Method for extracting catechin from grape seeds by using natural eutectic solvent

Abstract

The invention discloses a method for extracting catechin from grape seeds by using a natural eutectic solvent, and relates to the technical field of food science and engineering.The method is technically characterized by comprising the steps that S1, raw material treatment is conducted, grape wine industry waste is collected and subjected to freeze-drying treatment to remove moisture, and then powder extraction raw materials are obtained through grinding treatment; the granularity of the powdery extraction raw material is 50-100 meshes; s2, preparing deep-eutectic solvents: mixing two natural deep-eutectic solvents in a molar ratio of 1: (1-2), and heating and stirring until a pure, transparent and uniform viscous liquid is formed; s3, mixing reaction: mixing the extraction raw material prepared in S1 and the eutectic solvent prepared in S2 to obtain a mixture; s4, ultrasonic treatment: performing ultrasonic treatment on the mixture obtained in S3 under a water bath condition; s5, solid-phase extraction and concentration: separating the mixture subjected to ultrasonic treatment in S4 by adopting a solid-phase extraction technology to obtain the grape seed polyphenol extract with catechin as a main component.

Description

Technical Field

[0001] The invention relates to the field of food science and engineering technology, and in particular to a method for extracting catechins from grape seeds by utilizing a natural low eutectic solvent. Background Art

[0002] my country is a major country in the global grape wine industry, and a large amount of grape wine waste is produced every year, including grape seeds, grape pomace, grape stems and grape leaves. These by-products are rich in grape seed polyphenol components such as catechins, which have good antioxidant and antibacterial potential. If they are directly discharged without reasonable treatment, they will have a negative impact on the environment. Therefore, extracting catechins from grape seed waste generated by the wine industry can not only meet the market demand for natural antioxidants, but also extend the Xinjiang wine industry chain, which has far-reaching significance for environmental protection and resource utilization.

[0003] At present, the main methods for extracting catechins include heating extraction, solvent extraction and ultrasonic extraction. Heating extraction is the most traditional method, which relies on increasing the temperature to increase the solubility of polyphenols; solvent extraction uses the principle of "like dissolves like" to extract the extract from the solvent. In recent years, ultrasonic extraction, as a new green extraction technology, has attracted attention due to its environmental protection, high extraction rate and low energy consumption. These methods have their own characteristics and are widely used.

[0004] The current methods for extracting catechins have achieved certain results in extracting catechins, but there are still some significant problems, such as: the extraction rate of heating extraction method is generally low, high temperature can easily destroy the biological activity of catechins; solvent extraction process may lead to solvent residues, increasing extraction costs. In addition, many traditional extraction methods have limited efficiency and are difficult to meet the market demand for high-purity natural antioxidants. Summary of the invention

[0005] The purpose of the present invention is to solve the above problems and provide a method for extracting catechins from grape seeds using a natural deep eutectic solvent. The natural deep eutectic solvent is a new type of extraction medium, an ionic liquid analog formed by interconnecting hydrogen bond donors and hydrogen bond acceptors, and its components such as sugars, organic acids, organic bases, amino acids and polyols are widely present in nature. This solvent has advantages that traditional organic solvents cannot match, such as high extraction rate, non-toxicity, low vapor pressure and high solubility. At the same time, ultrasonic extraction, as a new type of green extraction technology, has the advantages of environmental protection, high efficiency, low energy consumption and convenience for industrial production compared to traditional methods. Ultrasonic waves can destroy plant cell tissues through the "cavitation effect", remove mass transfer restrictions, and effectively extract target substances. Compared with conventional extraction, ultrasound-assisted natural deep eutectic solvent extraction significantly improves the extraction rate, and can enhance the contact between the solvent and the extraction matrix, reduce the diffusion boundary layer, and improve the extraction efficiency.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows: A method for extracting catechins from grape seeds using a natural deep eutectic solvent comprises the following steps:

[0007] S1. Raw material processing: collecting waste from the grape wine industry, removing its moisture through freeze-drying, and then grinding it to obtain powdered extraction raw materials;

[0008] The particle size of the powdered extraction raw material is 50-100 mesh;

[0009] S2. preparing a low eutectic solvent: selecting a mixture of two natural low eutectic solvents in a molar ratio of 1:1-2, heating and stirring until a pure, transparent, uniform viscous liquid is formed;

[0010] S3, mixing reaction: mixing the extraction raw material prepared in S1 and the low eutectic solvent prepared in S2 to obtain a mixture;

[0011] S4, ultrasonic treatment: subjecting the mixture obtained in S3 to ultrasonic treatment in a water bath;

[0012] S5. Solid phase extraction and concentration: The mixture after ultrasonic treatment in S4 is separated by solid phase extraction technology to obtain a grape seed polyphenol extract with catechins as the main component.

