A method for extracting polyphenols from pomegranate peel by using a betaine-based deep eutectic solvent

Abstract

The application belongs to the technical field of natural product extraction, and discloses a method for extracting pomegranate peel polyphenols by using a betaine-based deep eutectic solvent, which comprises the following steps: (1) mixing a hydrogen bond acceptor solvent, a hydrogen bond donor solvent and water to obtain a deep eutectic solvent; and (2) mixing the deep eutectic solvent and pomegranate peel powder, and then extracting, and obtaining a pomegranate peel polyphenol extract liquid through centrifugation. The deep eutectic solvent is simple and convenient to operate, safe and environmentally friendly, and realizes efficient extraction of pomegranate peel polyphenols.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of natural product extraction, and particularly relates to a method for extracting polyphenols from pomegranate peel by using a betaine-based deep eutectic solvent. BACKGROUND

[0002] China is rich in pomegranate resources, with an annual output of millions of tons. Pomegranate peel, the main by-product of pomegranate processing, is rich in polyphenols, mainly composed of tannins (mainly punicalagin, punicalin and ellagic acid), flavonoids (mainly quercetin) and active ingredients such as organic acids, and has a wide range of effects and functions such as antioxidant, anti-inflammatory, antibacterial, anticancer and prevention of cardiovascular diseases. It has broad application prospects in the fields of food, medicine and the like. At present, polyphenols are usually extracted using solvents such as water, ethanol, methanol and ethyl acetate or combined with ultrasonic, microwave or enzyme-assisted methods. For example, the team of Gao Shanxing refers to the published literature [Gao Shanxing, Zhang Ruixi, Wang Yutian, et al. Extraction process optimization and antioxidant research of pomegranate peel polyphenols [J]. Food industry, 2023, 44(03): 55-60.] to extract polyphenols from pomegranate peel by using a composite enzyme / ultrasound / 50% ethanol extraction method. After 40 minutes of enzyme hydrolysis and 15 minutes of ultrasonic treatment at 60℃, 200.32 mg GAE / g of polyphenols was obtained. The team of Deng Yong [Deng Yong, Liu Donghong. Effect of ultrasonic treatment on the extraction of polyphenols from pomegranate peel [J]. Journal of food science and technology, 2021, 39(01): 65-69+77] used water as the extraction solvent and extracted polyphenols from pomegranate peel by ultrasonic treatment at 400W for 25 minutes, obtaining 39.30 mg GAE / g of polyphenols. Although enzyme-assisted and ultrasonic-assisted methods can improve the extraction yield of polyphenols, they generally use organic solvents, which have problems such as large solvent consumption, environmental protection and safety.

[0003] In recent years, green and efficient deep eutectic solvents have been widely used in the extraction of natural products. Deep eutectic solvents are two-component or three-component deep eutectic mixtures composed of a certain stoichiometric ratio of hydrogen bond acceptors and hydrogen bond donors through heating, stirring or reduced pressure concentration, etc. They have the characteristics of simple operation, high extraction efficiency, low synthesis cost, safety, non-toxicity and environmental friendliness. However, due to the large number of hydrogen bond donors and acceptors, and the significant differences in the extraction of polyphenols from different plant materials, it is necessary to develop new deep eutectic solvent systems for the efficient extraction of polyphenols, in order to expand the range of deep eutectic solvents for extracting polyphenols. SUMMARY

[0004] The purpose of the present application is to provide a method for extracting polyphenols from pomegranate peel by using a betaine-based deep eutectic solvent, in order to solve the problems of large organic solvent consumption and low extraction rate in the extraction of plant polyphenols, and the differences in the extraction of polyphenols by different formulations of deep eutectic solvents.

[0005] In order to achieve the above object, the present application adopts the following technical solutions:

[0006] The present application provides a method for extracting polyphenols from pomegranate peel by using a betaine-based deep eutectic solvent, comprising the following steps:

[0007] (1) mixing a hydrogen bond acceptor solvent, a hydrogen bond donor solvent and water to obtain a deep eutectic solvent;

[0008] (2) mixing the deep eutectic solvent and pomegranate peel powder, then extracting, and then centrifuging to obtain a pomegranate peel polyphenol extract.

