Hibiscus sabdariffa extract capable of stably controlling oil and preparation method and application of Hibiscus sabdariffa extract

Abstract

The invention belongs to the field of plant extracts, and particularly relates to a roselle extract capable of stably controlling oil as well as a preparation method and application of the roselle extract. Dried calyx of roselle is used as a raw material, a semi-bionic extraction process of first alkali extraction and then acid extraction is adopted, alkali extraction is carried out for 2-4 h at the pH of 7.5-9.5 and the temperature of 35-40 DEG C, then acid extraction is carried out for 1-3 h at the pH of 2-4 and the temperature of 35-42 DEG C, extracting solutions are combined, then concentration and drying are carried out, and the roselle extract is obtained. According to the preparation method of the roselle extract, pure water extraction is conducted in the whole process, use of organic solvents is avoided, the process is simple, green and environmentally friendly, the stability of the extract is remarkably improved, meanwhile, high-content polyphenol and organic acid are reserved, and the roselle extract product achieves the efficient and long-acting oil control effect and is suitable for cosmetics.

Description

Technical Field

[0001] This invention belongs to the field of plant extracts, specifically relating to a stable and oil-controlling roselle extract, its preparation method, and its application. Background Technology

[0002] Roselle (Hibiscus sabdariffa L.), also known as hibiscus, is an annual herbaceous plant belonging to the genus Hibiscus in the Malvaceae family. It is hailed as the "plant ruby" due to its rich nutritional components and active substances. The calyx of the roselle flower is rich in polysaccharides, proteins, organic acids, various amino acids, natural vitamins, and minerals such as iron, calcium, and phosphorus, possessing extensive medicinal and skincare value. In the food industry, roselle extract has been shown to regulate blood pressure and improve sleep; in the cosmetics industry, it exhibits good skincare effects and significant tyrosinase inhibition capabilities, making it suitable for the preparation of whitening skincare agents.

[0003] However, existing methods for preparing hibiscus extract have some limitations. For example, Chinese patent CN111202779B discloses an acne-removing composition, the raw material of which includes hibiscus extract. The preparation of hibiscus extract involves pulverizing dried hibiscus, adding a 60%–85 wt% ethanol solution, ultrasonic-assisted extraction, transferring to a three-necked flask for heating and reflux extraction, filtering, and concentration under reduced pressure. Although the traditional ethanol extraction method can effectively extract anthocyanins, the resulting extract is prone to discoloration or deterioration in cosmetic applications due to changes in pH or fluctuations in storage temperature, affecting the stability and appearance of the product. In addition, existing technologies employ enzymatic hydrolysis, fermentation, or high-temperature extraction processes, such as the fermentation product filtrate obtained by lactic acid bacteria fermentation of hibiscus flowers disclosed in Chinese patent CN113208960B. However, these processes are not only complex and costly, but may also destroy some active ingredients, leading to reduced efficacy or insufficient stability of the extract.

[0004] As consumers increasingly demand higher levels of safety and efficacy in cosmetics, the development of plant extracts with stability and specific effects has become an important research direction for the industry. Summary of the Invention

[0005] To address the aforementioned technical problems, the first aspect of this invention provides a method for preparing a roselle extract with stable oil-controlling effects. This preparation method is simple to operate, low in cost, and environmentally friendly, and the resulting roselle extract exhibits high stability and excellent oil-controlling effects.

[0006] This invention provides a method for preparing hibiscus extract, comprising: Remove impurities from dried roselle calyxes, sift, and obtain roselle powder; Mix roselle powder and water, heat, stir well, then add alkaline solution to adjust the pH of the system to 7.5-9.5; Alkaline extraction for 2-4 hours, followed by filtration, collection of filter residue and first extract; Mix the filter residue with water, heat it, stir it evenly, and then add acid solution to adjust the pH of the system to 2-4. Acid extract for 1-3 hours, filter, and collect the second extract; Combine the first and second extracts, concentrate and dry.

[0007] As a feasible example, after merging the first and second extracts, an adsorbent can be added, the mixture stirred for 0.5-2 hours, filtered, and the decolorized and impurity-removed liquid collected; then concentrated and dried to obtain the roselle extract.

[0008] As an example of implementation, the sieve mesh size is 20-100 mesh.

[0009] Furthermore, the mesh size of the sieve is 40-80 mesh.

[0010] As an feasible example, after adding alkali, the pH of the system is adjusted to 8-9.

[0011] As an feasible example, the pH of the system is adjusted to 3-4 after adding acid.

[0012] As an example of implementation, the mass ratio of the roselle powder to water is 1:(5-10).