[0013] Preferably, the natural deep eutectic solvent comprises choline chloride, urea, glucose, glycerol and citric acid.

[0014] Preferably, in S1, the freeze-drying treatment includes a pre-freezing treatment and a vacuum freeze-drying treatment, the pre-freezing treatment conditions are -15°C to -45°C, the pre-freezing duration is 12-36h, the vacuum freeze-drying conditions are: -40°C to -80°C, and the vacuum freeze-drying duration is 24-48h.

[0015] Preferably, in S2, the low eutectic solvent is a mixture of two natural low eutectic solvents, choline chloride and citric acid, with a molar ratio of 1:1.2-2.0.

[0016] Preferably, in S3, the mixing ratio of the extraction raw material and the low eutectic solvent is 45-55 g / L by mass.

[0017] Preferably, in S4, the water bath temperature is 40-50°C, the ultrasonic time is 10-15 min, and the ultrasonic power is 200-300W.

[0018] The present invention also provides a method for preserving a grape seed polyphenol extract with catechin as a main component: preserving the extract in a natural low eutectic solvent composed of choline chloride and citric acid, wherein the choline chloride serves as a hydrogen bond acceptor and the citric acid serves as a hydrogen bond donor.

[0019] Compared with the prior art, this solution has the following beneficial effects:

[0020] Green and environmentally friendly: Using natural deep eutectic solvents as extraction media avoids the toxicity and environmental pollution problems of traditional organic solvents. Deep eutectic solvents are composed of natural materials, are biodegradable, and comply with the principles of green chemistry.

[0021] High extraction rate: Under the combined action of natural deep eutectic solvent and ultrasound, the extraction rate of catechins is significantly improved, which is much higher than that of traditional heating extraction and solvent extraction methods.

[0022] Protect biological activity: Ultrasonic extraction is performed under low temperature conditions, avoiding the decomposition and activity destruction of catechins by high temperature, and retaining their natural antioxidant capacity.

[0023] High product purity: After solid phase extraction, the catechins obtained are of high purity and have stronger antioxidant properties, meeting the market demand for natural and highly effective antioxidants. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the extraction rate of catechins by the extraction method of Example 1 of the present invention and the conventional extraction method;

[0025] Figure 2 is a comparison chart of catechin extraction contents by different extraction methods in Example 1 of the present invention;

[0026] Figure 3 is a schematic diagram of the effects of different extraction methods on the antioxidant capacity of catechin polyphenols in Example 1 of the present invention;

[0027] Figure 4 is a comparison chart of catechin extraction contents by different extraction methods in Example 2 of the present invention;

[0028] Figure 5 is a schematic diagram of the effects of different extraction methods on the antioxidant capacity of catechin polyphenols in Example 2 of the present invention;

[0029] Figure 6 is a comparison chart of catechin extraction contents by different extraction methods in Example 3 of the present invention;

[0030] Figure 7 is a schematic diagram of the effects of different extraction methods on the antioxidant capacity of catechin polyphenols in Example 3 of the present invention;

[0031] Figure 8 is a comparison chart of catechin extraction contents by different extraction methods in Example 4 of the present invention;

[0032] Fig. 9Schematic diagram of the effect of different extraction methods on the antioxidant capacity of catechin polyphenols in Example 4 of the present invention. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution of the present invention will be further described in detail below in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0034] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0035] Embodiment 1:

[0036] like Figure 1 As shown, a method for extracting catechins from grape seeds using a natural low eutectic solvent is provided, and the method can also improve the antioxidant activity of catechins. The specific steps are as follows:

[0037] Step 1: Pre-freeze the waste from the grape wine industry for 16 hours, freeze-dry it in a large-scale fruit and vegetable vacuum freeze dryer for 23 hours, grind it into powder and maintain its particle size at 60 mesh.

[0038] Step 2: Mix the hydrogen bond acceptor choline chloride and the hydrogen bond donor citric acid in a molar ratio of 1:1.6, and heat and stir until a pure, transparent, uniform viscous liquid is formed, and the viscosity is 187 mPa·S.

[0039] Step 3: Evenly mix the freeze-dried powder of the grape wine industry waste and the natural low eutectic solvent at a mass ratio of 48.3 g / L.

[0040] Step 4: Under water bath conditions, the mixture of freeze-dried powder of winemaking waste and natural low eutectic solvent was subjected to ultrasonic treatment at a temperature of 44° C., a time of 17 min, and a power of 285 W.

[0041] The specific steps of the conventional extraction method are as follows:

[0042] Step 1: Pre-freeze the waste from the grape wine industry for 16 hours, freeze-dry it in a large-scale fruit and vegetable vacuum freeze dryer for 23 hours, grind it into powder and maintain its particle size at 60 mesh.

[0043] Step 2: Evenly mix the freeze-dried powder of the grape wine industry waste with 85% ethanol solution at a mass ratio of 48.3 g / L.