[0009] Preferably, the hydrogen bond acceptor solvent comprises anhydrous betaine; the hydrogen bond donor solvent comprises ethanolamine, ethylene glycol or 1,2-butanediol.

[0010] Preferably, the molar ratio of the hydrogen bond acceptor solvent to the hydrogen bond donor solvent is 1:1-3; the water content of the deep eutectic solvent is 14-20% (w / w).

[0011] Preferably, in step (1), the mixing temperature is 75-80℃, and the mixing time is 2-5h.

[0012] Preferably, in step (1), after mixing, the obtained product is allowed to stand to room temperature to obtain the deep eutectic solvent.

[0013] Preferably, the particle size of the pomegranate peel powder is 80-200 meshes; the solid-liquid ratio of the pomegranate peel powder to the deep eutectic solvent is 1g:40-55mL.

[0014] Preferably, in step (2), the extraction temperature is 30-45℃, the extraction time is 20-90min, the ultrasonic power is 80-120W; the centrifugation speed is 5000-8000r / min, and the centrifugation time is 5-10min.

[0015] Preferably, in step (2), after centrifugation, the obtained supernatant is the pomegranate peel polyphenol extract.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] The deep eutectic solvent disclosed by the present application is simple to prepare, safe and environmentally friendly, and has a high extraction rate, thereby realizing efficient extraction of pomegranate peel polyphenols and promoting the resource utilization of pomegranate peel. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only aim at the embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of the provided drawings.

[0019] Figure 1 Polyphenol extraction effect diagram for Examples 1-3 and Comparative Examples 1-4;

[0020] Figure 2 Polyphenol extraction effect diagram for Examples 1, Examples 4-5 and Comparative Examples 5-6;

[0021] Figure 3 Polyphenol extraction effect diagram for Examples 1, Examples 6-7 and Comparative Examples 7-8;

[0022] Figure 4 Polyphenol extraction effect diagram for Examples 1, Example 8 and Comparative Examples 9-13. DETAILED DESCRIPTION

[0023] The present application provides a method for extracting pomegranate peel polyphenols by betaine-based deep eutectic solvent, comprising the following steps:

[0024] (1) mixing a hydrogen bond acceptor solvent, a hydrogen bond donor solvent and water to obtain a deep eutectic solvent;

[0025] (2) mixing the deep eutectic solvent and pomegranate peel powder for extraction, and then centrifuging to obtain a pomegranate peel polyphenol extract.

[0026] In the present application, the hydrogen bond acceptor solvent comprises anhydrous betaine; the hydrogen bond donor solvent comprises ethanolamine, ethylene glycol or 1,2-butanediol.

[0027] In the present application, the molar ratio of the hydrogen bond acceptor solvent and the hydrogen bond donor solvent is preferably 1:1-3, further preferably 1:2.8; the water content of the deep eutectic solvent is preferably 14-20% (w / w), further preferably 15-19% (w / w), and more preferably 18% (w / w).

[0028] In the step (1) of the present application, the mixing temperature is preferably 75-80℃, further preferably 76-78℃; the mixing time is preferably 2-5h, further preferably 3-4h.

[0029] In the step (1) of the present application, after mixing, the obtained product is allowed to stand to room temperature to obtain a deep eutectic solvent.

[0030] In the present application, the pomegranate peel powder is pretreated before mixing with the deep eutectic solvent; the specific steps of the pretreatment are as follows: the pomegranate peel is dried at 40℃ until the weight is constant, crushed and sieved, and stored in a refrigerator at-20℃ for standby.

[0031] In the present application, the particle size of the pomegranate peel powder is preferably 80-200 mesh, and further preferably 100-150 mesh; the solid-liquid ratio of the pomegranate peel powder and the deep eutectic solvent is preferably 1g:40-55mL, and further preferably 1g:45-50mL.

[0032] In the step (2) of the present application, the extraction temperature is preferably 30-45℃, and further preferably 35-40℃; the extraction time is preferably 20-90min, and further preferably 40-60min; the ultrasonic power is preferably 80-120W, and further preferably 90-100W; the centrifugal speed is preferably 5000-8000r / min, and further preferably 6000-7000r / min; and the centrifugal time is preferably 5-10min, and further preferably 6-8min.