[0013] As an example of implementation, the roselle powder and water are mixed and then heated to a temperature of 35-40°C.

[0014] Furthermore, the mass ratio of the roselle powder to water is 1:8, and the heating temperature is 37°C.

[0015] As an example of implementation, the alkaline solution is an aqueous solution of NaOH, KOH, or Ca(OH)2.

[0016] As an example of implementation, the stirring rate of the alkali extraction is 400-800 rpm.

[0017] As an example of implementation, the filter residue and water are mixed and then heated to a temperature of 35-42°C.

[0018] As an example of implementation, the acid solution is an aqueous solution of hydrochloric acid or citric acid.

[0019] As an example of implementation, the adsorbent is activated carbon.

[0020] Furthermore, the amount of adsorbent used is 0.05-1% of the total mass of the first extract and the second extract.

[0021] The present invention also provides a roselle extract prepared by the above preparation method, wherein the roselle extract is prepared by the above preparation method.

[0022] As an example of implementation, the polyphenol content of the roselle extract is not less than 8%, further, the polyphenol content is 8-20%, and even further, the polyphenol content is 9-18%.

[0023] As an implementable example, the hibiscus extract has an organic acid content of not less than 15%, further, the organic acid content is 15-50%, and even further, the organic acid content is 21-44%.

[0024] The present invention also provides an application of hibiscus extract in cosmetics, which have the effect of highly effective and long-lasting oil control.

[0025] As an example of an implementable approach, the roselle extract is as described above.

[0026] This invention employs a semi-biomimetic extraction process of "alkali extraction followed by acid extraction." In the weakly alkaline stage (pH 7.5-9.5), the intestinal environment is simulated, allowing highly polar active ingredients such as polysaccharides, proteins, and flavonoids to fully dissolve while simultaneously disrupting plant cell walls. Subsequently, in the acidic stage (pH 2-4), the gastric environment is simulated, further extracting acidic components such as organic acids and anthocyanins. This alternating acid-alkali extraction process can simultaneously cover active substances of different polarities in roselle, effectively increasing the total extraction rate. Furthermore, the final extract, after decolorization by activated carbon, is nearly neutral, significantly reducing the risk of discoloration or degradation due to pH fluctuations. This overcomes the poor stability of products obtained from traditional alkaline extraction or single acid / alkali extraction.

[0027] Compared with existing technologies, the preparation and extraction process provided by this invention uses water as the extraction medium throughout the entire process, without the need for organic solvents such as ethanol or acetone, which meets the requirements of green chemistry. Furthermore, by controlling the extraction temperature at 35-42℃ and the stirring speed at 400-800rpm, heat-sensitive components are protected and industrial scale-up is easily achieved. The resulting roselle extract can significantly inhibit sebum secretion from SZ95 sebaceous gland cells at a dosage of 0.25-0.5wt%, and its ability to promote the dispersion of keratin plugs has been confirmed by an artificial keratin plug model, ultimately achieving efficient oil control.

[0028] Beneficial effects (i) This invention utilizes a semi-bionic extraction process, employing alkali extraction followed by acid extraction, which significantly improves the stability of roselle extract. Experiments show that the extract did not change color or deteriorate under strong light irradiation, while extracts obtained by traditional ethanol extraction or enzymatic hydrolysis methods showed obvious color changes after light exposure. Therefore, the roselle extract obtained by this invention has higher stability.

[0029] (ii) The roselle extract obtained in this application is rich in polyphenols and organic acids. According to the linoleic acid-induced sebaceous gland cell model test, the extract at a concentration of 0.5 wt% can reduce sebum secretion by 25.49%, which is comparable to the effect of isotretinoin. Furthermore, human trials show that continuous use for 14 days can reduce skin sebum content by 23.8%, demonstrating excellent oil control effect.

[0030] (III) The optimized process of the roselle extract of the present invention can achieve an extraction yield of up to 9%, which is much higher than the traditional ethanol extraction method or enzymatic hydrolysis method. At the same time, the content of polyphenols and organic acids is significantly increased, and the active ingredients are fully preserved.

[0031] (iv) The process provided in this application uses pure water extraction throughout, avoiding the use of organic solvents such as ethanol and ethyl acetate. The wastewater treatment after activated carbon decolorization is simple and meets environmental protection requirements. At the same time, the temperature is controlled at 35-42℃ during the process provided in this application, resulting in low energy consumption and suitability for industrial production.