[0044] Step 3: In a water bath, the mixture of freeze-dried powder of waste from grape winemaking industry and 85% ethanol solution was subjected to ultrasonic treatment at a temperature of 44° C., a time of 17 min, and a power of 285 W.

[0045] like Figure 2 and 3 As shown, through Figure 2 It can be seen that in this embodiment, the content of catechins obtained by the present extraction method is much higher than that by the conventional extraction method; Figure 3 It can be seen that the catechins obtained by this extraction method have stronger antioxidant capacity.

[0046] Embodiment 2:

[0047] A method for extracting catechins from grape seeds using a natural low eutectic solvent, and the method can also improve the antioxidant activity of catechins. The specific steps are as follows:

[0048] Step 1: Pre-freeze the waste from the grape wine industry for 17.5 hours, freeze-dry it in a large-scale fruit and vegetable vacuum freeze dryer for 23.5 hours, grind it into powder and maintain its particle size at 80.

[0049] Step 2: Mix the hydrogen bond acceptor choline chloride and the hydrogen bond donor citric acid in a molar ratio of 1:1.7, and heat and stir until a pure, transparent, uniform viscous liquid is formed, and the viscosity is 199 mPa·S.

[0050] Step 3: Evenly mix the freeze-dried powder of the grape wine industry waste and the natural low eutectic solvent at a mass ratio of 49.5 g / L.

[0051] Step 4: Under water bath conditions, the mixture of freeze-dried powder of winemaking waste and natural low eutectic solvent was subjected to ultrasonic treatment at 43.5° C., for 22 min, and with an ultrasonic power of 290 W.

[0052] The specific steps of the conventional extraction method are as follows:

[0053] Step 1: Pre-freeze the waste from the grape wine industry for 17.5 hours, freeze-dry it in a large-scale fruit and vegetable vacuum freeze dryer for 23.5 hours, grind it into powder and maintain its particle size at 80.

[0054] Step 2: Evenly mix the freeze-dried powder of the grape wine industry waste with 85% ethanol solution at a mass ratio of 48.3 g / L.

[0055] Step 3: Under water bath conditions, the mixture of freeze-dried powder of winemaking waste and 85% ethanol solution was subjected to ultrasonic treatment at a temperature of 43.5° C., a time of 22 min, and a power of 290 W.

[0056] like Figure 4 and 5 As shown, through Figure 4 It can be seen that in this embodiment, the content of catechins obtained by the present extraction method is much higher than that by the conventional extraction method; Figure 5 It can be seen that the catechins obtained by this extraction method have stronger antioxidant capacity.

[0057] Embodiment 3:

[0058] A method for extracting catechins from grape seeds using a natural low eutectic solvent, and the method can also improve the antioxidant activity of catechins. The specific steps are as follows:

[0059] Step 1: Pre-freeze the waste from the grape wine industry for 15.5 hours, freeze-dry it in a large-scale fruit and vegetable vacuum freeze dryer for 35.5 hours, grind it into powder and maintain its particle size at 88.3.

[0060] Step 2: Mix the hydrogen bond acceptor choline chloride and the hydrogen bond donor citric acid in a molar ratio of 1:1.7, and heat and stir until a pure, transparent, uniform viscous liquid is formed, and the viscosity is 185 mPa·S.

[0061] Step 3: Evenly mix the freeze-dried powder of the grape wine industry waste and the natural low eutectic solvent at a mass ratio of 53.5 g / L.

[0062] Step 4: Under water bath conditions, the mixture of freeze-dried powder of winemaking waste and natural low eutectic solvent was subjected to ultrasonic treatment at 44.8° C., for 18 min, and with an ultrasonic power of 260 W.

[0063] The specific steps of the conventional extraction method are as follows:

[0064] Step 1: Pre-freeze the waste from the grape wine industry for 15.5 hours, freeze-dry it in a large-scale fruit and vegetable vacuum freeze dryer for 35.5 hours, grind it into powder and maintain its particle size at 88.3.

[0065] Step 2: Evenly mix the freeze-dried powder of the grape wine industry waste with 85% ethanol solution at a mass ratio of 48.3 g / L.

[0066] Step 3: Under water bath conditions, the mixture of freeze-dried powder of waste from grape winemaking industry and 85% ethanol solution was subjected to ultrasonic treatment at 44.8° C., for 18 min, and with an ultrasonic power of 260 W.

[0067] like Figure 6 and 7 As shown, through Figure 6 It can be seen that in this embodiment, the content of catechins obtained by the present extraction method is much higher than that by the conventional extraction method; Figure 7It can be seen that the catechins obtained by this extraction method have stronger antioxidant capacity.

