Pomegranate peel extract as well as preparation method and application thereof

Abstract

The invention discloses a pomegranate rind extract and a preparation method and application thereof, the pomegranate rind extract is prepared by the following method: adding water and compound enzyme into pomegranate rind powder for enzymolysis to obtain pomegranate rind enzymatic hydrolysate; adding an ethanol solution into the pomegranate peel enzymatic hydrolysate, heating and extracting, filtering, and carrying out rotary evaporation to obtain an extract concentrated solution; adding the extract concentrated solution into the sodium alginate solution to obtain a mixed solution, spraying the mixed solution into the chitosan composite solution, standing, washing, and performing vacuum freeze drying to obtain the pomegranate peel extract. Pomegranate rind is selected as a raw material, tannin and cell wall structures are effectively destroyed through complex enzyme pretreatment, wrapped active ingredients are fully released, an ethanol solution is added for extraction, it is ensured that most target ingredients are dissolved, and then an extracting solution is concentrated to improve the concentration of the active ingredients; active ingredients in the extracting solution are wrapped by using a sharp hole coagulating bath method, so that the solubility and the stability of active matters are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of cosmetics, and particularly relates to a pomegranate peel extract, a preparation method thereof, and an application thereof. Background Art

[0002] With the increasing attention of consumers to the efficacy and safety of natural skin care products, plant-derived active substances with antioxidant and whitening activities have become a research hotspot in the cosmetics field. Pomegranate peel is rich in various bioactive components such as polyphenols, flavonoids, and tannins, which endow it with significant antioxidant and whitening effects. Therefore, pomegranate peel extract has broad application prospects in the development of natural cosmetic raw materials with whitening and anti-aging functions.

[0003] However, despite the rich content of these high-value active components in pomegranate peel, the current extraction methods have certain limitations. Currently, the extraction of active components from pomegranate peel mainly relies on organic solvent dissolution and extraction. Although this can extract most of the free and some intracellular active components in pomegranate peel, a considerable part exists in the form of tannins, and some are wrapped in cells by cell walls and cannot come into contact with the solvent for extraction, ultimately reducing the extraction efficiency.

[0004] In recent years, some methods have been used to pretreat pomegranate peel to increase the extraction efficiency, such as ultrasonic-assisted extraction method, microwave-assisted extraction method, etc. Although these methods can, to a certain extent, destroy the tannin structure and break the cell wall to release intracellular active substances, the equipment investment is high and the effect is not obvious enough; the acidolysis extraction method, which first treats the raw material with acid solution and then extracts and finally alkalizes and purifies, greatly improves the extraction efficiency and the process is simple, but a large amount of strong acid and strong base are used in the extraction process, and the equipment's acid and alkali resistance requirements are also high, and the active components may degrade under high temperature or strong acid / strong base conditions; the microbial fermentation method, which uses bioenzymes secreted by microorganisms such as Aspergillus niger to degrade components such as cellulose and pectin in pomegranate peel to promote the release of active substances, but the fermentation time is long and the mycelia produced by fermentation increase the extraction difficulty. In addition, the active components in pomegranate peel extract are easily degraded under the conditions of light, high temperature, and oxygen, resulting in a decrease in their biological activity. At the same time, the water solubility of these components is poor and it is difficult to be uniformly dispersed in cosmetic formulations, further limiting their application effects. Therefore, developing a method that can efficiently extract pomegranate peel active components and improve their stability and water solubility has important research significance. Summary of the Invention

[0005] In view of the above-mentioned prior art, the object of the present invention is to provide a pomegranate peel extract, its preparation method and application. The present invention selects pomegranate peel as the raw material, which is washed, dried, pulverized, then added with water and a composite enzyme for enzymatic hydrolysis, and then an ethanol solution is added for extraction to obtain a pomegranate peel extract solution. Subsequently, it is concentrated to obtain a concentrated solution. Finally, the active ingredients in the pomegranate peel extract solution are encapsulated by the sharp orifice coagulation bath method to obtain the pomegranate peel extract. The pomegranate peel extract prepared by the present invention is rich in phenolic and flavonoid substances, with contents up to 56.8% and 9.07% respectively. The scavenging rate of DPPH free radicals can reach 71.08%, and the inhibition rate of tyrosinase can reach 55.43%. When it is applied to skin care products, it has an obvious whitening effect, and its state is stable and it is not easy to change color and precipitate.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect of the present invention, a pomegranate peel extract is provided, which is prepared by the following method:

[0008] (1) Add pomegranate peel powder to water and a composite enzyme for enzymatic hydrolysis to obtain a pomegranate peel enzymatic hydrolysate;

[0009] (2) Add an ethanol solution with a volume fraction of 90-99% to the pomegranate peel enzymatic hydrolysate, heat for extraction, filter and rotary evaporate to obtain an extract concentrated solution;

[0010] (3) Add the extract concentrated solution to a sodium alginate solution to obtain a mixed solution. Spray the mixed solution into a chitosan composite solution, let it stand, wash, and vacuum freeze-dry to obtain the pomegranate peel extract.

