Method for extracting anthocyanin in black plum bark

Abstract

The invention relates to a method for extracting anthocyanin in black plum bark, and belongs to the technical field of natural product extraction. The method comprises the following steps: drying and crushing black plum bark, adding a deep-eutectic solvent, and fully and uniformly mixing to obtain a mixed solution; extracting an anthocyanin crude extracting solution from the mixed solution by adopting an ultrasonic extraction method; extracting the crude extracting solution by adopting a supercritical extraction method to obtain an anthocyanin extracting solution; freezing and centrifuging the anthocyanin extracting solution to obtain supernate; separating and purifying the obtained anthocyanin supernate by adopting a micro-fluidic membrane separation technology to obtain a purified anthocyanin solution; and removing excessive water in the anthocyanin solution by using a rotary evaporator to obtain the target product anthocyanin. The method has the advantages that the eutectic solvent is used as an extraction solvent, the extraction time is short, the method is environment-friendly, the preparation process is simple, and purification is not needed; when the deep eutectic solvent is used as an extraction solvent to extract the plant anthocyanin, ultrasonic and supercritical extraction is assisted, so that the extraction efficiency is effectively improved, and the color of natural substances is kept; by adopting a micro-fluidic membrane separation technology for separation and purification, the operation is simple, and the effect is good.

Description

Technical Field

[0001] The present invention belongs to the technical field of natural product extraction, and relates to a method for extracting anthocyanins from black plum peel. Background Art

[0002] Natural anthocyanins have the advantages of safety, non-toxicity, rich resources, etc. And pharmacological studies have found that anthocyanins have various biological activities such as antioxidant, immune enhancement, anti-tumor, lipid-lowering and blood sugar-lowering. At present, anthocyanins have been successfully used in the treatment of low immunity, joint inflammation, urinary tract infection, myopia, and the development of functional health products. The black plum fruit contains rich components such as amino acids, vitamins, fruit acids, etc., and has high nutritional value. However, a large amount of peel waste will be generated during the processing of black plum products and has not been effectively developed and utilized. And a large amount of anthocyanins are contained in the black plum peel. If directly discarded, it will inevitably cause serious waste of resources. Therefore, efficiently extracting anthocyanins from the peel will be a better way of comprehensive utilization.

[0003] Anthocyanins are usually extracted using traditional organic solvents such as ethanol and acetone. Although the chemical reagents used are relatively cheap, the equipment is simple, easy to operate, and the extraction rate is relatively high. But on the one hand, the time used for its leaching and filtration is long, the separation and purification of the product are difficult, and the product concentration is low; on the other hand, it is easy to have peculiar smell or solvent residue, thus limiting its application scope. And deep eutectic solvents are mainly composed of organic salts such as quaternary ammonium salts and quaternary phosphonium salts as hydrogen bond acceptors and carboxylic acids, amides, alcohols, etc. as hydrogen bond donors. They have the properties of low vapor pressure, excellent solubility and conductivity, wide electrochemical stability window and other ionic liquid properties. At the same time, they have the characteristics of low cost, simple preparation, non-toxicity, biodegradability, easy availability, etc., and the atom utilization rate in the synthesis process reaches 100%. It is a new type of green solvent. Therefore, deep eutectic solvents can replace traditional organic solvents as a new and efficient extractant. When using deep eutectic solvents as extraction solvents to extract plant anthocyanins, ultrasonic and supercritical extraction are supplemented to effectively improve the extraction efficiency and maintain the color of natural substances; the use of microfluidic membrane separation technology for separation and purification is simple in operation and good in effect. Summary of the Invention

[0004] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a method for extracting anthocyanins from black plum peel.

[0005] To achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for extracting anthocyanins from black plum peel. Using deep eutectic solvents as extraction solvents, the reaction energy consumption is small, green and environmentally friendly, and the extraction process is simple; ultrasonic and supercritical assisted extraction and microfluidic purification are adopted to make the extraction time short and the extraction rate higher. The process is as follows: (1) Dry and crush the black plum peel, add it to the deep eutectic solvent, and mix well to obtain a mixed solution; (2) Use ultrasonic extraction method to extract anthocyanin crude extract from the mixed solution; (3) Use supercritical extraction method to extract the crude extract to obtain anthocyanin extract; (4) Centrifuge the anthocyanin extract at low temperature to obtain anthocyanin supernatant; (5) Use microfluidic membrane separation technology to separate and purify the obtained anthocyanin supernatant to obtain purified anthocyanin solution; (6) Use a rotary evaporator to remove the excess water in the anthocyanin solution to obtain the target product anthocyanin.

