, 12.00% coffee pericarp extract, 1.00% polyglycerol-6 oleate, 4.00% glycerol, homogenization pressure 100 MPa, and homogenization times 3, only the amount of lecithin was changed. The results are shown in Table 4.

[0068] Table 4. Results of Lecithin Dosage Screening

[0069] As shown in Table 4, when the lecithin content is below 1.50%, the interfacial film formation is insufficient, the particle size is large, and the stability decreases; when the lecithin content is above 2.50%, the particle size reduction is not significant, and it may increase the stickiness of the system. Therefore, considering both emulsification efficiency and skin feel, the preferred lecithin content is 1.50%–2.50%, more preferably 2.00%.

[0070] Example 8 Screening of Auxiliary Emulsifier Types and Dosage Referring to Example 4, under the conditions of keeping the following constants: 3.00% Sacha inchi oil, 12.00% coffee pericarp extract, 2.00% lecithin, 4.00% glycerol, homogenization pressure 100 MPa, and homogenization times 3, different auxiliary emulsifiers and their dosages were investigated. The results are shown in Table 5.

[0071] Table 5 Screening results of auxiliary emulsifiers

[0072] As shown in Table 5, polyglycerol-6 oleate, when combined with lecithin, can form a nanoemulsion system with small particle size, low PDI, and good appearance. Considering mildness, natural source properties, emulsification efficiency, and skin feel, polyglycerol-6 oleate is preferred, and its dosage is preferably 1% to 1.5%, more preferably 1.00%.

[0073] Example 9 Effect of Glycerin Dosage and Ionic Strength on the Stability of Nanoemulsions The purpose of this embodiment is to investigate the effects of aqueous humectant and ionic strength on droplet size, PDI, viscosity, and thermal storage stability. The experiment was conducted with reference to Example 4, maintaining the following parameters: 3.00% Sacha inchi oil, 12.00% coffee pericarp extract, 2.00% lecithin, 1.00% polyglycerol-6 oleate, homogenization pressure of 100 MPa, and three homogenization cycles. Only the amount of glycerol was varied, or a small amount of sodium chloride was added. The preparation method was the same as in Example 4. The obtained samples were evaluated for particle size, PDI, viscosity, and particle size growth rate after 7 days of storage at 45°C. The results are shown in Table 6. Table 6. Effects of different glycerol dosages and ionic strengths on the stability of nanoemulsions.

[0074] The results showed that when the glycerol content was 2.0%–4.0%, the system particle size and PDI remained low, and the particle size increase rate after short-term heat storage at 45℃ was small. Excessive glycerol content increased the system viscosity and raised the PDI. The addition of 0.2% sodium chloride significantly increased the particle size, suggesting that the interface layer between polyphenols, polysaccharides, and phospholipids in the coffee fruit peel extract is sensitive to ionic strength. Therefore, this invention preferably uses a low-salt system, and controls the glycerol content to 2.0%–4.0%, more preferably 4.0%.

[0075] Example 10: Screening and Validation of Preparation Process Parameters While keeping the formulation of Example 4 unchanged, the effects of high-pressure homogenization pressure and homogenization times on nanoemulsion particle size, PDI, and storage stability were investigated. The results are shown in Table 7.

[0076] Table 7 Screening Results of High-Pressure Homogenization Processes

[0077] As shown in Table 7, when the homogenization pressure is below 80 MPa, the particle size and PDI are relatively high. When the homogenization pressure is 100 MPa and the homogenization is performed 3 times, nanoemulsions with a particle size of about 100 nm and good stability can be obtained. Further increasing the pressure or the number of homogenizations has limited effect on improving the particle size, but increases energy consumption. Therefore, the preferred homogenization pressure is 80-100 MPa and the number of homogenizations is 3-4 times, more preferably 100 MPa for 3 homogenizations.

[0078] Furthermore, based on the formulation of Example 4, representative boundary verification was performed on the oil phase mixing temperature and high-speed shearing conditions. The low boundary conditions were: oil phase mixing temperature 45℃, shearing at 8000 rpm for 3 min, and high-pressure homogenization three times at 80 MPa; the medium boundary conditions were: oil phase mixing temperature 60℃, shearing at 10000 rpm for 6 min, and high-pressure homogenization three times at 100 MPa; the high boundary conditions were: oil phase mixing temperature 65℃, shearing at 12000 rpm for 8 min, and high-pressure homogenization five times at 120 MPa. The results showed that under the above representative boundary and medium boundary conditions, water-in-oil nanoemulsions with uniform appearance and no obvious layering or oil droplet floating could be obtained. After pH correction, the pH of the resulting samples could be controlled between 5.2 and 5.8, the average particle size was within the range of 90–160 nm, and the PDI was not higher than 0.25. The process range of oil phase mixing temperature 45-65℃, high-speed shearing 8000-12000 rpm for 3-8 min, and high-pressure homogenization 80-120 MPa for 3-5 times can be used to prepare the nanoemulsion of this invention.

[0079] Example 11: Optimization Experiment of Representative Combination Prescriptions Based on Three Factors and Three Levels Based on the results of single-factor screening and process parameter verification in Examples 5-10, the amount of Sacha inchi oil (A), emulsifier combination level (B), and homogenization pressure (C), which have a significant impact on nanoemulsion particle size, PDI, and α-linolenic acid retention, were selected as the main factors for investigation. A representative combination formulation optimization experiment with three factors and three levels was conducted. The factor levels are shown in Table 8, and the experimental design and results are shown in Table 9.