[0032] (v) The roselle extract obtained by this invention is a white or light yellow powder with no irritating odor. It can be stably added to products such as serums and lotions, and has multiple effects such as oil control, acne removal and potential whitening, to meet diverse skin care needs. Attached Figure Description

[0033] Figure 1 This is a schematic diagram illustrating the stability of the roselle extract in Example 1, where the left side shows the appearance of the sample before light exposure and the right side shows the appearance of the sample after light exposure.

[0034] Figure 2 This is a schematic diagram illustrating the stability of the roselle extract in Comparative Example 1. The left side shows the appearance of the sample before light exposure, and the right side shows the appearance of the sample after light exposure.

[0035] Figure 3 This is a schematic diagram showing the experimental results of the effect of hibiscus extract on LA-induced lipid peroxidation in SZ95 cells.

[0036] Figure 4The diagram illustrates how hibiscus extract promotes the shedding of artificial keratin plugs. Sample group A (pure water on the left, hibiscus extract control on the right) shows the keratin shedding at 0 hours after sample addition; sample group B (pure water on the left, hibiscus extract control on the right) shows the keratin shedding at 24 hours after sample addition; and sample group C (pure water on the left, hibiscus extract control on the right) shows the keratin shedding after 24 hours after sample addition with gentle shaking of the bottle.

[0037] Figure 5 This is a schematic diagram illustrating the effect of hibiscus extract on inhibiting lipid microfilaments on days 1, 2, and 3.

[0038] Figure 6 This diagram illustrates the effect of hibiscus extract on reducing skin oil content on days 7 and 14. Detailed Implementation

[0039] Example 1 This example provides a method for preparing a roselle extract with stable oil-controlling effects, specifically as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through a 40-mesh sieve to obtain 500 g of roselle powder of uniform size. S2, roselle powder and 2500 g of pure water are mixed, heated to 35 ℃ and stirred evenly; S3. Add NaOH aqueous solution to adjust the pH of the solution to 7.5; S4. Start stirring, stabilize the temperature of the liquid at 35 ℃, and perform alkali extraction at 400 rpm for 2 hours; S5. Filtration, collecting the filter residue and the first extract; S6. Add 2500 g of pure water to the filter residue, heat to 35 ℃ and stir evenly; S7. Add hydrochloric acid aqueous solution to adjust the pH of the solution to 2; S8. Start stirring, stabilize the temperature of the liquid at 35 ℃, and perform acid extraction at 400 rpm for 1 h; S9. Filter and collect the second extract; S10. Combine the first and second extracts to form a total of 5500 g of liquid, add 5.5 g of activated carbon, and stir at room temperature (25°C) for 0.5 h. S11. Filter and collect the decolorized and impurity-removed solution; S12. Concentrate the decolorizing and impurity-removing solution to 500 g, set the inlet air temperature to 180 ℃ and the outlet air temperature to 90 ℃ for spray drying, to obtain 35 g of roselle extract. The extract is a pale yellow powder with a characteristic odor.

[0040] The second aspect of this example provides a roselle extract prepared by the above-described preparation method.

[0041] When the roselle extract is used in cosmetics, the cosmetics have a highly effective and long-lasting stable oil-controlling effect.

[0042] Example 2 This example provides a method for preparing a roselle extract with stable oil-controlling effects, specifically as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through an 80-mesh sieve to obtain 500 g of roselle powder of uniform size. S2, roselle powder and 5000 g pure water are mixed, heated to 40 ℃ and stirred evenly; S3. Add Ca(OH)2 aqueous solution to adjust the pH of the solution to 9.5; S4. Start stirring, stabilize the temperature of the liquid at 40 ℃, and perform alkali extraction at 800 rpm for 4 hours; S5. Filtration, collecting the filter residue and the first extract; S6. Add 5000 g of pure water to the filter residue, heat to 42 ℃ and stir evenly; S7. Add citric acid aqueous solution to adjust the pH of the solution to 4; S8. Start stirring, stabilize the liquid temperature at 42 ℃, and perform acid extraction at 800 rpm for 3 hours; S9. Filter and collect the second extract; S10. Combine the first and second extracts to form a total of 10200 g of liquid, and add 27.5 g of activated carbon. Stir at room temperature (25°C) for 2 h. S11. Filter and collect the decolorized and impurity-removed solution; S12. Concentrate the decolorizing and impurity-removing solution to 400 g, set the inlet air temperature to 180 ℃ and the outlet air temperature to 90 ℃ for spray drying, to obtain 37 g of roselle extract. The extract is an off-white powder with a characteristic odor.