[0006] Preferably, the deep eutectic solvent is prepared by the following method: Weigh a hydrogen bond acceptor with a mass of m, add a hydrogen bond donor according to the molar ratio of hydrogen bond acceptor to donor of 1:1 - 10, stir magnetically at 80 °C and 40 rpm until it dissolves into a colorless and transparent liquid, then a deep eutectic solvent with a specific molar ratio can be prepared. After that, transfer it to a vacuum drying oven, and dry it thoroughly with P2O5 for later use.

[0007] Preferably, the hydrogen bond acceptor is any one or a combination of the following: choline chloride, choline tartrate, choline acetate, choline nitrate, alanine, betaine hydrochloride, nicotinic acid, glycine; the hydrogen bond donor is any one or a combination of the following: lactic acid, acetic acid, citric acid, malic acid, tartaric acid, maleic acid, acrylic acid, malonic acid, oxalic acid, maleic anhydride, propanetricarboxylic acid.

[0008] Preferably, the solid-liquid ratio of the mixed solution is 1 g:5 - 30 mL.

[0009] Preferably, the conditions for ultrasonic extraction are: ultrasonic power is 100 - 500 W, ultrasonic temperature is 50 - 70 °C, and ultrasonic time is 10 - 50 min.

[0010] Preferably, the conditions for supercritical extraction are: supercritical extraction temperature is 30 - 60 °C, supercritical extraction time is 30 - 60 min, supercritical extraction pressure is 20 - 30 MPa, and the CO2 flow rate is 5 - 10 L / min.

[0011] Preferably, the centrifugation conditions are: 4 °C, 2000 - 3000 rpm, 20 - 30 min.

[0012] Preferably, the purification step of the microfluidic membrane separation technology is: The syringe is inserted into the injection pump, and under the drive of the pump, the anthocyanin supernatant is introduced at the sampling port. The flow rate of the injection pump is controlled to form a stable interface. After physical screening and membrane separation through the flow channel, the purified anthocyanin solution is collected at the outlet.

[0013] Preferably, the length of the physical screening flow channel membrane is 20 - 40 mm, and the pore size is 3 - 8 μm.

[0014] Preferably, the rotary evaporation conditions are: 100 - 120 rpm, 50 - 60 °C until completely evaporated to dryness.

[0015] The present invention has the following beneficial effects: In the method for extracting anthocyanins from black plum peels provided by the present invention, a deep eutectic solvent is used as the extraction solvent, with a short extraction time, being green and environmentally friendly. Compared with ionic liquids, the raw materials of deep eutectic solvents are cheap and easily available, no solvents are used in the preparation process, the process is simple and purification is not required, the atom utilization rate reaches 100%, and it is environmentally friendly, etc. When using a deep eutectic solvent as the extraction solvent to extract plant anthocyanins, ultrasonic and supercritical extraction are supplemented to effectively improve the extraction efficiency and maintain the color of natural substances; the separation and purification using microfluidic membrane separation technology is simple in operation and has good effects. Description of the Drawings

[0016] Figure 1 It is a practical diagram of the anthocyanin solution extracted in the embodiment of the present application; Figure 2 It is a schematic flow chart of the method for extracting anthocyanins from black plum peels provided by the present application; Figure 3 It is a front top view structural schematic diagram of the microfluidic chip used in the present application. Detailed Embodiments

[0017] The embodiment of the present application provides a method for extracting anthocyanins from black plum peels. As shown in the attached Figure 2 figures, the method specifically includes: (1) After drying and pulverizing the black plum peels, add a deep eutectic solvent and mix well to obtain a mixed solution; (2) Use ultrasonic extraction to extract the anthocyanin crude extract from the mixed solution; (3) Use supercritical extraction to extract the crude extract to obtain an anthocyanin extract; (4) Centrifuge the anthocyanin extract by freezing to obtain an anthocyanin supernatant; (5) Use the microfluidic chip shown in the attached Figure 3 figures to separate and purify the obtained anthocyanin supernatant according to the microfluidic membrane separation technology to obtain a purified anthocyanin solution; (6) Excess water in the anthocyanin solution was removed using a rotary evaporator to obtain the target product anthocyanin. The product diagram of the anthocyanin solution is as attached Figure 1 as shown.

[0018] The technical solutions of the present invention will be further explained and illustrated through specific embodiments below.