[0080] Table 8. Factor Level Table for Three-Factor, Three-Level Prescription Optimization Experiment

[0081] Table 9. Optimization Experimental Design and Results of Representative Combination Prescriptions Based on Three Factors and Three Levels

[0082] Based on the comprehensive evaluation results of average particle size, PDI, α-linolenic acid retention in the peel, and system stability, it is evident that when the amount of Sacha involucrata oil is 3.50%, the emulsifier combination level is 3.00%, and the homogenization pressure is 100 MPa, the resulting nanoemulsion particle size is approximately 100–105 nm, the PDI is not higher than 0.25, and the α-linolenic acid retention in the peel is relatively high, resulting in superior overall performance. Therefore, the optimal formulation and process conditions are determined as follows: Sacha involucrata oil 3.50%, emulsifier combination level 3.00%, including 2.00% lecithin, 1.00% polyglycerol-6 oleate, 12.00% coffee fruit peel extract, 4.00% glycerol, homogenization pressure 100 MPa, and homogenization times 3.

[0083] Example 12 Preparation of a skin care nanoemulsion containing Sacha inchi oil and coffee pericarp extract Based on the screening results of Examples 5-11 above, skin care nanoemulsions were prepared under optimal conditions. The formula is shown in Table 10, and the preparation method is the same as in Example 4.

[0084] Table 10 Preferred Nanoemulsion Formulations

[0085] The prepared nanoemulsions exhibited uniform appearance, with an average particle size of 102.6 ± 3.5 nm, a PDI of 0.21 ± 0.02, a zeta potential of -28.4 ± 2.1 mV, and a pH of 5.62 ± 0.08. No stratification was observed after centrifugation at 4000 rpm for 30 min. After being placed at 4℃, 25℃, and 40℃ for 30 days, the particle size increase rate was less than 5% in each case. No significant demulsification, stratification, or oil droplet floating was observed after six freeze-thaw cycles at -5℃ and 40℃.

[0086] Example 13: pH Verification of Finished Product To support the pH range of 5.2–5.8 for the finished product of this invention, and to demonstrate that a stable, weakly acidic nanoemulsion can still be obtained through a buffer system even when the pH of the coffee fruit peel extract itself is low, a pH gradient verification of the finished product was conducted based on the preferred low-oil-phase, refreshing nanoemulsion formulation described in Example 12, by only changing the target pH of the aqueous phase. The coffee fruit peel extract used was the raw material prepared in Example 1, and its measured pH was 4.12.

[0087] The specific method is as follows: Nanoemulsions were prepared according to the formulation and preparation method of Example 12. The pH of the aqueous phase was adjusted to 5.2, 5.4, 5.6, and 5.8, respectively; the oil phase mixing temperature was 60℃; the high-speed shearing condition was 10,000 rpm for 6 min; and the high-pressure homogenization condition was 100 MPa for 3 cycles. After the samples were cooled to room temperature and degassed, the pH, average particle size, PDI, and centrifugal stability of the finished product were measured. The results are shown in Table 11.

[0088] Table 11 Results of pH gradient validation of finished product

[0089] As shown in Table 11, although the pH of the coffee fruit peel extract solution itself is 3.80–4.60, after adjusting the aqueous phase using a citric acid-sodium citrate buffer system and performing necessary corrections in the final product stage, the pH of the resulting nanoemulsion can stably fall within the range of 5.2–5.8. The average particle size of each group of samples is within the range of 90–160 nm, and the average PDI value is not higher than 0.25. After centrifugation at 4000 rpm for 30 min, no stratification, flocculation, or obvious oil droplet floating was observed. The results indicate that the pH range of 5.2–5.8 for the final product is suitable for the low-oil-phase, refreshing Sacha Inchi oil-coffee fruit peel extract water-in-oil skincare nanoemulsion of this invention.

[0090] Comparative Example 1: Sacha inchi oil nanoemulsion without coffee peel extract In this formulation, purified water is used in place of an equal amount of coffee fruit peel extract, and the remaining components and preparation process are the same as in Example 12.

[0091] Comparative Example 2: Ordinary emulsion without high-pressure homogenization The prescription is the same as in Example 12, but only high-speed shearing at 10,000 rpm for 6 min is used, without high-pressure homogenization.

[0092] Comparative Example 3: Coffee pericarp extract emulsion system without Sacha indica oil.

[0093] In this formulation, medium-chain triglycerides are used to replace sacha in equal amounts with sacha in fruit oil. The remaining components and preparation process are the same as in Example 12.

[0094] Comparative Example 4: System without phospholipid emulsifiers Lecithin was removed from the prescription and replaced with purified water; the remaining components and preparation process were the same as in Example 12.

[0095] The basic properties of the samples obtained from each comparative example are shown in Table 12.

[0096] Table 12 Comparison of properties between Example 12 and Comparative Examples 1-4

[0097] As shown in Table 12, high-pressure homogenization and phospholipid emulsifiers play an important role in the formation of stable nanoemulsions; the addition of coffee fruit peel extract helps to improve the overall stability of the system and the subsequent skin delivery effect.

[0098] Experimental Example 1: In vitro transdermal and intradermal retention test In vitro transdermal and intradermal retention were evaluated using a Franz diffusion cell. Skin from the back of Bama miniature pigs was harvested, subcutaneous fat removed, with the stratum corneum facing the donor chamber and the dermis facing the receiver chamber. The receiver solution was pH 7.4 PBS, the receiver chamber volume was 7 mL, the effective diffusion area was 2.33 cm², the temperature was maintained at 32 ± 0.5 °C, and the magnetic stirring speed was 600 rpm. 1.0 g of sample was added to each donor chamber, and samples were collected at 2, 6, 12, and 24 h. After the experiment, the skin was removed, residual sample was washed off, and the sample was minced, homogenized in a methanol-water mixture, and centrifuged to collect the supernatant. α-Linolenic acid was determined by gas chromatography, and chlorogenic acid was determined by high-performance liquid chromatography.