[0043] Example 3 This example provides a method for preparing a roselle extract with stable oil-controlling effects, specifically as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through an 80-mesh sieve to obtain 500 g of roselle powder of uniform size. S2, roselle powder and 4000 g pure water are mixed, heated to 37 ℃ and stirred evenly; S3. Add NaOH aqueous solution to adjust the pH of the solution to 8.2; S4. Start stirring, stabilize the temperature of the liquid at 37 ℃, and perform alkali extraction at 600 rpm for 3 hours; S5. Filtration, collecting the filter residue and the first extract; S6. Add 4000 g of pure water to the filter residue, heat to 40 ℃ and stir evenly; S7. Add hydrochloric acid aqueous solution to adjust the pH of the solution to 3; S8. Start stirring, stabilize the temperature of the liquid at 40 ℃, and perform acid extraction at 600 rpm for 2 hours; S9. Filter and collect the second extract; S10. Combine the first and second extracts to form a total of 8200g of liquid, add 11g of activated carbon, and stir at room temperature (25℃) for 1 hour. S11. Filter and collect the decolorized and impurity-removed solution; S12. Concentrate the decolorizing and impurity-removing solution to 600 g, set the inlet air temperature to 180 ℃ and the outlet air temperature to 90 ℃ for spray drying, to obtain 45 g of roselle extract. The extract is an off-white powder with a characteristic odor.

[0044] Example 4 This example provides a method for preparing a roselle extract with stable oil-controlling effects, specifically as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through a 60-mesh sieve to obtain 500 g of roselle powder of uniform size. S2, roselle powder and 4000 g pure water are mixed, heated to 37 ℃ and stirred evenly; S3. Add NaOH aqueous solution to adjust the pH of the solution to 8.2; S4. Start stirring, stabilize the temperature of the liquid at 37 ℃, and perform alkali extraction at 600 rpm for 3 hours; S5. Filtration, collecting the filter residue and the first extract; S6. Add 4000 g of pure water to the filter residue, heat to 40 ℃ and stir evenly; S7. Add hydrochloric acid aqueous solution to adjust the pH of the solution to 3; S8. Start stirring, stabilize the temperature of the liquid at 40 ℃, and perform acid extraction at 600 rpm for 2 hours; S9. Filter and collect the second extract; S10. Combine the first and second extracts to form a total of 8200 g of liquid, add 11 g of activated carbon, and stir at room temperature (25°C) for 1 h. S11. Filter and collect the decolorized and impurity-removed solution; S12. Concentrate the decolorized and impurity-removing solution to 600 g, set the inlet air temperature to 180 ℃ and the outlet air temperature to 90 ℃ for spray drying, to obtain 44 g of roselle extract. The extract is an off-white powder with a characteristic odor.

[0045] Example 5 This example provides a method for preparing a roselle extract with stable oil-controlling effects, specifically as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through a 60-mesh sieve to obtain 500 g of roselle powder of uniform size. S2, roselle powder and 4000 g pure water are mixed, heated to 39 ℃ and stirred evenly; S3. Add NaOH aqueous solution to adjust the pH of the solution to 9.4; S4. Start stirring, stabilize the temperature of the liquid at 37 ℃, and perform alkali extraction at 600 rpm for 3 hours; S5. Filtration, collecting the filter residue and the first extract; S6. Add 4000 g of pure water to the filter residue, heat to 40 ℃ and stir evenly; S7. Add hydrochloric acid aqueous solution to adjust the pH of the solution to 3; S8. Start stirring, stabilize the temperature of the liquid at 40 ℃, and perform acid extraction at 600 rpm for 2 hours; S9. Filter and collect the second extract; S10. Combine the first and second extracts to form a total of 8200 g of liquid, add 11 g of activated carbon, and stir at room temperature (25°C) for 1 h. S11. Filter and collect the decolorized and impurity-removed solution; S12. Concentrate the decolorizing and impurity-removing solution to 600 g, set the inlet air temperature to 180 ℃ and the outlet air temperature to 90 ℃ for spray drying, to obtain 38 g of roselle extract. The extract is an off-white powder with a characteristic odor.