[0019] Embodiment 1: This embodiment provides a method for extracting anthocyanins from black plum peel. 10 g of black plum peel powder that has been dried, pulverized, and passed through a 100-mesh sieve was taken, and the eutectic solvent choline chloride-glycerol (molar ratio 1:3, water content 20%wt) was used as the extraction solvent. Under the conditions of a solid-liquid ratio of 1 g:10 mL, an ultrasonic power of 300 W, and an extraction temperature of 50 °C, extraction was carried out for 20 min to obtain an anthocyanin extract; the anthocyanin extract was centrifuged by freezing to obtain a supernatant; the obtained anthocyanin supernatant was separated and purified using a microfluidic membrane separation technique to obtain a purified anthocyanin solution; excess water in the anthocyanin solution was removed using a rotary evaporator to obtain the target product anthocyanin. The extraction rate of anthocyanin was 1.8615 mg / g.

[0020] Embodiment 2: This embodiment provides a method for extracting anthocyanins from black plum peel. 10 g of black plum peel powder that has been dried, pulverized, and passed through a 100-mesh sieve was taken, and the eutectic solvent choline chloride-urea (molar ratio 1:2, water content 20%wt) was used as the extraction solvent. Under the conditions of a solid-liquid ratio of 1 g:30 mL, an ultrasonic power of 100 W, and an extraction temperature of 50 °C, extraction was carried out for 30 min to obtain an anthocyanin extract; the anthocyanin extract was centrifuged by freezing to obtain a supernatant; the obtained anthocyanin supernatant was separated and purified using a microfluidic membrane separation technique to obtain a purified anthocyanin solution; excess water in the anthocyanin solution was removed using a rotary evaporator to obtain the target product anthocyanin. The extraction rate of anthocyanin was 1.9425 mg / g.

[0021] Embodiment 3: This embodiment provides a method for extracting anthocyanins from black plum peel. 10 g of black plum peel powder that has been dried, pulverized, and passed through a 100-mesh sieve was taken, and the eutectic solvent choline chloride-ethylene glycol (molar ratio 1:3, water content 20%wt) was used as the extraction solvent. Under the conditions of a solid-liquid ratio of 1 g:20 mL, an ultrasonic power of 400 W, and an extraction temperature of 60 °C, extraction was carried out for 30 min to obtain an anthocyanin extract; the anthocyanin extract was centrifuged by freezing to obtain a supernatant; the obtained anthocyanin supernatant was separated and purified using a microfluidic membrane separation technique to obtain a purified anthocyanin solution; excess water in the anthocyanin solution was removed using a rotary evaporator to obtain the target product anthocyanin. The extraction rate of anthocyanin was 2.0895 mg / g.

[0022] Embodiment 4: This embodiment provides a method for extracting anthocyanins from black plum peel. Take 10 g of black plum peel powder that has been dried, crushed, and passed through a 100-mesh sieve. Use the eutectic solvent choline chloride - citric acid (molar ratio 1:2, water content 20% wt) as the extraction solvent. Under the conditions of a solid-liquid ratio of 1 g:20 mL, an ultrasonic power of 250 W, and an extraction temperature of 50 °C, extract for 20 min to obtain an anthocyanin extract. Centrifuge the anthocyanin extract by freezing to obtain the supernatant. Use the microfluidic membrane separation technology to separate and purify the obtained anthocyanin supernatant to obtain a purified anthocyanin solution. Use a rotary evaporator to remove the excess water in the anthocyanin solution to obtain the target product anthocyanin. The extraction rate of anthocyanin is 4.1132 mg / g.

[0023] Embodiment 5: This embodiment provides a method for extracting anthocyanins from black plum peel. Take 10 g of black plum peel powder that has been dried, crushed, and passed through a 100-mesh sieve. Use the eutectic solvent choline chloride - lactic acid (molar ratio 1:2, water content 20% wt) as the extraction solvent. Under the conditions of a solid-liquid ratio of 1 g:20 mL, an ultrasonic power of 300 W, and an extraction temperature of 70 °C, extract for 25 min to obtain an anthocyanin extract. Centrifuge the anthocyanin extract by freezing to obtain the supernatant. Use the microfluidic membrane separation technology to separate and purify the obtained anthocyanin supernatant to obtain a purified anthocyanin solution. Use a rotary evaporator to remove the excess water in the anthocyanin solution to obtain the target product anthocyanin. The extraction rate of anthocyanin is 7.6294 mg / g.