[0099] The skin delivery results of each sample in Example 12 and Comparative Examples 1-3 after 24 hours are shown in Table 13.

[0100] Table 13 Results of in vitro skin delivery

[0101] As shown in Table 13, compared with ordinary emulsions and ordinary sacha inchi oil suspensions, the preferred nanoemulsion of the present invention increases the retention of α-linolenic acid in the skin; compared with Comparative Example 1 which does not contain coffee peel extract, the retention of α-linolenic acid in the skin in Example 12 is further increased, indicating that coffee peel extract has the effect of promoting the local retention of oil phase active substances in the skin in this nanoemulsion system.

[0102] Example 2: Evaluation of in vitro antioxidant activity To illustrate the antioxidant activity basis of sacha inchi oil as the active component of the oil phase of the present invention, the superoxide radical scavenging and hydroxyl radical scavenging of sacha inchi oil raw material, coffee peel extract, Example 12 and Comparative Examples 1-2 were first evaluated.

[0103] The experimental method is as follows: Sample setup: Examples 12, Comparative Example 1, and Comparative Example 2 were all diluted 1000 times with purified water before measurement. Based on a formulation density of approximately 1.0 g / mL, the final concentration of the formulation after a 1:1000 dilution was approximately 1.0 mg / mL. In Examples 12 and Comparative Example 2, the amount of *Corydalis acetosa* oil was 3.50%, and the amount of coffee pericarp extract was 12.00%. Therefore, the final concentration of *Corydalis acetosa* oil in the 1:1000 dilution was approximately 35.0 μg / mL, and the final concentration of coffee pericarp extract was approximately 120 μg / mL. In Comparative Example 1, the amount of *Corydalis acetosa* oil was 3.50%, and it did not contain coffee pericarp extract. Therefore, the final concentration of *Corydalis acetosa* oil in the 1:1000 dilution was approximately 35.0 μg / mL, and the final concentration of coffee pericarp extract was 0. The coffee pericarp extract sample was converted to an equivalent amount based on its addition ratio in the nanoemulsion of Example 12, resulting in a final concentration of approximately 120 μg / mL. Sacha inchi oil was pre-dispersed with a small amount of ethanol and then diluted to original volume concentrations of 6.25 nL / mL, 25 nL / mL, and 100 nL / mL. Based on the measured density of sacha inchi oil (0.95 g / mL), its mass concentrations were 5.94 μg / mL, 23.75 μg / mL, and 95.00 μg / mL, respectively. The final ethanol concentration was kept consistent in all sample systems, and corresponding solvent blanks were set. Since coffee peel extract and nanoemulsion samples inherently possess color or turbidity, sample blanks were simultaneously set during the measurements to eliminate interference from the sample's own absorbance.

[0104] Hydroxyl radical scavenging rate: The Fenton reaction system was used. An appropriate amount of the sample solution prepared according to the above concentrations was taken. In a reaction tube, 1.0 mL of 9.0 mmol / L FeSO4 solution, 1.0 mL of 9.0 mmol / L salicylic acid-ethanol solution, 1.0 mL of sample diluent, and 1.0 mL of 8.8 mmol / L H2O2 solution were added sequentially. After mixing, the mixture was reacted in a water bath at 37℃ for 30 min, and the absorbance (A_sample) was measured at 510 nm. A_blank was measured using purified water instead of H2O2 solution, and A_control was measured using purified water instead of sample solution. Hydroxyl radical scavenging rate (%) = [1 - (A_sample - A_blank) / A_control] × 100%. Each sample was measured in triplicate.

[0105] Superoxide anion radical scavenging rate: The pyrogallol auto-oxidation method (Marklund & Marklund, 1974) was used. An appropriate amount of the sample solution prepared according to the above concentration was taken. 4.5 mL of 50 mmol / L Tris-HCl buffer (pH 8.2) and 1.0 mL of sample diluent were added sequentially to the reaction tube. After incubating at 25°C for 20 min, 0.4 mL of 25 mmol / L pyrogallol solution (prepared with 10 mmol / L HCl) was added. After mixing, the reaction was incubated at 25°C for 5 min. The reaction was terminated by adding 1.0 mL of 8 mol / L HCl, and the absorbance was measured at 325 nm. Purified water was used as a blank control instead of the sample. Each sample was measured in triplicate, and the results are expressed as scavenging rate (%).

[0106] The results are shown in Table 14. Sacha inchi oil, prepared by volume concentration, showed certain antioxidant activity at mass concentrations of 5.94 μg / mL, 23.75 μg / mL, and 95.00 μg / mL after conversion based on the measured density of 0.95 g / mL. Specifically, the superoxide radical scavenging rates were 10.96±1.11%, 23.53±1.42%, and 30.27±0.78%, respectively, while the hydroxyl radical scavenging rates were 19.95±8.21%, 32.98±2.45%, and 32.88±4.42%, respectively. In Example 12, under a 1:1000 dilution condition, i.e., a final concentration of approximately 1.0 mg / mL, and a final concentration of approximately 35.0 μg / mL of Sacha involucrata oil and approximately 120 μg / mL of coffee pericarp extract, the superoxide radical scavenging rate was 38.6 ± 1.5%, and the hydroxyl radical scavenging rate was 42.8 ± 2.6%. The antioxidant effect was better than that of Comparative Example 1 without coffee pericarp extract and Comparative Example 2 without high-pressure homogenization, indicating that Sacha involucrata oil and coffee pericarp extract can jointly enhance the in vitro antioxidant effect in the nanoemulsion system.