[0011] Preferably, in step (1), the specific steps of enzymatic hydrolysis are as follows:

[0012] Mix pomegranate peel powder and water at a mass ratio of 1:(8-15), add citric acid to adjust the pH to 4.5-5.5, then add a composite enzyme accounting for 0.01%-0.03% of the weight of the pomegranate peel powder, heat to 50-60°C, stir for 5-8 h, raise the temperature to 85-95°C and maintain for 3-7 min, and then cool down to obtain the pomegranate peel enzymatic hydrolysate.

[0013] Preferably, the composite enzyme is composed of pectinase, β-glucosidase, tannase and papain mixed in a mass ratio of (1-3):(0.5-1.5):(2-4):(0.5-1.5).

[0014] Preferably, in step (2), the mass ratio of the pomegranate peel enzymatic hydrolysate to the ethanol solution is 1:(1-2).

[0015] Preferably, in step (2), the extraction temperature is 40-60°C and the extraction time is 0.5-2 h.

[0016] Preferably, in step (2), the rotary evaporation temperature is 40 - 60°C, and the rotary evaporation is stopped when the volume is reduced to 4 - 6% of that before rotary evaporation.

[0017] Preferably, in step (3), the preparation method of the sodium alginate solution is as follows: Sodium alginate is added to water to make its mass fraction 2 - 4%, heated to 50 - 70°C, stirred, and cooled to obtain the sodium alginate solution.

[0018] Preferably, in step (3), the mass ratio of sodium alginate to the extract concentrate is (2 - 4):1.

[0019] Preferably, in step (3), the mixture is sprayed into the chitosan composite solution with a spray gun having a pore size of 0.6 - 1.0 mm. The chitosan composite solution is an aqueous solution containing 0.5% - 1% chitosan and 5 - 8% CaCl2 by mass fraction, and the standing time is 20 - 40 min.

[0020] Preferably, in step (3), the vacuum freeze - drying process is as follows: During the pre - freezing process, the temperature is - 50 to - 40°C and the treatment time is 1 - 3 h; during the first sublimation process, the temperature is - 5 - 5°C, the vacuum degree is 5 - 15 Pa, and the treatment time is 3 - 5 h; during the second sublimation process, the temperature is - 5 - 5°C, the vacuum degree is 5 - 15 Pa, and the treatment time is 3 - 5 h; during the third sublimation process, the temperature is 10 - 20°C, the vacuum degree is 5 - 15 Pa, and the treatment time is 0.5 - 1.5 h.

[0021] In the second aspect of the present invention, there is provided the use of the above - mentioned pomegranate peel extract in the preparation of a product for whitening or antioxidant.

[0022] Advantages of the present invention:

[0023] 1. The present invention selects pomegranate peel as the raw material. First, through composite enzyme pretreatment, the tannin and cell wall structure are effectively destroyed, and the encapsulated active ingredients are fully released. Then, an ethanol solution is added for extraction to ensure that most of the target components are dissolved. Next, the extract is concentrated to increase the concentration of the active ingredients. Finally, the active ingredients in the extract are encapsulated by the coacervation phase separation method, which significantly improves the solubility and stability of the active substances, thus ensuring the uniform dispersion and long - term activity of the product in the cosmetic formula. The whole process is not only simple and efficient, but also greatly enhances the quality and application prospect of the final product.

[0024] 2. The scavenging rate of the pomegranate peel extract prepared by the present invention on DPPH free radicals can reach 71.08%, and the inhibition rate on tyrosinase can reach 55.43%. Therefore, it can be seen that the pomegranate peel extract prepared by the present invention has good antioxidant and whitening effects. Specific embodiments

[0025] It should be noted that the following detailed description is illustrative and aims to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0026] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific embodiments.

[0027] The test materials used in the embodiments of the present invention are all conventional test materials in the art and can be obtained through commercial channels.

[0028] The pectinase used in the present invention is purchased from Yiwei Bioengineering Co., Ltd., and the enzyme activity is 10000 U / g;

[0029] The β-glucosidase used is purchased from Yiwei Bioengineering Co., Ltd., and the enzyme activity is 50000 U / g;

[0030] The tannase used is purchased from Henan Shengfa Biotechnology Co., Ltd., and the enzyme activity is 500 U / g;

[0031] The papain used is purchased from Nanning Pangbo Bioengineering Co., Ltd., and the enzyme activity is 10000 U / g.