[0033] In the step (2) of the present application, after centrifugation, the obtained supernatant is the pomegranate peel polyphenol extract.

[0034] The technical solutions provided by the present application are described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.

[0035] The preparation of the pomegranate peel powder used in the following examples and comparative examples is as follows: the pomegranate peel is dried at 40℃ until the weight is constant, crushed and sieved to obtain pomegranate peel powder with a particle size of 100 mesh, and stored in a refrigerator at-20℃ for standby.

[0036] Example 1

[0037] Preparation of the deep eutectic solvent: anhydrous betaine, ethanolamine and water are stirred at 75℃ in a water bath for 3h until a colorless uniform transparent liquid is formed, heating is stopped, and the liquid is cooled to room temperature without crystal precipitation to present a stable state, thereby obtaining the deep eutectic solvent, wherein the molar ratio of anhydrous betaine to ethanolamine is 1:2.8, and the water content of the deep eutectic solvent is 18%(w / w);

[0038] Extraction of pomegranate peel polyphenols: the deep eutectic solvent and the pomegranate peel powder are mixed to maintain a solid-liquid ratio of 1g:45mL, then extracted at 30℃ in a water bath for 30min, and the supernatant is separated after centrifugation at 6000r / min for 8min to obtain the pomegranate peel polyphenol extract.

[0039] Example 2

[0040] The difference from Example 1 is that ethanolamine is replaced by ethylene glycol, and the molar ratio is replaced by 1:2. The others are the same as Example 1.

[0041] Example 3

[0042] The difference from Example 1 is that ethanolamine is replaced by 1,2-butanediol, and the molar ratio is replaced by 1:3. The others are the same as Example 1.

[0043] Example 4

[0044] The difference from Example 1 is that "the molar ratio of betaine anhydrous and ethanolamine is 1:2.8" is replaced by "the molar ratio of betaine anhydrous and ethanolamine is 1:2.7". The others are the same as Example 1.

[0045] Example 5

[0046] The difference from Example 1 is that "the molar ratio of betaine anhydrous and ethanolamine is 1:2.8" is replaced by "the molar ratio of betaine anhydrous and ethanolamine is 1:2.9". The others are the same as Example 1.

[0047] Example 6

[0048] The difference from Example 1 is that "the water content of the deep eutectic solvent is 18% (w / w)" is replaced by "the water content of the deep eutectic solvent is 14% (w / w)". The others are the same as Example 1.

[0049] Example 7

[0050] The difference from Example 1 is that "the water content of the deep eutectic solvent is 18% (w / w)" is replaced by "the water content of the deep eutectic solvent is 16% (w / w)". The others are the same as Example 1.

[0051] Example 8

[0052] The difference from Example 1 is that ultrasonic treatment is added in the extraction process of pomegranate polyphenols, that is, the extraction is carried out under the condition of 100W ultrasonic for 20min and 30℃ water bath for 30min.

[0053] Comparative Example 1

[0054] The difference from Example 1 is that betaine anhydrous is replaced by choline chloride, and the molar ratio is replaced by 1:3. The others are the same as Example 1.

[0055] Comparative Example 2

[0056] The difference from Example 1 is that ethanolamine is replaced by acetamide, and the molar ratio is replaced by 1:2. The others are the same as Example 1.

[0057] Comparative Example 3

[0058] The difference from Example 1 is that ethanolamine is replaced with 1,2-propanediol and the molar ratio is replaced with 1:3. Otherwise, it is the same as Example 1.

[0059] Comparative Example 4

[0060] The difference from Example 1 is that ethanolamine is replaced with propionic acid and the molar ratio is replaced with 1:2. Otherwise, it is the same as Example 1.

[0061] Comparative Example 5

[0062] The difference from Example 1 is that “the molar ratio of betaine anhydrous and ethanolamine is 1:2.8” is replaced with “the molar ratio of betaine anhydrous and ethanolamine is 1:3”. Otherwise, it is the same as Example 1.

[0063] Comparative Example 6

[0064] The difference from Example 1 is that “the molar ratio of betaine anhydrous and ethanolamine is 1:2.8” is replaced with “the molar ratio of betaine anhydrous and ethanolamine is 1:3.1”. Otherwise, it is the same as Example 1.