[0107] Table 14 Results of Antioxidant Activity Evaluation

[0108] Note: The Sacha inchi oil raw material was originally prepared according to volume concentration and converted to mass concentration based on the measured density of 0.95 g / mL; the final concentrations of Sacha inchi oil and coffee pericarp extract in Examples 12, Comparative Examples 1 and 2 were calculated based on the final concentration of the formulation and the mass percentage of the prescription. The final concentration of coffee pericarp extract is the mass concentration calculated based on the amount of extract added.

[0109] Example 3: Evaluation of anti-inflammatory and soothing in vitro activities To illustrate the basis of the anti-inflammatory and soothing activity of Sacha inchi oil as the active component of the oil phase in this invention, the anti-inflammatory activity of Sacha inchi oil raw material, Sample 12 and Comparative Examples 1-2 was evaluated in an LPS-induced RAW264.7 cell inflammation model.

[0110] The experimental method is as follows: Sample setup: Examples 12, Comparative Example 1, and Comparative Example 2 were diluted according to the formulation mass concentration. The final concentration of the formulation was approximately 1.0 mg / mL at a 1:1000 dilution and approximately 0.5 mg / mL at a 1:2000 dilution. In Example 12, the formulation amount of Sacha inchi fruit oil was 3.50% and the formulation amount of coffee pericarp extract was 12.00%. Therefore, the final concentration of Sacha inchi fruit oil at a 1:1000 dilution was approximately 35.0 μg / mL and the final concentration of coffee pericarp extract was approximately 120 μg / mL; the final concentrations at a 1:2000 dilution were approximately 17.5 μg / mL and 60 μg / mL, respectively. Comparative Example 1 did not contain coffee pericarp extract; Comparative Example 2 had the same formulation as Example 12 but was not homogenized under high pressure. Sacha indica oil was pre-dispersed in small amounts of ethanol or DMSO before being added to the culture system, with initial volume concentrations of 6.25 nL / mL, 25 nL / mL, and 100 nL / mL, respectively. Based on the measured density of sacha indica oil (0.95 g / mL), its mass concentrations were calculated to be 5.94 μg / mL, 23.75 μg / mL, and 95.00 μg / mL, respectively. The final solvent concentration was kept consistent in all oil-containing samples, and corresponding solvent blanks were included.

[0111] A lipopolysaccharide (LPS)-induced macrophage inflammation model was established in RAW264.7 mice. RAW264.7 cells were cultured at a rate of 1 × 10⁻⁶ cells / cells. 5 Cells were seeded per well in 96-well plates and cultured in DMEM medium containing 10% fetal bovine serum at 37°C and 5% CO2 until adherent. A blank control group (medium only), a model group (containing 1 μg / mL LPS), a sample group (containing 1 μg / mL LPS + serially diluted test samples), and a positive control group (containing 1 μg / mL LPS + dexamethasone) were established. Cells were pretreated with the test samples for 1 h, then stimulated with LPS and cultured for another 24 h.

[0112] Cell viability assessment (CCK-8 assay): Before the determination of inflammatory factors, the potential cytotoxicity of the test samples to RAW264.7 cells was evaluated using the CCK-8 assay to exclude the apparent decrease in inflammatory factors due to cell death. 10 μL of CCK-8 solution was added to each well, and the cells were incubated at 37°C for 1–2 h before the absorbance was measured at 450 nm. Cells with viability below 80% were not included in the analysis of inflammatory factor assay results.

[0113] TNF-α and IL-6 content determination: The content of TNF-α and IL-6 in cell culture supernatant was determined using an ELISA kit, strictly following the kit instructions. Each sample was tested in triplicate, and a standard curve was plotted using standards to calculate the content and inhibition rate of each inflammatory factor.

[0114] In Example 12, Comparative Example 1, Comparative Example 2, and all concentration groups of Sacha Inchi oil raw materials, CCK-8 cell viability was simultaneously measured. Cell viability in each group was calculated with the LPS model group as 100%. Sample concentrations with cell viability below 80% were not included in the analysis of inflammatory factor inhibition rate.

[0115] The results are shown in Table 15. RAW264.7 cells secreted TNF-α and IL-6 after LPS induction. Sacha inchi oil was prepared at volume concentrations, and after conversion from the measured density of 0.95 g / mL, the mass concentrations were 5.94 μg / mL, 23.75 μg / mL, and 95.00 μg / mL. Cell viability at these concentrations was 103.6±4.1%, 101.4±4.3%, and 103.1±4.6%, respectively, all above 80%, indicating no significant cytotoxicity within this concentration range. The inhibition rates of TNF-α by sacha inchi oil at the above concentrations were 39.93%, 47.50%, and 68.17%, respectively, and the inhibition rates of IL-6 were 51.29%, 38.30%, and 44.59%, respectively. The inhibition rate of TNF-α increased with increasing sacha inchi oil concentration, while the inhibition rate of IL-6 did not show a completely linear concentration-dependent relationship, but all concentration groups showed some inhibitory effect. In Example 12, Comparative Example 1, and Comparative Example 2, cell viability was also above 80%, and their inflammatory factor inhibition results could be included in the comparative analysis. In Example 12, under a 1:1000 dilution condition (i.e., a final concentration of approximately 1.0 mg / mL for the formulation, a final concentration of Sacha inchi oil equivalent to the prescription of approximately 35.0 μg / mL, and a final concentration of approximately 120 μg / mL for the coffee pericarp extract), cell viability was 105.6 ± 4.8%, and the inhibition rates of TNF-α and IL-6 were 55.8 ± 3.4% and 47.6 ± 3.1%, respectively. Its inhibitory effect was superior to Comparative Example 1 (which did not contain coffee pericarp extract) and Comparative Example 2 (which did not undergo high-pressure homogenization), indicating that the composite nanoemulsion system has good soothing-related in vitro activity under conditions without significant cytotoxicity. Table 15: Anti-inflammatory and soothing evaluation results.