[0032] Example 1: Preparation of pomegranate peel extract:

[0033] (1) Wash the pomegranate peel of Daqingpi, dry it at 50 °C to constant weight, then crush it, pass through a 40-mesh sieve to obtain pomegranate peel powder. Mix the pomegranate peel powder and water at a mass ratio of 1:12, stir evenly, add citric acid to adjust the pH of the mixture to 5.0, add a composite enzyme accounting for 0.02% of the weight of the pomegranate peel powder, heat to 55 °C, keep stirring for 6 h, raise the temperature to 90 °C and maintain for 5 min to terminate the enzymatic hydrolysis reaction, and cool to room temperature to obtain an enzymatic hydrolysate;

[0034] The composite enzyme is composed of pectinase, β-glucosidase, tannase and papain mixed in a mass ratio of 2:1:3:1;

[0035] (2) Add ethanol with a volume fraction of 95% that is 1.5 times the weight of the enzymatic hydrolysate to the enzymatic hydrolysate, mix evenly, heat the mixture to 50 °C, stir and extract for 1 h, then filter through a 400-mesh filter screen. The filtrate is rotary evaporated at 50 °C until the volume is reduced to 5% of that before rotary evaporation and then stop to obtain an extract concentrate;

[0036] (3) Prepare sodium alginate with a concentration of 3% and heat it to 60°C. Keep it warm and stir evenly. After it has fully swelled, take it out and cool it. Place it on a magnetic stirrer and add the extract concentrate while stirring according to the mass ratio of sodium alginate to extract concentrate of 3:1 to obtain a mixed solution. Spray the mixed solution into a chitosan composite solution containing 0.8% by mass of chitosan and 6% by mass of CaCl2 using a spray gun with a pore size of 0.8 mm. Let it stand for 30 min, filter, wash the water on the surface of the microcapsules with distilled water, and perform vacuum drying to obtain pomegranate peel extract;

[0037] The steps of vacuum drying are as follows: During the pre-freezing process, the temperature is -45°C and the treatment time is 2 h; during the first sublimation process, the temperature is 0°C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the second sublimation process, the temperature is 5°C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the third sublimation process, the temperature is 15°C, the vacuum degree is 10 Pa, and the treatment time is 1 h.

[0038] Example 2: Preparation of pomegranate peel extract

[0039] (1) Wash the pomegranate peel of Daqingpi clean, place it in an oven at 50°C and dry it to a constant weight, then crush it and pass it through a 40-mesh sieve to obtain pomegranate peel powder. Mix the pomegranate peel powder and water according to the mass ratio of 1:8 and stir evenly. Add citric acid to adjust the pH of the mixed solution to 5.0, add a composite enzyme accounting for 0.03% of the weight of the pomegranate peel powder, heat it to 60°C, keep it warm and stir for 8 h, raise the temperature to 90°C and maintain it for 5 min to terminate the enzymatic hydrolysis reaction, and cool it to room temperature to obtain an enzymatic hydrolysate;

[0040] The composite enzyme is composed of pectinase, β-glucosidase, tannase and papain mixed according to the mass ratio of 3:1.5:4:1.5;

[0041] (2) Add ethanol with a volume fraction of 95% twice the weight of the enzymatic hydrolysate to the enzymatic hydrolysate, mix evenly, heat the mixed solution to 50°C, stir and extract for 0.5 h, then filter it through a 400-mesh filter screen. The filtrate is rotary evaporated at 50°C until the volume is reduced to 5% of that before rotary evaporation and then stop to obtain an extract concentrate;

[0042] (3) Prepare sodium alginate with a concentration of 3% and heat it to 60°C. Keep it warm and stir evenly. After it has fully swelled, take it out and cool it. Place it on a magnetic stirrer and add the extract concentrate while stirring according to the mass ratio of sodium alginate to extract concentrate of 2:1 to obtain a mixed solution. Spray the mixed solution into a chitosan composite solution containing 0.8% by mass of chitosan and 6% by mass of CaCl2 using a spray gun with a pore size of 0.8 mm. Let it stand for 30 min, filter, wash the water on the surface of the microcapsules with distilled water, and perform vacuum drying to obtain pomegranate peel extract;

[0043] The steps of vacuum drying are as follows: during the pre-freezing process, the temperature is -45°C and the treatment time is 2 h; during the first sublimation process, the temperature is 0°C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the second sublimation process, the temperature is 5°C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the third sublimation process, the temperature is 15°C, the vacuum degree is 10 Pa, and the treatment time is 1 h.

[0044] Example 3: Preparation of pomegranate peel extract

[0045] (1) Clean the pomegranate peel of Daqingpi, dry it at 50°C until constant weight, then crush it, pass through a 40-mesh sieve to obtain pomegranate peel powder. Mix the pomegranate peel powder and water at a mass ratio of 1:15, stir evenly, add citric acid to adjust the pH of the mixed solution to 5.0, add a composite enzyme accounting for 0.01% of the weight of the pomegranate peel powder, heat to 50°C, keep stirring for 5 h, raise the temperature to 90°C and maintain for 5 min to terminate the enzymatic hydrolysis reaction, and cool to room temperature to obtain an enzymatic hydrolysate.

[0046] The composite enzyme is composed of pectinase, β-glucosidase, tannase and papain mixed in a mass ratio of 1:0.5:2:0.5.

[0047] (2) Add ethanol with a volume fraction of 95% equal to 1 time the weight of the enzymatic hydrolysate to the enzymatic hydrolysate, mix evenly, heat the mixed solution to 50°C, stir and extract for 2 h, then filter through a 400-mesh filter screen. The filtrate is rotary evaporated at 50°C until the volume is reduced to 5% of that before rotary evaporation to stop, obtaining an extract concentrate.