[0068] Embodiment 4:

[0069] A method for extracting catechins from grape seeds using a natural low eutectic solvent, and the method can also improve the antioxidant activity of catechins. The specific steps are as follows:

[0070] Step 1: Pre-freeze the waste from the grape wine industry for 20.5 hours, freeze-dry it in a large-scale fruit and vegetable vacuum freeze dryer for 32.5 hours, grind it into powder and maintain its particle size at 70.

[0071] Step 2: Mix the hydrogen bond acceptor choline chloride and the hydrogen bond donor citric acid in a molar ratio of 1:1.8, and heat and stir until a pure, transparent, uniform viscous liquid is formed, and the viscosity is 198 mPa·S.

[0072] Step 3: Evenly mix the freeze-dried powder of the grape wine industry waste and the natural low eutectic solvent at a mass ratio of 48.3 g / L.

[0073] Step 4: Under water bath conditions, the mixture of freeze-dried powder of winemaking waste and natural low eutectic solvent was subjected to ultrasonic treatment at 42.3° C., for 15 min, and with an ultrasonic power of 270 W.

[0074] The specific steps of the conventional extraction method are as follows:

[0075] Step 1: Pre-freeze the waste from the grape wine industry for 16 hours, freeze-dry it in a large-scale fruit and vegetable vacuum freeze dryer for 23 hours, grind it into powder and maintain its particle size at 60 mesh.

[0076] Step 2: Evenly mix the freeze-dried powder of the grape wine industry waste with 85% ethanol solution at a mass ratio of 48.3 g / L.

[0077] Step 3: Under water bath conditions, the mixture of freeze-dried powder of winemaking industrial waste and 85% ethanol solution was subjected to ultrasonic treatment at 42.3° C., for 15 min, and with an ultrasonic power of 270 W.

[0078] like Figure 8 and 9 As shown, through Figure 8 It can be seen that in this embodiment, the content of catechins obtained by the present extraction method is much higher than that by the conventional extraction method; Fig. 9 It can be seen that the catechins obtained by this extraction method have stronger antioxidant capacity.

[0079] The above specific embodiments are merely explanations of the present invention and are not limitations of the present invention. After reading this specification, those skilled in the art may make modifications to the embodiments without any creative contribution as needed. However, such modifications are protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for extracting catechins from grape seeds using a natural deep eutectic solvent, characterized in that: The following steps are involved: S1. Raw material processing: collecting waste from the grape wine industry, removing its moisture through freeze-drying, and then grinding it to obtain powdered extraction raw materials; The particle size of the powdered extraction raw material is 50-100 mesh; S2. preparing a low eutectic solvent: selecting a mixture of two natural low eutectic solvents in a molar ratio of 1:1-2, heating and stirring until a pure, transparent, uniform viscous liquid is formed; S3, mixing reaction: mixing the extraction raw material prepared in S1 and the low eutectic solvent prepared in S2 to obtain a mixture; S4, ultrasonic treatment: subjecting the mixture obtained in S3 to ultrasonic treatment in a water bath; S5. Solid phase extraction and concentration: The mixture after ultrasonic treatment in S4 is separated by solid phase extraction technology to obtain a grape seed polyphenol extract with catechins as the main component.

2. The method for extracting catechins from grape seeds using a natural deep eutectic solvent according to claim 1, characterized in that: The natural deep eutectic solvent includes choline chloride, urea, glucose, glycerol and citric acid.

3. The method for extracting catechins from grape seeds using a natural deep eutectic solvent according to claim 1, characterized in that: In S1, the freeze-drying process includes pre-freezing process and vacuum freeze-drying process. The pre-freezing process conditions are -15°C to -45°C, and the pre-freezing duration is 12-36h. The vacuum freeze-drying conditions are: -40°C to -80°C, and the vacuum freeze-drying duration is 24-48h.

4. The method for extracting catechins from grape seeds using a natural deep eutectic solvent according to claim 2, characterized in that: In S2, the low eutectic solvent is a mixture of two natural low eutectic solvents, choline chloride and citric acid, with a molar ratio of 1:1.2-2.

0.

5. The method for extracting catechins from grape seeds using a natural deep eutectic solvent according to claim 1, characterized in that: In S3, the mixing ratio of the extraction raw material and the low eutectic solvent is 45-55 g / L by mass.

6. The method for extracting catechins from grape seeds using a natural deep eutectic solvent according to claim 1, characterized in that: In S4, the water bath temperature is 40-50°C, the ultrasonic time is 10-15 min, and the ultrasonic power is 200-300W.

7. A grape seed polyphenol extract containing catechins as main components prepared by the method according to any one of claims 1 to 6, characterized in that: The grape seed polyphenol extract is stored in a natural low eutectic solvent consisting of choline chloride and citric acid, wherein the choline chloride serves as a hydrogen bond acceptor and the citric acid serves as a hydrogen bond donor.

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