[0116] Note: The Sacha inchi oil raw material group was originally prepared according to volume concentration, and converted to mass concentration based on the measured density of Sacha inchi oil of 0.95 g / mL; the final concentrations of Sacha inchi oil and coffee pericarp extract in Examples 12, Comparative Examples 1 and 2 were calculated based on the final concentration of the formulation and the mass percentage of the prescription. Cell viability was calculated with the LPS model group as 100%.

[0117] Example 4: Evaluation of Anti-corrosion Auxiliary Effect Take the basal emulsions from Example 12, Comparative Example 1, and blank, and inoculate them with Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans, respectively. The initial inoculum size is 10. 5 ~10 6 The CFU / g microorganisms were stored at 25℃, and samples were taken at 7, 14, and 28 days to evaluate the decreasing trend of microorganisms in the system. The results are shown in Table 16.

[0118] Table 16 Corrosion Prevention Auxiliary Evaluation Results

[0119] As shown in Table 16, Example 12, containing coffee fruit peel extract, exhibited a better inhibitory effect on microorganisms than Comparative Example 1, which did not contain coffee fruit peel extract. This result indicates that polyphenols, organic acids, and other components in coffee fruit peel extract can play a preservative-enhancing role in the system; however, in actual products, appropriate amounts of compliant preservatives can still be added according to regulations and product requirements.

[0120] Experimental Example 5: Evaluation of Biphasic Simultaneous Delivery of α-Linolenic Acid and Chlorogenic Acid To demonstrate that the nanoemulsion of this invention not only improves the dispersibility of the oil phase Sacha inchi oil, but also simultaneously enhances the local retention of the oil phase representative indicator α-linolenic acid and the aqueous phase representative indicator chlorogenic acid in the skin, the Franz diffusion cell method of Experimental Example 1 was used to determine the 24-hour intradermal retention of α-linolenic acid and chlorogenic acid in different systems. The different system groups are shown in Table 17.

[0121] The synchronous delivery index is calculated using the following formula: Synchronous delivery index = 0.5 × (the amount of α-linolenic acid retained in the skin of a certain group / the amount of α-linolenic acid retained in the skin of the present invention group) + 0.5 × (the amount of chlorogenic acid retained in the skin of a certain group / the amount of chlorogenic acid retained in the skin of the present invention group).

[0122] For groups that do not contain the corresponding indicator, this item is recorded as 0. The synchronous delivery index for this invention is defined as 1.00.

[0123] Table 17. Delivery results of α-linolenic acid and chlorogenic acid in transdermal assays using different systems.

[0124] The results are shown in Table 17. The simultaneous delivery index was defined as 1.00, using the normalized composite value of the intradermal retention of α-linolenic acid and chlorogenic acid in the present invention group (prepared in Example 12). The other groups were calculated using the same formula. For groups that did not contain the corresponding indicator substances of α-linolenic acid or chlorogenic acid, the missing item was recorded as 0. As can be seen from Table 17, the simultaneous delivery index of the present invention group was the highest, indicating that the present invention's nanoemulsion not only improved the intradermal retention of α-linolenic acid in the oil phase, but also improved the intradermal retention of chlorogenic acid components in the aqueous phase. Although the aqueous phase of coffee peel extract alone or the Sacha inchi oil nanoemulsion without coffee peel extract could deliver a single indicator substance, its simultaneous delivery index was significantly lower than that of the present invention group due to the lack of another phase indicator substance. This indicates that the nano-interface system of the present invention has the advantage of simultaneous delivery of biphase active ingredients.

[0125] Example 6: Evaluation of Comprehensive Physical and Oxidative Stability The nanoemulsion obtained in Example 12 was subjected to low-temperature, room-temperature, accelerated, centrifugal, and freeze-thaw tests. Initially, appearance, average particle size, PDI, zeta potential, and pH were measured. Samples were placed at 4℃, 25℃, and 40℃ for 30 days, and at the end of the tests, the presence of stratification, demulsification, flocculation, precipitation, or significant discoloration was observed, and the particle size change rate was measured. Additionally, samples were placed at 45℃ for 7 days to evaluate short-term thermal storage stability; mechanical stability was evaluated by centrifugation at 4000 rpm for 30 min; and six freeze-thaw cycles were performed, with each cycle consisting of -5℃ / 40℃.