[0048] (3) Prepare sodium alginate with a concentration of 3% and heat it to 60°C, keep stirring evenly. After it is fully swollen, take it out and cool it, place it on a magnetic stirrer, and add the extract concentrate while stirring according to the mass ratio of sodium alginate to the extract concentrate of 4:1 to obtain a mixed solution. Spray the mixed solution into a chitosan composite solution containing 0.8% chitosan and 6% CaCl2 by mass fraction with a spray gun with a pore size of 0.8 mm, let it stand for 30 min, filter, wash the surface of the microcapsules with distilled water to remove moisture, and perform vacuum drying to obtain pomegranate peel extract.

[0049] The steps of vacuum drying are as follows: during the pre-freezing process, the temperature is -45°C and the treatment time is 2 h; during the first sublimation process, the temperature is 0°C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the second sublimation process, the temperature is 5°C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the third sublimation process, the temperature is 15°C, the vacuum degree is 10 Pa, and the treatment time is 1 h.

[0050] Comparative Example 1:

[0051] (1) Clean the big green-skinned pomegranate peels, dry them at 50°C until constant weight, then crush them, pass through a 40-mesh sieve to obtain pomegranate peel powder. Mix the pomegranate peel powder and water in a mass ratio of 1:12, stir evenly, add citric acid to adjust the pH of the mixed solution to 5.0, add papain accounting for 0.02% of the weight of the pomegranate peel powder, heat to 55°C, keep stirring for 6 h, raise the temperature to 90°C and maintain for 5 min to terminate the enzymatic hydrolysis reaction, and cool to room temperature to obtain an enzymatic hydrolysate;

[0052] (2) Add ethanol with a volume fraction of 95% which is 1.5 times the weight of the enzymatic hydrolysate to the enzymatic hydrolysate, mix evenly, heat the mixed solution to 50°C, stir and extract for 1 h, then filter through a 400-mesh filter screen, and perform rotary evaporation on the filtrate at 50°C until the volume is reduced to 5% of that before rotary evaporation and then stop to obtain a concentrated extract;

[0053] (3) Prepare sodium alginate with a concentration of 3% and heat to 60°C, keep stirring evenly. After it swells sufficiently, take it out and cool, place it on a magnetic stirrer, and add the concentrated extract while stirring according to the mass ratio of sodium alginate to the concentrated extract of 3:1 to obtain a mixed solution. Spray the mixed solution into a chitosan composite solution containing 0.8% by mass of chitosan and 6% by mass of CaCl₂ with a spray gun with a pore size of 0.8 mm, let it stand for 30 min, filter, wash the surface of the microcapsules with distilled water to remove moisture, and perform vacuum drying to obtain pomegranate peel extract;

[0054] The steps of vacuum drying are as follows: during the pre-freezing treatment, the temperature is -45°C and the treatment time is 2 h; during the first sublimation process, the temperature is 0°C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the second sublimation process, the temperature is 5°C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the third sublimation process, the temperature is 15°C, the vacuum degree is 10 Pa, and the treatment time is 1 h.

[0055] Comparative Example 2:

[0056] (1) Clean the big green-skinned pomegranate peels, dry them at 50°C until constant weight, then crush them, pass through a 40-mesh sieve to obtain pomegranate peel powder. Mix the pomegranate peel powder and water in a mass ratio of 1:12, stir evenly, add citric acid to adjust the pH of the mixed solution to 5.0, add a compound enzyme accounting for 0.02% of the weight of the pomegranate peel powder, heat to 55°C, keep stirring for 6 h, raise the temperature to 90°C and maintain for 5 min to terminate the enzymatic hydrolysis reaction, and cool to room temperature to obtain an enzymatic hydrolysate;

[0057] The compound enzyme is composed of pectinase and papain mixed in a mass ratio of 2:1;

[0058] (2) Add ethanol with a volume fraction of 95% and a weight 1.5 times that of the enzymatic hydrolysate to the enzymatic hydrolysate, mix evenly, heat the mixture to 50 °C, stir and extract for 1 h, then filter through a 400-mesh filter screen. The filtrate is rotary evaporated at 50 °C until the volume is reduced to 5% of that before rotary evaporation, and the concentrated extract solution is obtained;

[0059] (3) Prepare sodium alginate with a concentration of 3% and heat it to 60 °C. Keep stirring evenly during heat preservation. After it is fully swollen, take it out and cool it. Place it on a magnetic stirrer, and add the concentrated extract solution while stirring according to the mass ratio of sodium alginate to the concentrated extract solution of 3:1 to obtain a mixed solution. Spray the mixed solution into a chitosan composite solution containing 0.8% chitosan and 6% CaCl2 by mass fraction with a spray gun with a pore size of 0.8 mm, let it stand for 30 min, filter, wash the surface of the microcapsules with distilled water to remove moisture, and perform vacuum drying to obtain pomegranate peel extract;

[0060] The steps of vacuum drying are as follows: during the pre-freezing treatment, the temperature is -45 °C and the treatment time is 2 h; during the first sublimation process, the temperature is 0 °C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the second sublimation process, the temperature is 5 °C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the third sublimation process, the temperature is 15 °C, the vacuum degree is 10 Pa, and the treatment time is 1 h.