[0024] Among them, the preparation method of the eutectic solvent is as follows: Weigh choline chloride with a mass of m, add a hydrogen bond donor according to the molar ratio of hydrogen bond donor and acceptor, stir magnetically at 80 °C (40 rpm) until it dissolves into a colorless and transparent liquid, then a eutectic solvent with a specific molar ratio can be prepared. After that, transfer it to a vacuum drying oven, dry it thoroughly with P2O5, and set it aside for use.

[0025] Appendix Figure 3 The purification method of the microfluidic membrane separation technology of the microfluidic chip shown is as follows: Insert the syringe into the injection pump. Under the drive of the pump, introduce the centrifuged supernatant at the injection port, control the flow rate of the injection pump to form a stable interface, and collect the purified anthocyanin solution at the outlet after passing through the selective membrane of the physical screening channel.

[0026] Compare the extraction rates of the anthocyanins from black plum peel extracted by Embodiments 1 - 5 with the alcohol extraction method to obtain Table 1.

[0027] Table 1: Comparison results of extraction rates The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various modifications and changes can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for extracting anthocyanins from black plum peel, characterized in that: The following steps are involved: (1) drying and crushing the black plum peel, adding a low eutectic solvent and mixing thoroughly to obtain a mixed solution; (2) extracting anthocyanin crude extract from the mixed solution using ultrasonic extraction method; (3) extracting the crude extract by supercritical extraction to obtain anthocyanin extract; (4) subjecting the anthocyanin extract to refrigerated centrifugation to obtain anthocyanin supernatant; (5) using microfluidic membrane separation technology to separate and purify the obtained anthocyanin supernatant to obtain a purified anthocyanin solution; (6) Use a rotary evaporator to remove excess water from the anthocyanin solution to obtain the target product anthocyanin.

2. The method for extracting anthocyanins from black plum peel according to claim 1, characterized in that: The deep eutectic solvent is prepared by the following method: Weigh a hydrogen bond acceptor with a mass of m, add a hydrogen bond donor according to a molar ratio of 1:1 to 10, stir magnetically at 80°C and 40rpm until it dissolves into a colorless and transparent liquid, and a low eutectic solvent with a specific molar ratio can be prepared. Then transfer it to a vacuum drying oven, dry it thoroughly with P2O5 and set it aside.

3. The method for extracting anthocyanins from black plum peel according to claim 2, characterized in that: The hydrogen bond acceptor is any one of the following or a combination thereof: choline chloride, choline bitartrate, choline acetate, choline nitrate, alanine, betaine hydrochloride, niacin, and glycine; the hydrogen bond donor is any one of the following or a combination thereof: lactic acid, acetic acid, citric acid, malic acid, tartaric acid, maleic acid, acrylic acid, malonic acid, oxalic acid, maleic acid, and propylene tricarboxylic acid.

4. The method for extracting anthocyanins from black plum peel according to claim 1, characterized in that: The solid-liquid ratio of the mixed solution is 1 g: 5~30 mL.

5. The method for extracting anthocyanins from black plum peel according to claim 1, characterized in that: The conditions of the ultrasonic extraction are: ultrasonic power of 100-500 W, ultrasonic temperature of 50-70 °C, and ultrasonic time of 10-50 min.

6. The method for extracting anthocyanins from black plum peel according to claim 1, characterized in that: The supercritical extraction conditions are as follows: supercritical extraction temperature is 30-60°C, supercritical extraction time is 30-60 min, supercritical extraction pressure is 20-30 MPa, and CO2 flow rate is 5-10 L / min.

7. The method for extracting anthocyanins from black plum peel according to claim 1, characterized in that: The centrifugation conditions are: 4°C, 2000-3000 rpm, 20-30 min.

8. The method for extracting anthocyanins from black plum peel according to claim 1, characterized in that: The purification steps of the microfluidic membrane separation technology are as follows: The syringe is embedded in the injection pump, and the anthocyanin supernatant is introduced into the sample inlet under the drive of the pump, and the flow rate of the injection pump is controlled to form a stable interface. After physical screening flow channel membrane separation, the purified anthocyanin solution is collected at the outlet.

9. The method for extracting anthocyanins from black plum peel according to claim 8, characterized in that: The length of the physical screening flow channel membrane is 20-40 mm, and the pore size is 3-8 μm.

10. The method for extracting anthocyanins from black plum peel according to claim 1, characterized in that: The rotary evaporation conditions are: 100-120 rpm, 50-60 °C, until completely evaporated to dryness.

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