[0046] Example 6 This example provides a method for preparing a roselle extract with stable oil-controlling effects, specifically as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through a 40-mesh sieve to obtain 500 g of roselle powder of uniform size. S2, roselle powder and 3500 g pure water are mixed, heated to 37 ℃ and stirred evenly; S3. Add NaOH aqueous solution to adjust the pH of the solution to 7.2; S4. Start stirring, stabilize the temperature of the liquid at 35 ℃, and perform alkali extraction at 400 rpm for 2 hours; S5. Filtration, collecting the filter residue and the first extract; S6. Add 3500 g of pure water to the filter residue, heat to 35 ℃ and stir evenly; S7. Add hydrochloric acid aqueous solution to adjust the pH of the solution to 2.5; S8. Start stirring, stabilize the temperature of the liquid at 35 ℃, and perform acid extraction at 400 rpm for 1 h; S9. Filter and collect the second extract; S10. Combine the first and second extracts to form a total of 7100 g of liquid, add 5.5 g of activated carbon, and stir at room temperature (25°C) for 0.5 h. S11. Filter and collect the decolorized and impurity-removed solution; S12. Concentrate the decolorizing and impurity-removing solution to 500 g, set the inlet air temperature to 180 ℃ and the outlet air temperature to 90 ℃ for spray drying, and obtain 32 g of roselle extract. The extract is a light yellow powder with a characteristic odor.

[0047] Example 7 This example provides a method for preparing a roselle extract with stable oil-controlling effects, specifically as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through a 40-mesh sieve to obtain 500 g of roselle powder of uniform size. S2, roselle powder and 2500 g of pure water are mixed, heated to 35 ℃ and stirred evenly; S3. Add NaOH aqueous solution to adjust the pH of the solution to 7.9; S4. Start stirring, stabilize the temperature of the liquid at 35 ℃, and perform alkali extraction at 400 rpm for 2 hours; S5. Filtration, collecting the filter residue and the first extract; S6. Add 2500 g of pure water to the filter residue, heat to 35 ℃ and stir evenly; S7. Add hydrochloric acid aqueous solution to adjust the pH of the solution to 2; S8. Start stirring, stabilize the temperature of the liquid at 35 ℃, and perform acid extraction at 400 rpm for 1 h; S9. Filter and collect the second extract; S10. Combine the first and second extracts to form a total of 5500 g of liquid, add 5.5 g of activated carbon, and stir at room temperature (25°C) for 0.5 h. S11. Filter and collect the decolorized and impurity-removed solution; S12. Concentrate the decolorizing and impurity-removing solution to 500 g, set the inlet air temperature to 180 ℃ and the outlet air temperature to 90 ℃ for spray drying, to obtain 34 g of roselle extract. The extract is a pale yellow powder with a characteristic odor.

[0048] Example 8 This example provides a method for preparing a roselle extract with stable oil-controlling effects, specifically as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through a 60-mesh sieve to obtain 500 g of roselle powder of uniform size. S2, roselle powder and 3500 g pure water are mixed, heated to 39 ℃ and stirred evenly; S3. Add NaOH aqueous solution to adjust the pH of the solution to 8.5; S4. Start stirring, stabilize the temperature of the liquid at 37 ℃, and perform alkali extraction at 600 rpm for 3 hours; S5. Filtration, collecting the filter residue and the first extract; S6. Add 3500 g of pure water to the filter residue, heat to 40 ℃ and stir evenly; S7. Add hydrochloric acid aqueous solution to adjust the pH of the solution to 3; S8. Start stirring, stabilize the temperature of the liquid at 40 ℃, and perform acid extraction at 600 rpm for 2 hours; S9. Filter and collect the second extract; S10. Combine the first and second extracts to form a total of 7200 g of liquid, add 36 g of activated carbon, and stir at room temperature (25°C) for 1 h. S11. Filter and collect the decolorized and impurity-removed solution; S12. Concentrate the decolorizing and impurity-removing solution to 600 g, set the inlet air temperature to 180 ℃ and the outlet air temperature to 90 ℃ for spray drying, to obtain 40 g of roselle extract. The extract is an off-white powder with a characteristic odor.

[0049] Example 9 This example provides a method for preparing a roselle extract with stable oil-controlling effects, specifically as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through a 60-mesh sieve to obtain 500 g of roselle powder of uniform size. S2, roselle powder and 3800 g of pure water are mixed, heated to 37 ℃ and stirred evenly; S3. Add NaOH aqueous solution to adjust the pH of the solution to 8.8; S4. Start stirring, stabilize the temperature of the liquid at 37 ℃, and perform alkali extraction at 600 rpm for 3 hours; S5. Filtration, collecting the filter residue and the first extract; S6. Add 3800 g of pure water to the filter residue, heat to 40 ℃ and stir evenly; S7. Add hydrochloric acid aqueous solution to adjust the pH of the solution to 3; S8. Start stirring, stabilize the temperature of the liquid at 40 ℃, and perform acid extraction at 600 rpm for 2 hours; S9. Filter and collect the second extract; S10. Combine the first and second extracts to form a total of 7800 g of liquid, add 35 g of activated carbon, and stir at room temperature (25°C) for 1 h. S11. Filter and collect the decolorized and impurity-removed solution; S12. Concentrate the decolorizing and impurity-removing solution to 600 g, set the inlet air temperature to 180 ℃ and the outlet air temperature to 90 ℃ for spray drying, to obtain 41 g of roselle extract. The extract is an off-white powder with a characteristic odor.