[0061] Comparative Example 3:

[0062] (1) Wash the big green peel pomegranate peel clean, dry it at 50 °C to constant weight and then crush it, pass it through a 40-mesh sieve to obtain pomegranate peel powder. Mix the pomegranate peel powder and water evenly according to the mass ratio of 1:12, add citric acid to adjust the pH of the mixed solution to 5.0, add a composite enzyme accounting for 0.02% of the weight of the pomegranate peel powder, heat it to 55 °C, keep stirring for 6 h, raise the temperature to 90 °C and keep it for 5 min to terminate the enzymatic hydrolysis reaction, and cool it to room temperature to obtain the enzymatic hydrolysate;

[0063] The composite enzyme is composed of β-glucosidase and papain mixed according to the mass ratio of 1:1;

[0064] (2) Add ethanol with a volume fraction of 95% and a weight 1.5 times that of the enzymatic hydrolysate to the enzymatic hydrolysate, mix evenly, heat the mixture to 50 °C, stir and extract for 1 h, then filter through a 400-mesh filter screen. The filtrate is rotary evaporated at 50 °C until the volume is reduced to 5% of that before rotary evaporation, and the concentrated extract solution is obtained;

[0065] (3) Prepare sodium alginate with a concentration of 3% and heat it to 60°C. Keep it warm and stir evenly. After it has fully swollen, take it out and cool it. Place it on a magnetic stirrer and add the extract concentrate while stirring according to the mass ratio of sodium alginate to extract concentrate of 3:1 to obtain a mixed solution. Spray the mixed solution into a chitosan composite solution containing 0.8% chitosan and 6% CaCl₂ by mass fraction using a spray gun with a pore size of 0.8 mm. Let it stand for 30 min, filter, wash the moisture on the surface of the microcapsules with distilled water, and perform vacuum drying to obtain pomegranate peel extract;

[0066] The steps of vacuum drying are as follows: During the pre-freezing process, the temperature is -45°C and the treatment time is 2 h; during the first sublimation process, the temperature is 0°C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the second sublimation process, the temperature is 5°C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the third sublimation process, the temperature is 15°C, the vacuum degree is 10 Pa, and the treatment time is 1 h.

[0067] Comparative Example 4:

[0068] (1) Wash the big green peel pomegranate peel clean, dry it at 50°C until constant weight, then crush it and pass it through a 40-mesh sieve to obtain pomegranate peel powder. Mix the pomegranate peel powder and water according to the mass ratio of 1:12 and stir evenly. Add citric acid to adjust the pH of the mixed solution to 5.0. Add a composite enzyme accounting for 0.02% of the weight of the pomegranate peel powder, heat it to 55°C, keep it warm and stir for 6 h, raise the temperature to 90°C and maintain it for 5 min to terminate the enzymatic hydrolysis reaction, and cool it to room temperature to obtain an enzymatic hydrolysate;

[0069] The composite enzyme is composed of tannase and papain mixed according to the mass ratio of 3:1;

[0070] (2) Add ethanol with a volume fraction of 95% which is 1.5 times the weight of the enzymatic hydrolysate to the enzymatic hydrolysate, mix evenly, heat the mixed solution to 50°C, stir and extract for 1 h, then filter it through a 400-mesh filter screen. The filtrate is rotary evaporated at 50°C until the volume is reduced to 5% of that before rotary evaporation and then stop to obtain an extract concentrate;

[0071] (3) Prepare sodium alginate with a concentration of 3% and heat it to 60°C. Keep it warm and stir evenly. After it has fully swollen, take it out and cool it. Place it on a magnetic stirrer and add the extract concentrate while stirring according to the mass ratio of sodium alginate to extract concentrate of 3:1 to obtain a mixed solution. Spray the mixed solution into a chitosan composite solution containing 0.8% chitosan and 6% CaCl₂ by mass fraction using a spray gun with a pore size of 0.8 mm. Let it stand for 30 min, filter, wash the moisture on the surface of the microcapsules with distilled water, and perform vacuum drying to obtain pomegranate peel extract;

[0072] The steps of vacuum drying are as follows: during the pre-freezing treatment, the temperature is -45°C and the treatment time is 2 h; during the first sublimation process, the temperature is 0°C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the second sublimation process, the temperature is 5°C, the vacuum degree is 10 Pa, and the treatment time is 4 h; during the third sublimation process, the temperature is 15°C, the vacuum degree is 10 Pa, and the treatment time is 1 h.