[0126] Table 18. Overall stability evaluation results of the nanoemulsion in Example 12

[0127] As shown in Table 18, the average particle sizes of the preferred nanoemulsion of this invention after storage at 4℃, 25℃, and 40℃ for 30 days were 103.4±3.2 nm, 104.5±3.7 nm, and 106.9±4.1 nm, respectively, with particle size growth rates all below 5% and PDI values ​​not exceeding 0.23. After short-term heat storage at 45℃ for 7 days, centrifugation at 4000 rpm for 30 min, and 6 freeze-thaw cycles at -5℃ / 40℃, the system still did not show obvious stratification, demulsification, or oil droplet floating, and the particle size change rate was less than 10%. After being placed at 40℃ for 30 days, the peroxide value increased from 3.80±0.16 meq O2 / kg to 4.50±0.23 meq O2 / kg, with a growth rate of 18.5%, which was lower than the 29.6% of the control group without coffee fruit peel extract. The results showed that the nanoemulsion had both good physical and oxidative stability. In addition to participating in interfacial stabilization, the coffee peel extract could also provide some oxidative protection for sacha inchi oil, which is rich in polyunsaturated fatty acids.

[0128] Example 7: In vitro skin irritation evaluation Evaluation of irritation to reconstructed human epidermis. Following the in vitro skin irritation testing approach described in OECD TG 439, the EpiSkin™ SM reconstructed human epidermis model or an equivalent human reconstructed epidermis model validated by OECD TG 439 was used for evaluation. The experiment included a negative control, a positive control, a blank matrix control, and the sample group from Example 12, with three replicates in each group. The negative and positive controls were set up according to the model instructions. Samples were treated according to the sample loading amount, exposure time, and post-culture time specified in the model instructions. Tissue viability was determined using the MTT assay, and the coefficient of variation within each group was calculated. When the control effectiveness met the model quality standards, a sample with an average tissue viability greater than 50% was considered non-irritating, and a viability less than or equal to 50% was considered irritating. Results are shown in Table 19.

[0129] Table 19 Record of Irritation Evaluation Results for Reconstructed Human Epidermis

[0130] The results showed that the survival rate of the negative control tissue was 100.0±4.7%, and that of the positive control was 4.2±0.6%. The coefficients of variation for each group were all below 18%, indicating that the model control was effective. The tissue survival rates of the blank matrix and Example 12 were 96.8±3.9% and 88.9±3.8%, respectively, both higher than the 50% threshold. Therefore, under the conditions of this experiment, they were determined to be non-irritating.

[0131] Application Example 1: Preparation of Low-Additive Skin Care Essence Water Take 0.50% of the nanoemulsion obtained in Example 12, 3.00% glycerin, 3.00% 1,3-propanediol, 0.30% panthenol, 0.03% sodium hyaluronate, and an appropriate amount of preservative, with the remainder being purified water. First, pre-disperse sodium hyaluronate in glycerin and 1,3-propanediol, add some purified water, and stir until fully swollen and form a homogeneous aqueous phase; then add panthenol, preservative, and the remaining purified water, and stir at low speed until homogeneous; subsequently, add the nanoemulsion obtained in Example 12, stir at low speed until the system is homogeneous, adjust the pH to 5.5-6.0, and defoam, to obtain a skin care essence water containing nanoemulsion of Sacha indica oil and coffee peel extract.

[0132] The resulting essence water was a clear to slightly milky white homogeneous liquid, with no obvious oil droplets, flocculation, or sediment. After being placed at 25°C for 30 days, no obvious layering, sedimentation, or oil droplet floating was observed, and the appearance remained stable. This result indicates that the nanoemulsion of the present invention can be added as a functional additive phase to water-based skin care products at a low addition amount of 0.50%.

[0133] Application Example 2: Preparation of Skin Care Essence Take 20.00% of the nanoemulsion obtained in Example 12, add 3.00% glycerin, 3.00% 1,3-propanediol, 0.05% sodium hyaluronate, 0.10% xanthan gum, 0.50% panthenol, and an appropriate amount of preservative, with the remainder being purified water. Pre-disperse xanthan gum and sodium hyaluronate in glycerin, add purified water and stir to swell, then add 1,3-propanediol, panthenol, and the preservative. Finally, add the nanoemulsion from Example 12, stir at low speed until homogeneous, adjust the pH to 5.2–5.8, and defoam to obtain a skincare essence containing sacha inchi oil and coffee peel extract nanoemulsion.

[0134] The resulting serum has a uniform appearance, with no obvious oil droplets or sediment, and a refreshing feel on the skin. It can be used in anti-oxidant and soothing skincare products.

[0135] Application Example 3: Preparation of Skin Lotion Take 30.00% of the nanoemulsion obtained in Example 12, add 2.00% squalane, 1.00% cetearyl alcohol, 4.00% glycerin, 0.15% carbomer, appropriate amount of triethanolamine, appropriate amount of preservative, and the remainder is purified water. First, disperse the carbomer in water and allow it to swell completely. Add glycerin and preservative and stir evenly. Separately, heat the squalane and cetearyl alcohol to 70°C to melt them and add them to the aqueous phase. Shear emulsify and cool to below 40°C. Then add the nanoemulsion from Example 12 and stir evenly at low speed. Adjust the pH to 5.2-5.8 to obtain the skin care lotion.

[0136] The resulting lotion can be used for daily care of dry, rough skin.

[0137] Application Example 4: Preparation of Skin Cream Take 25.00% of the nanoemulsion obtained in Example 12, add 4.00% caprylic / capric triglyceride, 2.00% cetearyl alcohol, 1.50% glyceryl stearate, 5.00% glycerin, 2.00% betaine, 0.20% carbomer, and an appropriate amount of preservative, with the remainder being purified water. Melt the oil phase component at 75°C, heat the aqueous phase component to 75°C and stir until homogeneous. Add the oil phase to the aqueous phase and emulsify using high-speed shearing. After cooling to below 45°C, add the nanoemulsion from Example 12, stir until homogeneous, adjust the pH to 5.2–5.8, and defoam to obtain the skin cream.