[0050] Example 10 This example provides a method for preparing a roselle extract with stable oil-controlling effects, specifically as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through a 40-mesh sieve to obtain 500 g of roselle powder of uniform size. S2, roselle powder and 2800 g of pure water are mixed, heated to 38 ℃ and stirred evenly; S3. Add NaOH aqueous solution to adjust the pH of the solution to 8.0; S4. Start stirring, stabilize the temperature of the liquid at 35 ℃, and perform alkali extraction at 400 rpm for 2 hours; S5. Filtration, collecting the filter residue and the first extract; S6. Add 2800 g of pure water to the filter residue, heat to 38 ℃ and stir evenly; S7. Add hydrochloric acid solution to adjust the pH of the solution to 2.2; S8. Start stirring, stabilize the liquid temperature at 35 ℃, and perform acid extraction at 400 rpm for 2 hours; S9. Filter and collect the second extract; S10. Combine the first and second extracts to form a total of 5700 g of liquid, add 5.7 g of activated carbon, and stir at room temperature (25°C) for 0.5 h. S11. Filter and collect the decolorized and impurity-removed solution; S12. Concentrate the decolorizing and impurity-removing solution to 500 g, set the inlet air temperature to 180 ℃ and the outlet air temperature to 90 ℃ for spray drying, to obtain 30 g of roselle extract. The extract is a pale yellow powder with a characteristic odor.

[0051] Comparative Example 1 This example provides a method for preparing hibiscus extract. Referring to the technical solution in CN113208960B, the specific steps are as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through a 40-mesh sieve to obtain 500 g of roselle powder of uniform size. S2. Add 10,000 g of pure water to the roselle powder, break it up under high shear to obtain a slurry, add 15 g of cellulase and 15 g of pectinase, heat to 50℃, enzymatically hydrolyze for 4 h, filter, then heat to 80℃ and sterilize for 1 h to obtain the extract. S3. Inoculate the extract with Lactobacillus (Gray Algae Bio, HZB132885) and ferment at 38°C for two weeks; S4. Sterilize and filter the fermentation broth to obtain roselle fermentation filtrate; S5. Add 5g of activated carbon to the fermented hibiscus filtrate, stir at room temperature (about 25℃) for 0.5h, filter, take the filtrate, freeze dry to obtain 18g of fermented hibiscus powder. The extract is a red powder with a characteristic odor.

[0052] Comparative Example 2 This example provides a method for preparing hibiscus extract. Referring to the technical solution in CN111202779B, the specific steps are as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through a 60-mesh sieve to obtain 500 g of roselle powder of uniform size. S2. Add 10,000 g of powder to an 85 wt% ethanol aqueous solution, sonicate for 30 min, then heat to 85 ℃ and stir to extract for 4 h; S3. Filter to obtain the extract; add 5g of activated carbon, stir at room temperature (about 25℃) for 0.5h, filter, and collect the filtrate; S4. The filtrate is concentrated under reduced pressure until no ethanol is present. After filtration, a clear liquid is obtained. The inlet air temperature is set to 180 ℃ and the outlet air temperature is set to 90 ℃ for spray drying to obtain 16 g of roselle extract. The extract is a red powder with a characteristic odor.

[0053] Comparative Example 3 This example provides a method for preparing a roselle extract with stable oil-controlling effects, specifically as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through a 60-mesh sieve to obtain 500 g of roselle powder of uniform size. S2, roselle powder and 4000 g pure water are mixed, heated to 35 ℃ and stirred evenly; S3. Add NaOH aqueous solution to adjust the pH of the solution to 10.0; S4. Start stirring, stabilize the temperature of the liquid at 35 ℃, and perform alkali extraction at 600 rpm for 3 hours; S5. Filtration, collecting the filter residue and the first extract; S6. Add 4000 g of pure water to the filter residue, heat to 40 ℃ and stir evenly; S7. Add hydrochloric acid solution to adjust the pH of the solution to 5.0; S8. Start stirring, stabilize the temperature of the liquid at 40 ℃, and perform acid extraction at 600 rpm for 2 hours; S9. Filter and collect the second extract; S10. Combine the first and second extracts to form a total of 8200 g of liquid, add 11 g of activated carbon, and stir at room temperature (25°C) for 1 h. S11. Filter and collect the decolorized and impurity-removed solution; S12. Concentrate the decolorizing and impurity-removing solution to 600 g, set the inlet air temperature to 180 ℃ and the outlet air temperature to 90 ℃ for spray drying, to obtain 24 g of roselle extract. The extract is a pale yellow powder with a characteristic odor.