[0065] Comparative Example 7

[0066] The difference from Example 1 is that “the water content of the deep eutectic solvent is 18% (w / w)” is replaced with “the water content of the deep eutectic solvent is 12% (w / w)”. Otherwise, it is the same as Example 1.

[0067] Comparative Example 8

[0068] The difference from Example 1 is that “the water content of the deep eutectic solvent is 18% (w / w)” is replaced with “the water content of the deep eutectic solvent is 20% (w / w)”. Otherwise, it is the same as Example 1.

[0069] Comparative Example 9

[0070] The difference from Example 1 is that betaine anhydrous is replaced with choline chloride, ethanolamine is replaced with ethylene glycol, the molar ratio is replaced with 1:2, and the water content is replaced with 0% (w / w). Otherwise, it is the same as Example 1.

[0071] Comparative Example 10

[0072] The difference from Example 1 is that betaine anhydrous is replaced with choline chloride, ethanolamine is replaced with urea, the molar ratio is replaced with 1:2, and the water content is replaced with 30% (w / w). Otherwise, it is the same as Example 1.

[0073] Comparative Example 11

[0074] The difference from Example 1 is that betaine anhydrous is replaced with choline chloride, ethanolamine is replaced with glycerol, the molar ratio is replaced with 1:11, and the water content is replaced with 30% (w / w). Otherwise, it is the same as Example 1.

[0075] Comparative Example 12

[0076] The pomegranate peel powder was mixed with 50% ethanol at a solid-liquid ratio of 1 g:40 mL, stirred at 40°C for 60 min, and then centrifuged at 8000 r / min for 10 min. The supernatant was the pomegranate peel polyphenol extract.

[0077] Comparative Example 13

[0078] The pomegranate peel powder was mixed with a 30% (w / w) ethanol / 19% (w / w) ammonium sulfate aqueous two-phase system at a solid-liquid ratio of 1 g:40 mL, stirred at 40°C for 30 min, and then centrifuged at 8000 r / min for 5 min. The upper phase was the pomegranate peel polyphenol extract.

[0079] The above only describes the preferred embodiments of the present application. It should be noted that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of the present application.

Claims

1. A method of extracting polyphenols from Punica granatum L. pericarp using a betaine-based deep eutectic solvent, characterized by, The method comprises the following steps: (1) mixing a hydrogen bond acceptor solvent, a hydrogen bond donor solvent and water to obtain a eutectic solvent; (2) mixing the eutectic solvent and Punica granatum L. powder and then extracting, and then centrifuging to obtain a Punica granatum L. polyphenol extract; the hydrogen bond acceptor solvent is anhydrous betaine; and the hydrogen bond donor solvent is ethanolamine; a molar ratio of the hydrogen bond acceptor solvent to the hydrogen bond donor solvent is 1:2.7-3.1; and a water content of the eutectic solvent is 14-20% (w / w); a solid-liquid ratio of the Punica granatum L. powder to the eutectic solvent is 1g:40-55mL; in the step (2), an extraction temperature is 30-45℃, an extraction time is 20-90min, and an ultrasonic power is 80-120W; and a centrifugation speed is 5000-8000r / min, and a centrifugation time is 5-10min.

2. The method for extracting pomegranate peel polyphenols using a betaine-based eutectic solvent according to claim 1, characterized in that, in the step (1), a mixing temperature is 75-80℃, and a mixing time is 2-5h.

3. The method of claim 2, wherein the betaine-based deep eutectic solvent is selected from the group consisting of betaine, glycine, sarcosine, and derivatives thereof. after the mixing in the step (1), the obtained product is left to room temperature to obtain the eutectic solvent.

4. The method for extracting pomegranate peel polyphenols using a betaine-based eutectic solvent according to claim 3, characterized in that, a particle size of the Punica granatum L. powder is 80-200mesh.

5. The method for extracting pomegranate peel polyphenols using a betaine-based eutectic solvent according to claim 1, characterized in that, after the centrifugation in the step (2), the obtained supernatant is the Punica granatum L. polyphenol extract.

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