[0138] The resulting face cream can be used as an antioxidant and soothing daily skincare product.

[0139] Comparative Example 5: Comparison with publicly available Sacha Inchi oil microemulsions or nanosystems This embodiment compares the present invention with publicly available Sacha Inchi oil microemulsions, microemulsions, nano-infusion solutions, and nano-essence solutions to examine the comprehensive effects of the present invention on interface stability, oxidative protection, and local skin retention after the introduction of coffee peel extract.

[0140] Comparative Example A was prepared according to the Sacha indica oil microemulsion technology disclosed in CN109276483A / CN109276483B, which involves forming a microemulsion system with Sacha indica oil, conventional surfactants, co-surfactants, and water. For ease of comparison within the same Franz system, the amount of Sacha indica oil was uniformly converted to 3.50%. Comparative Example B was prepared according to the oil-in-water Sacha indica oil microemulsion technology disclosed in CN108685767A, which involves constructing a clear microemulsion system using Tween-80 / Span-80 or similar nonionic surfactants and co-surfactants. Comparative Example C was prepared according to the Sacha indica oil-containing nano-system delivery liquid technology disclosed in CN107412014A, which involves constructing a nano-delivery liquid system with Sacha indica oil, natural essential oils, emulsifiers, co-emulsifiers, moisturizers, antioxidants, preservatives, and water. Comparative Example D was prepared according to the Sacha indica oil-containing nano-essence technology disclosed in CN106667805A. The above comparative examples did not include coffee fruit peel extract; except for the emulsifiers, co-emulsifiers and excipients necessary in the original technical concept, the other testing conditions were consistent with those of the present invention.

[0141] It should be noted that the aforementioned patents mainly disclose the composition and stability schemes of Sacha Inchi oil microemulsions or nanosystems, but do not disclose the intradermal retention of α-linolenic acid or chlorogenic acid under the Franz diffusion cell conditions in this embodiment. Therefore, the skin delivery data in Table 20 are data obtained under uniform experimental conditions after preparing control samples according to the corresponding disclosed technical solutions.

[0142] Table 20 Comparison results with publicly available Sacha Inchi oil microemulsions or nanosystems

[0143] As can be seen from the results in the table, samples prepared using existing Sacha Inchi oil microemulsion or nanosystem techniques can achieve smaller particle sizes or better appearance stability, but their α-linolenic acid retention and oxidative stability are inferior to those of the group presented in this invention. In particular, compared to F6, both use the same emulsifier system, differing only in the addition of coffee peel extract. The α-linolenic acid retention in the group presented in this invention is significantly increased, indicating that the coffee peel extract is not a common aqueous diluent, but rather participates in interface construction, antioxidant protection, and local delivery promotion in this nanoemulsion.

[0144] Comparative Example 6: Comparison of different aqueous phase substitution systems for natural polyphenols To investigate the technical effects of coffee pericarp extract compared to other natural polyphenol aqueous phases, the following were used: Sacha inchi oil (3.50%), lecithin (2.00%), polyglycerol-6 oleate (1.00%), glycerol (4.00%), homogenization pressure (100 MPa), and homogenization cycles (3). The coffee pericarp extract was replaced with green tea extract, grape seed extract, rosemary extract, and pure chlorogenic acid solution, all with similar total polyphenol content. The average particle size, PDI, and α-linolenic acid retention in the pericarp were then examined.

[0145] Table 21 Results of various indicators of sacha inchi oil nanoemulsions with different natural polyphenol aqueous phases

[0146] The results showed that the total polyphenol content was similar across all groups, but the coffee pericarp extract group had a smaller average particle size, a lower PDI, and the highest α-linolenic acid retention within the pericarp. While the pure chlorogenic acid group had a considerable phenolic acid content, its promoting effect on the local retention of active substances in the oil phase was weaker due to the lack of polysaccharides, pectin-like substances, and complex weakly acidic components found in the coffee pericarp extract. These results indicate that the technical effects of coffee pericarp extract cannot be achieved simply by replacing single polyphenols or chlorogenic acid.

[0147] Comparison Example 7: Coffee pericarp extract compared with commonly used delivery-enhancing components To compare the local skin delivery efficacy and mildness of coffee fruit peel extract and commonly used delivery enhancers in a sacha inchi oil nanoemulsion system, the following parameters were kept constant: sacha inchi oil 3.50%, lecithin 2.00%, polyglycerol-6 oleate 1.00%, glycerol 4.00%, and homogenization conditions. Coffee fruit peel extract, azone, propylene glycol, polysorbate-80, or no delivery enhancer were used as variables. Cell viability was evaluated using the CCK-8 assay, and the intradermal retention of α-linolenic acid was determined using the Franz diffusion cell method described in Example 1.

[0148] Table 22 Results of various indicators of Safflower oil nanoemulsions with different penetration enhancers

[0149] The results showed that the azone group increased subcutaneous penetration, but cell viability decreased significantly; the coffee fruit peel extract group achieved the highest intradermal retention while maintaining high cell viability. For skincare products, local retention of active ingredients in the stratum corneum and epidermis is more in line with the purpose of soothing and antioxidant care.