[0054] Comparative Example 4 This example provides a method for preparing a roselle extract with stable oil-controlling effects, specifically as follows: S1. Take dried roselle calyxes, remove impurities such as stones and wood chips, crush and pass through a 60-mesh sieve to obtain 500 g of roselle powder of uniform size. S2, roselle powder and 4000 g pure water are mixed, heated to 35 ℃ and stirred evenly; S3. Add NaOH aqueous solution to adjust the pH of the solution to 8.5; S4. Start stirring, stabilize the temperature of the liquid at 35 ℃, and perform alkali extraction at 600 rpm for 3 hours; S5. Filtration, collecting the filter residue and the first extract; S6. Add 4000 g of pure water to the filter residue, heat to 40 ℃ and stir evenly; S7. Add hydrochloric acid aqueous solution to adjust the pH of the solution to 1.0; S8. Start stirring, stabilize the temperature of the liquid at 40 ℃, and perform acid extraction at 600 rpm for 2 hours; S9. Filter and collect the second extract; S10. Combine the first and second extracts to form a total of 8200 g of liquid, add 11 g of activated carbon, and stir at room temperature (25°C) for 1 h. S11. Filter and collect the decolorized and impurity-removed solution; S12. Concentrate the decolorizing and impurity-removing solution to 600 g, set the inlet air temperature to 180 ℃ and the outlet air temperature to 90 ℃ for spray drying, to obtain 20 g of roselle extract. The extract is a pale yellow powder with a characteristic odor.

[0055] Performance testing 1. Physicochemical properties and yield testing The yield, polyphenol content, and organic acid content of the roselle extract obtained in Test Examples 1-10 and Comparative Examples 1-4 are detailed in Table 1.

[0056] Method for measuring polyphenol content: Refer to T / AHFIA 005-2018 Spectrophotometric method for determination of total polyphenol content in plant extracts and their products; Method for measuring organic acid content: Refer to GB 12456-2021 National Food Safety Standard - Determination of total acid in food.

[0057] Table 1

[0058] As can be seen from the experimental results in Table 1, the semi-biomimetic extraction method of first alkali extraction and then acid extraction in this invention can improve the yield, polyphenol content, organic acid content, and property stability of roselle extract, and is superior to traditional enzymatic extraction and alkali extraction. Through comparative analysis, the optimal implementation scheme was found to be the extraction conditions of Example 3, while Comparative Example 1 showed relatively higher yield and characteristic index content. Therefore, Example 3 and Comparative Example 1 were selected for subsequent efficacy and performance comparison tests.

[0059] 2. Stability performance test The stability of the roselle extract prepared in Example 3 and Comparative Example 1 was investigated. To simulate its use in the formulation, the roselle extract was dissolved into a liquid of a certain concentration for testing. The specific preparation method was as follows: 5g of roselle extract powder was taken, 45g of pure water and 50g of 1,3-propanediol were added, and the mixture was stirred at room temperature (about 25°C) until completely dissolved. The mixture was then sterilized by heating in an 80°C water bath for 30 minutes and dispensed for stability testing.

[0060] Stability results showed that under strong light irradiation of 4500 Lux, the sample prepared in Comparative Example 1 showed a significant color change after 4 hours, with the liquid color changing from red to pale yellow. Specifically, as shown below... Figure 2 As shown. However, the roselle extract prepared in Example 3 showed no significant change, as... Figure 1 As shown. Therefore, the roselle extract prepared by the method described in this invention has good stability and can be more widely used in cosmetic formulations.

[0061] 3. Acne-removing and oil-controlling efficacy performance test The efficacy of the hibiscus extract liquid prepared by the method described in this invention was tested after stability testing to demonstrate that the hibiscus extract prepared by the method described in this invention has good oil-controlling effects.

[0062] Specifically, this experiment used a linoleic acid (LA)-induced SZ95 sebaceous gland cell model and measured sebum secretion to evaluate the oil-controlling effect of hibiscus extract. Figure 3 The experimental results in Table 2 (Effect of Roselle Extract Extracted in Example 3 on Lipid Content in LA-Induced SZ95 Cells) show that, compared with the induction group (NC) and the 1 μM isotretinoin treatment group (PC), treatment with 0.25wt% and 0.5wt% Roselle extract can effectively inhibit lipid secretion.