[0073] Experimental Example 1: Analysis of the total phenol and total flavonoid contents of different pomegranate peel extracts:

[0074] The pomegranate peel extracts prepared in Example 1 and Comparative Examples 1-4 were formulated into a sample solution with a mass percentage of 0.1% for later use;

[0075] Determination of total phenol content: Add 5 mL of deionized water and 1 mL of Folin-Ciocalteu reagent to 1 mL of the sample solution to obtain a mixture, and let it stand at 25°C for 10 min. Add 4 mL of 70% sodium carbonate solution to the mixture, and after standing at 25°C for 2 h, measure its absorbance at 765 nm. Use gallic acid standard to draw a standard curve, and the result is expressed as milligrams of gallic acid equivalent per gram of sample (mg GAE / g).

[0076] Determination of total flavonoid content: Mix 1 mL of the sample solution with 2 mL of methanol and centrifuge at 8000 r / min for 15 min. Collect 1 mL of the supernatant and mix it with 0.5 mL of 5% sodium nitrite and 0.5 mL of 10% aluminum nitrate in sequence. React for 6 min at 25°C after adding each reagent. Finally, add 4 mL of 4% sodium hydroxide and 4 mL of 60% ethanol, and after reacting at 25°C for 15 min, measure its absorbance at 510 nm. Use rutin as the standard to draw a standard curve, and the result is described as milligrams of rutin equivalent per gram of sample (mg RE / mL).

[0077] Table 1 Total phenol and total flavonoid contents in the pomegranate peel extracts prepared in Example 1 and Comparative Examples 1-4

[0078] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Total phenol content (mg GAE / g) 56.80 30.33 38.78 35.64 39.28 Total flavonoid content (mg RE / mL) 9.07 6.50 7.29 7.09 7.26

[0079] As can be seen from Table 1, the total phenol and total flavonoid contents in the pomegranate peel extract prepared in Example 1 of the present invention are significantly higher than those of other treatment groups.

[0080] Experimental Example 2: Determination of DPPH scavenging rate

[0081] Index description: The higher the DPPH scavenging rate, the better the antioxidant property of the sample.

[0082] The pomegranate peel extracts prepared in Example 1 and Comparative Examples 1-4 were respectively mixed with sterile water to prepare a sample solution with a mass fraction of 5%, and a DPPH free radical scavenging test was carried out.

[0083] The specific steps are as follows:

[0084] (1) Construct a reaction system for the DPPH free radical scavenging test according to the addition amounts of each reagent in Table 2;

[0085] Table 2 Addition amounts of each reagent in the reaction system for the DPPH free radical scavenging test

[0086]

[0087] (2) Place the reaction system at room temperature for reaction for 20 min. After the reaction ends, successively take 200 μL of the reaction solution of each group and add it to a 96-well plate, read the absorbance value (OD value) at 517 nm, and calculate the DPPH free radical scavenging rate. The results are shown in Table 2. Among them, the calculation formula for the DPPH free radical scavenging rate is as follows:

[0088] DPPH free radical scavenging rate (%) = [1 - (OD T1 - OD T2 ) / (OD C1 - OD C2 )] × 100%;

[0089] In the formula, OD T1 is the absorbance value of group T1 at 517 nm, OD T2 is the absorbance value of group T2 at 517 nm, OD C1 is the absorbance value of group C1 at 517 nm, OD C2 is the absorbance value of group C1 at 517 nm.

[0090] Table 3 DPPH free radical scavenging rate

[0091] Group DPPH radical scavenging rate (%) Example 1 71.08 Comparative Example 1 51.70 Comparative Example 2 53.28 Comparative Example 3 55.21 Comparative Example 4 58.53

[0092] As can be seen from Table 3, the DPPH free radical scavenging rate of the pomegranate peel extract prepared in Example 1 of the present invention reaches 71.08%.

[0093] Test Example 3: Determination of tyrosinase inhibition rate

[0094] Index description: The higher the tyrosinase inhibition rate, the better the whitening effect of the sample.

[0095] The pomegranate peel extracts prepared in Example 1 and Comparative Examples 1-4 were respectively mixed with sterile water to prepare a sample solution with a mass fraction of 1%, and the tyrosinase inhibition rate was measured.

[0096] Reagent preparation:

[0097] Disodium hydrogen phosphate-citric acid buffer solution with pH 6.8

[0098] ① 0.2 mol / L Na2HPO4·12H2O: Dissolve 14.33 g in 200 mL of water and stir with a glass rod until dissolved;

[0099] ② 0.1 mol / L citric acid monohydrate: Dissolve 2.1 g in 100 mL of water and stir with a glass rod until dissolved;

[0100] ③ Sodium hydrogen phosphate-citric acid buffer solution at pH 6.8: Add 154.5 mL of 0.2 mol / L Na2HPO4·12H2O and 45.5 mL of 0.1 mol / L citric acid monohydrate to prepare 200 mL of sodium hydrogen phosphate-citric acid buffer solution;

[0101] Tyrosinase solution: Prepared with sodium hydrogen phosphate-citric acid buffer solution at pH 6.8, 100 u / mL, prepared immediately before use;

[0102] L-DOPA solution: Prepared with sodium hydrogen phosphate-citric acid buffer solution at pH 6.8, 1 mg / mL, stored in the dark;

[0103] Experimental procedure:

[0104] (1) Construct a tyrosinase inhibition test reaction system according to the addition amounts of each reagent in Table 4;

[0105] Table 4 Requirements for adding liquid to samples

[0106] T - sample tube <![CDATA[T0 - Sample background]]> C - enzyme reaction tube <![CDATA[C0 - Solvent Background]]> Sample solution (mL) 1 1 - - Disodium hydrogen phosphate - citric acid buffer solution (mL) - 0.5 1 1.5 Tyrosinase solution (mL) 0.5 - 0.5 - Levodopa solution (mL) 2 2 2 2 Number of parallel tests 3 / sample 1 / sample 3 / tests 1 / test

[0107] (2) Add 1 mL of the sample solution with the same concentration to each of the sample tube (T) and the sample background (T0), and add 1 mL of sodium hydrogen phosphate-citric acid buffer solution to the enzyme reaction tube (C) and the solvent background (C0) respectively.

[0108] Add 0.5 mL of tyrosinase solution to each of the sample tube (T) and the enzyme reaction tube (C), replace 0.5 mL of sodium hydrogen phosphate-citric acid buffer solution for the sample background (T0) and the solvent background (C0), mix the sample and tyrosinase well, and incubate in a 37 °C water bath for 10 minutes.

[0109] Add 2 mL of L-DOPA solution to each tube in sequence, control the reaction time of each tube to be 5 minutes, immediately transfer the reaction solution of each tube into a cuvette, and measure the absorbance at 475 nm.

[0110] (3) Calculate the tyrosinase inhibition rate:

[0111]

[0112] Where:

[0113] T—Absorbance value of the sample tube, that is, the absorbance value of the solution after the reaction of the sample and tyrosinase;

[0114] T0—Absorbance value of the sample background

[0115] C—Average value of the absorbance of the enzyme reaction tube measured three times, that is, the absorbance of the reaction between tyrosinase and dopa without adding the sample

[0116] C0—Absorbance value of the solvent background

[0117] Table 5 Tyrosinase inhibition rate

[0118]

[0119]

[0120] As can be seen from Table 5, the pomegranate peel extract prepared in Example 1 of the present invention has a relatively high inhibition rate on tyrosinase, up to 55.43%.

[0121] Test Example 4: Test on the whitening effect of human face

[0122] The pomegranate peel extracts prepared in Example 1 and Comparative Examples 1-4 were respectively mixed with sterile water to prepare a sample solution with a mass fraction of 5%, and the whitening effect test of the human face was carried out.

[0123] The human efficacy test evaluation method was adopted. Subjects were selected: 150 subjects, male and female subjects aged 24-37 years old, with good health and meeting the volunteer selection criteria for subjects. The subjects were divided into 5 groups, with 30 people in each group, and they used the sample solutions prepared by mixing the pomegranate peel extracts prepared in Example 1 and Comparative Examples 1-4 with sterile water respectively.

[0124] Test instrument: Cotometer MPA580 mainframe, Mexameter MX18 probe, Colorimeter CL400 manufactured by Courage+Khazaka GmbH (German CK company);

[0125] Detection location: 6th floor, Building 3, Borke Headquarters, Gangxingyuan Road, Licheng District, Jinan City, Shandong Province;

[0126] Test environment: Temperature 21.0°C ± 1°C, relative humidity 50% ± 10%RH;

[0127] Test process: 90 subjects used Test Sample 1, Comparative Sample 2, and Comparative Sample 3 respectively. First, the blank value was measured 30 minutes after the test area was cleaned, and then the subjects were required to use the above test products every morning and evening. The melanin content (MI value) and individual type angle (ITA°) of the test area were measured after 14 days and 28 days of use respectively, and the average value was taken after measuring five times.

[0128] Index description:

[0129] Melanin content (MI value): The smaller the MI value, the lower the melanin content of the skin; conversely, the higher the melanin content of the skin.

[0130] Individual type angle (ITA°): The larger the ITA° value, the lighter the skin color; conversely, the darker the skin color.

[0131] Melanin content change rate % = [(Melanin content after trial - Melanin content before trial) / Melanin content before trial] × 100%.

[0132] Individual type angle change rate % = [(Individual type angle after trial - Individual type angle before trial) / Individual type angle before trial] × 100%.

[0133] Table 6 Melanin content change rate (n = 30)

[0134]

[0135]

[0136] Table 7 Individual type angle change rate (n = 30)

[0137]

[0138] As can be seen from Table 6 and Table 7, after using the pomegranate peel extract prepared in Example 1 of the present invention, the melanin content of the subjects can be significantly reduced, and the individual type angle of the subjects can be significantly increased.

[0139] Test Example 5: Stability test

[0140] Prepare a cream, add the pomegranate peel extracts prepared in Examples 1 - 3 to the cream respectively, and place it in an open environment at 50°C for 5 days to test the stability.