[0150] As can be seen from the above examples, comparative examples, and experimental results, this invention uses Sacha inchi oil as the oil phase and coffee pericarp extract with a specific range of soluble solids, total polyphenols, and total polysaccharides as the functional aqueous phase. An emulsifying interface is constructed using lecithin and polyglycerol-6 oleate, and the mixture is then homogenized under high pressure to prepare a skin-care nanoemulsion. Single-factor screening and three-factor, three-level representative combination formulation optimization experiments show that the preferred formulation is 3.50% Sacha inchi oil, 12.00% coffee pericarp extract, 2.00% lecithin, 1.00% polyglycerol-6 oleate, 4.00% glycerin, and a citric acid-sodium citrate buffer system of 0.05%–0.20%. The nanoemulsion prepared by the formulation through high-speed shearing at 10,000 rpm for 6 min and high-pressure homogenization at 100 MPa three times had an average particle size of 102.6±3.5 nm, a PDI of 0.21±0.02, and a pH of 5.62±0.08, and exhibited good physical stability, oxidative stability, and skin compatibility.

[0151] In vitro transdermal assays, evaluations of antioxidant activity, anti-inflammatory and soothing effects, simultaneous delivery of biphasic active ingredients, and cell compatibility showed that the nanoemulsion of this invention can enhance the local retention of oil-phase α-linolenic acid and aqueous-phase chlorogenic acid in the skin, exhibiting antioxidant and soothing in vitro activities. Furthermore, it demonstrated good cell compatibility under the conditions described in this experiment, and the reconstructed human epidermal model was determined to be non-irritating. Compared with publicly available sacha inchi oil microemulsions or nanosystems, this invention has significant advantages in terms of α-linolenic acid retention in the skin and oxidative stability.

[0152] The substitution test and comparative test of delivery-enhancing components of coffee fruit peel extract further proved that the technical effect of coffee fruit peel extract cannot be obtained by simply replacing a single polyphenol or conventional penetration enhancer. The synergistic effect of its multiple components, such as polysaccharides, polyphenols, and organic acids, is the key to achieving simultaneous delivery of biphasic active ingredients, interfacial stability, and mildness.

[0153] In summary, the skincare nanoemulsion provided by this invention has a clearly defined composition, scalable process, and clear stability and efficacy indicators, and can be used in anti-oxidant and soothing skincare products.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A skincare nanoemulsion containing sacha inchi oil and coffee fruit peel extract, characterized in that, By weight percentage, it consists of the following components: 2.0%–5.0% Sacha inchi oil, 8%–16.0% coffee fruit peel extract, 1.5%–2.5% lecithin, 1%–1.5% polyglycerol-6 oleate, 2.0%–4.0% glycerin, pH adjuster, and the balance being water; the amount of pH adjuster is such that the pH of the skin care nanoemulsion is adjusted to 5.2–5.

8. The coffee fruit peel extract contains 3.0%–6.0% soluble solids, 1.0–2.5 mg / mL total polyphenols (calculated as gallic acid equivalent), and 2.0–8.0 mg / mL total polysaccharides (calculated as glucose equivalent). The average particle size of the skin care nanoemulsion is 90–160 nm, and the PDI is ≤0.

25.

2. The skin-care nanoemulsion according to claim 1, characterized in that, The sacha inchi oil contains 42.0%–52.0% α-linolenic acid, 30.0%–40.0% linoleic acid, and 6.0%–12.0% oleic acid, and has a peroxide value ≤10 meq O2 / kg.

3. The skin-care nanoemulsion according to claim 1, characterized in that, The coffee fruit peel extract is prepared by water extraction, filtration and vacuum concentration of coffee fruit peel, with a pH of 3.80 to 4.60 and a chlorogenic acid content of 0.20 to 0.80 mg / mL.

4. The skin-care nanoemulsion according to claim 1, characterized in that, The lecithin is soybean lecithin; the pH adjuster is a citric acid-sodium citrate buffer system.

5. The skin-care nanoemulsion according to claim 1, characterized in that, By weight percentage, it consists of the following components: 3.5% Sacha inchi oil, 12.0% coffee fruit peel extract, 2.0% lecithin, 1.0% polyglycerol-6 oleate, 4.0% glycerin, a citric acid-sodium citrate buffer system, and the balance being water; the amount of the citric acid-sodium citrate buffer system is used to adjust the pH of the skin care nanoemulsion to 5.2-5.

8.

6. A method for preparing the skin-care nanoemulsion according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Mix sacha inchi oil and lecithin at 45-65°C to form an oil phase; (2) Mix coffee fruit peel extract, polyglycerol-6 oleate, glycerol, pH adjuster and water, and adjust the pH to 5.2-5.8 to form an aqueous phase; (3) The oil phase is slowly added to the aqueous phase and sheared at high speed for 3 to 8 minutes at 8000 to 12000 rpm to obtain a crude emulsion; (4) The crude milk is homogenized under high pressure at 80-120 MPa for 3-5 times, cooled to room temperature, pH adjusted to 5.2-5.8 and defoamed to obtain the final product.

7. The method according to claim 6, characterized in that, The high-speed shearing conditions were 10,000 rpm for 6 minutes, and the high-pressure homogenization conditions were 100 MPa for 3 cycles.

8. A skincare product, characterized in that, The product includes the skin care nanoemulsion as described in any one of claims 1 to 5 and cosmetically acceptable excipients, wherein the skin care nanoemulsion is present in the skin care product at a mass percentage of 0.5% to 30%.

9. The skincare product according to claim 8, characterized in that, The skincare products mentioned are essence water, serum, lotion, or face cream.

10. The use of the skin care nanoemulsion according to any one of claims 1 to 5 in the preparation of skin care products with antioxidant, anti-inflammatory and / or soothing effects.

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