[0063] Table 2

[0064] 4. Corner plug detachment test Lipid filaments / blackheads are plug-like substances composed of sebum (a mixture of products secreted and excreted by sebaceous glands, containing various lipids, mainly saturated and unsaturated free fatty acids, glycerides, etc.), cell debris, and bacteria. The formation process is as follows: shed keratinocytes block hair follicles, and sebum secreted by the sebaceous glands mixes with them, solidifies, hardens, and accumulates in the pore to form a keratin plug. The exposed portion of the keratin plug oxidizes upon contact with air and turns black.

[0065] This test case simulates the preparation of an artificial keratin plug and tests the effect of roselle extract. For example... Figure 4 As shown, after standing for 24 hours, compared with the pure water group, the artificial keratin plugs in the 5wt% hibiscus extract group were larger. When the glass tube was gently shaken, the artificial keratin plugs in the 5wt% hibiscus extract group were more easily peeled and dispersed from the bottom. The results indicate that the hibiscus extract group can further achieve the effects of cleaning and efficient oil control by promoting the removal of keratin plugs.

[0066] 5. Lipid microfilament inhibition test This test case mainly provides an application solution and conducts an oil-control efficacy test on the human body. The ingredients of the serum, by weight percentage, include: 0.05% xanthan gum, 2% glyceryl polyether-26, 0.05% disodium EDTA, 0.5% acryloyl dimethyl taurate / VP copolymer, 3% glycerin, 0.5% p-hydroxyacetophenone, 0.5% 1,2-hexanediol, 1% roselle extract, and 92.4% water.

[0067] The results of the lipid microfilament inhibition test are as follows Figure 5-6 As shown in Tables 3-4, compared with the blank group, the number of lipid microfilaments decreased significantly after the subjects used the product for 1, 2 and 3 days, and the skin oil content decreased significantly after 7 and 14 days.

[0068] Table 3

[0069] Table 4

[0070] from Figure 5-6, Figure 3-4 The experimental results show that when the roselle extract provided by this invention is used as a raw material for cosmetics, it can significantly reduce the skin's oil content, inhibit the formation of lipid filaments, reduce the number of lipid filaments, and achieve efficient and long-lasting oil control.

Claims

1. A method for preparing hibiscus extract, characterized in that, The preparation method of hibiscus extract includes the following steps: Remove impurities from dried roselle calyxes, sift, and obtain roselle powder; Mix roselle powder and water, heat, stir well, then add alkaline solution to adjust the pH of the system to 7.5-9.5; Alkaline extraction for 2-4 hours, followed by filtration, collection of filter residue and first extract; Mix the filter residue with water, heat it, stir it evenly, and then add acid solution to adjust the pH of the system to 2-4. Acid extract for 1-3 hours, filter, and collect the second extract; The first and second extracts were combined, concentrated, and dried to obtain the roselle extract.

2. The method for preparing hibiscus extract according to claim 1, characterized in that, The sieve mesh size is 20-100 mesh.

3. The method for preparing hibiscus extract according to claim 1, characterized in that, The mass ratio of the roselle powder to water is 1:(5-10).

4. The method for preparing hibiscus extract according to claim 1, characterized in that, The roselle powder and water are mixed and then heated to a temperature of 35-40℃.

5. The method for preparing hibiscus extract according to any one of claims 1-4, characterized in that, The alkaline solution is an aqueous solution of NaOH, KOH, or Ca(OH)2; and / or, the acid solution is an aqueous solution of hydrochloric acid or citric acid.

6. The method for preparing hibiscus extract according to claim 1, characterized in that, The stirring rate for the alkali extraction is 400-800 rpm.

7. The method for preparing hibiscus extract according to claim 1, characterized in that, The filter residue and water are mixed and then heated to a temperature of 35-42℃.

8. The method for preparing hibiscus extract according to claim 1, characterized in that, After combining the first and second extracts, an adsorbent is added, and the mixture is stirred for 0.5-2 hours. The mixture is then filtered, and the decolorized and impurity-removed liquid is collected. The liquid is then concentrated and dried to obtain the roselle extract.

9. A roselle extract, characterized in that, The roselle extract is prepared by the preparation method according to any one of claims 1-8; Furthermore, the polyphenol content in the roselle extract is not less than 8%; and / or, the organic acid content in the roselle extract is not less than 15%.

10. An application of the hibiscus extract as described in claim 9 in cosmetics, characterized in that, The cosmetic product has a highly effective and long-lasting oil-controlling effect.

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