[0141] (1) Cream raw material table

[0142] Table 8 Cream raw material table

[0143]

[0144]

[0145] (2) Cream preparation process

[0146] Heat the purified water to 80°C, and add glycerol, sodium stearoyl glutamate, carbomer, 1,2 - hexanediol, and p - hydroxyacetophenone during the heating process, and homogenize and disperse evenly to form an aqueous phase;

[0147] Mix caprylic / capric triglyceride, polydimethylsiloxane, cetyl alcohol, stearyl alcohol, and phytosqualane evenly, heat to 85 °C, and stir until the raw materials are completely dissolved to form an oil phase;

[0148] Slowly pour the oil phase into the water phase under the condition of homogenization until emulsified evenly;

[0149] Cool down to 45 °C, add dissolved arginine, and stir evenly to obtain the facial cream.

[0150] Take three groups of facial creams of equal mass respectively, add the pomegranate peel extracts prepared in Examples 1-3 at 0.5% of the mass of the facial cream to obtain samples. Place the three groups of samples in an open environment at 50 °C for 5 days, and evaluate the appearance and pH value.

[0151] Appearance evaluation criteria:

[0152] Stable: A (no color change, no precipitation, no odor change);

[0153] Less stable: B (slight color change, or slight precipitation, or slight odor change);

[0154] Unstable: C (significant color change, or obvious precipitation, or large odor change).

[0155] Table 9 Stability test results of pomegranate peel extracts in Examples 1-3

[0156] Sample pH value Appearance evaluation Example 1 6.12 A Example 2 6.13 A Example 3 6.11 A

[0157] As can be seen from Table 9, when the pomegranate peel extracts prepared in Examples 1-3 of the present invention are added to the facial cream, the facial cream can maintain stability.

[0158] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A pomegranate peel extract, characterized in that, Prepared by the following method: (1) Add pomegranate peel powder to water and a complex enzyme for enzymatic hydrolysis to obtain a pomegranate peel enzymatic hydrolysate; (2) Add an ethanol solution with a volume fraction of 90 - 99% to the pomegranate peel enzymatic hydrolysate, heat for extraction, filter and rotary evaporate to obtain a concentrated extract; (3) Add the concentrated extract to a sodium alginate solution to obtain a mixed solution, spray the mixed solution into a chitosan composite solution, stand, wash, and vacuum freeze-dry to obtain a pomegranate peel extract.

2. The pomegranate peel extract according to claim 1, wherein In step (1), the specific steps of enzymatic hydrolysis are: Mix pomegranate peel powder and water at a mass ratio of 1:(8 - 15), add citric acid to adjust the pH to 4.5 - 5.5, then add a complex enzyme accounting for 0.01% - 0.03% of the weight of the pomegranate peel powder, heat to 50 - 60°C, stir for 5 - 8 h, raise the temperature to 85 - 95°C and maintain for 3 - 7 min, then cool down to obtain a pomegranate peel enzymatic hydrolysate.

3. The pomegranate peel extract according to claim 2, wherein The complex enzyme is composed of pectinase, β-glucosidase, tannase and papain mixed in a mass ratio of (1 - 3):(0.5 - 1.5):(2 - 4):(0.5 - 1.5).

4. The pomegranate peel extract according to claim 1, wherein In step (2), the mass ratio of the pomegranate peel enzymatic hydrolysate to the ethanol solution is 1:(1 - 2).

5. The pomegranate peel extract according to claim 1, wherein In step (2), the extraction temperature is 40 - 60°C and the extraction time is 0.5 - 2 h; the rotary evaporation temperature is 40 - 60°C, and rotary evaporation stops when the volume is reduced to 4 - 6% of that before rotary evaporation.

6. The pomegranate peel extract according to claim 1, wherein In step (3), the preparation method of the sodium alginate solution is: add sodium alginate to water to make its mass fraction 2 - 4%, heat to 50 - 70°C, stir, and cool to obtain a sodium alginate solution.

7. The pomegranate peel extract according to claim 1, wherein In step (3), the mass ratio of sodium alginate to the concentrated extract is (2 - 4):

1.

8. The pomegranate peel extract according to claim 1, characterized in that, In step (3), the mixed solution is sprayed into the chitosan composite solution with a spray gun with a pore size of 0.6 - 1.0 mm. The chitosan composite solution is an aqueous solution containing 0.5% - 1% chitosan and 5 - 8% CaCl2 by mass fraction, and the standing time is 20 - 40 min.

9. The pomegranate peel extract according to claim 1, wherein, In step (3), the vacuum freeze-drying process is: during the pre-freezing process, the temperature is -50 to -40°C and the treatment time is 1 - 3 h; during the first sublimation process, the temperature is -5 - 5°C, the vacuum degree is 5 - 15 Pa, and the treatment time is 3 - 5 h; during the second sublimation process, the temperature is -5 - 5°C, the vacuum degree is 5 - 15 Pa, and the treatment time is 3 - 5 h; during the third sublimation process, the temperature is 10 - 20°C, the vacuum degree is 5 - 15 Pa, and the treatment time is 0.5 - 1.5 h.

10. Use of the pomegranate peel extract according to any one of claims 1 - 9 in the preparation of a product for whitening or antioxidant.

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