Method for extracting and purifying pericarp anthocyanin
Through the traditional extraction method and membrane filtration method combined with the use of aqueous acid solution and citric acid, the problems of structural instability and high cost in anthocyanin extraction are solved, and the high color price, solubility and stability of liquid anthocyanin are improved, and the simplification of the simplification of the simplification of the simplification of the simplification of the simplification of the simplification of the simplification of the simplification of the simplification of the The process and reduce production costs.
Patent Information
- Application Number
- CN202311758765.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-20
- Publication Date
- 2024-12-13
AI Technical Summary
In the prior art, the anthocyanin extraction method has problems such as unstable structure, high cost, expensive equipment, destruction of glycosidic bonds and generation of impurities, resulting in low product color price, poor solubility and poor stability.
The traditional leaching method was used to combine acid aqueous solution and food-grade citric acid as extraction solvent, and purified by membrane filtration, and pH adjustment and concentration under vacuum to obtain liquid anthocyanin products.
It improves the color price, solubility and stability of liquid anthocyanins, reduces production costs and impurity residues, simplifies process steps, improves the safety of the product and complies with national standards.
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Figure CN119119141A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of natural pigment extraction, in particular to a method for extracting and purifying anthocyanins from peel. Background Art
[0002] Anthocyanin is a flavonoid polyphenol compound formed by the glycosidic bond between anthocyanidin and sugar. As a secondary metabolite of plants, it is widely present in nature. It is a safe natural pigment with significant antioxidant capacity and excellent nutritional activity. It has multiple physiological functions such as anti-free radical, prevention of cardiovascular disease, and anti-tumor. It has broad application prospects in the fields of medicine, food, and cosmetics.
[0003] With the development of science and technology, the extraction methods of anthocyanins have also made considerable progress, but there is still room for improvement: ultrasound-assisted extraction may cause changes in the structure of anthocyanins, affecting their stability; microwave-assisted extraction is only suitable for extracting components with good thermal stability; enzyme extraction is costly and may destroy the glycosidic bonds of anthocyanins and produce impurities; the equipment and instruments required for supercritical fluid extraction are expensive and time-consuming, and the production cost is too high, making it unsuitable for industrial production. In summary, designing an anthocyanin extraction and purification method with simple and efficient process steps that helps to improve the color value, solubility and stability of liquid anthocyanin products has become a research and development direction that needs to be urgently addressed by technicians in this field. Summary of the invention
[0004] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a method for extracting and purifying anthocyanins from peels, which can effectively improve the color value and solubility of liquid anthocyanin products and solve the problems of weak coloring power of the products and precipitation of precipitation during long-term storage.
[0005] The present invention is achieved through the following technical solutions:
[0006] A method for extracting and purifying anthocyanins from peel, comprising the following steps:
[0007] S1. The dried peel is placed in an extraction tank as a raw material, and an extraction solvent is added for extraction, wherein the extraction solvent comprises an aqueous acid solution and food-grade citric acid to obtain a crude anthocyanin extract;
[0008] S2. Purifying the crude anthocyanin extract by membrane filtration to obtain anthocyanin extract;
[0009] S3. The pH value of the anthocyanin extract is adjusted and vacuum concentrated to obtain a liquid anthocyanin product.
[0010] According to the above technical solution, preferably, in step S1, the amount of the acid aqueous solution added is 6-9 times the mass of the raw material, and the acid aqueous solution is preferably a sodium metabisulfite aqueous solution with a pH range of 4-5.
[0011] According to the above technical solution, preferably, in step S1, after adding the acid aqueous solution into the extraction tank, the pH of the extraction solvent is adjusted to 2-3 by adding the food-grade citric acid.
[0012] According to the above technical solution, preferably, in step S1, the extraction temperature is 50-70°C and the extraction time is 2-3h.
[0013] According to the above technical solution, preferably, in step S2, the anthocyanin crude extract is purified by hollow fiber membrane filtration.
[0014] According to the above technical solution, preferably, in step S3, the pH of the anthocyanin extract is adjusted to 2-4, and vacuum concentrated at a temperature range of 60-75° C. to obtain a liquid anthocyanin product.
[0015] According to the above technical solution, preferably, in step S1, the "dried grape skin" includes dried grape skin that has been dried.
[0016] The beneficial effects of the present invention are:
[0017] The invention adopts the traditional leaching method for extraction, which can reduce the loss of anthocyanin in the subsequent processing process. At the same time, the acid aqueous solution of sodium pyrosulfite is selected as the extraction solvent, the addition amount is small, no organic solvent is used, no toxic substance remains, and the production safety is greatly improved; food-grade citric acid is added to the extraction solvent, which reduces the loss of anthocyanin in the subsequent production process and improves the color value and solubility of the liquid anthocyanin product; in addition, during purification, only hollow fiber membrane filtration is used to obtain a refined extract, the process is simple, impurities and residual sulfur dioxide can be efficiently removed, and the product meets the national standard requirements. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is a comparison chart of various test results of anthocyanins in Examples 1-3 of the present invention and Comparative Examples 1-4. DETAILED DESCRIPTION
[0019] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and the best embodiment. Based on the embodiments in the invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the invention.
[0020] The present invention comprises the following steps:
[0021] S1. Place the dried grape peel (preferably the dried grape peel) as the raw material in an extraction tank, add the extraction solvent for extraction, the extraction temperature is 50-70°C, the extraction time is 2-3h, and the anthocyanin crude extract is obtained. The extraction solvent includes an acid aqueous solution and food-grade citric acid. In this example, the acid aqueous solution is preferably, but not limited to, a sodium pyrosulfite aqueous solution (pH range of 4-5). In the extraction tank, an acid aqueous solution 6-9 times the mass of the raw material is added as the extraction solvent, and then the pH of the extraction solvent is adjusted to 2-3 by adding food-grade citric acid.
[0022] S2. Purify the crude anthocyanin extract by membrane filtration (hollow fiber membrane) to obtain anthocyanin refined extract.
[0023] S3. The pH of the anthocyanin extract is adjusted to 2-4, and vacuum concentrated at a temperature range of 60-75° C. to obtain a liquid anthocyanin product.
[0024] As a traditional extraction method, solution extraction has the advantage of low cost and is in line with the current production level of enterprises. Anthocyanin, as a polar molecule, is a water-soluble pigment that is easily soluble in water. Sodium metabisulfite is a common color preservative that can work together with citric acid to have an antioxidant effect. It can protect anthocyanin during the extraction and purification process and prevent its inactivation.
[0025] Membrane separation technology is an emerging high-tech technology that uses the different molecular weights of the components in the mixture to separate the components and purify and remove impurities through membranes of different pore sizes. Using it in the purification stage of anthocyanins is conducive to the rapid and efficient separation of impurities in the crude extract, purification of anthocyanins, and keeping anthocyanins in a state of high purity and high stability. The membrane separation method is simple to operate and has a wide range of applications. It can improve product quality and help solve major problems currently facing mankind, such as energy, resources, and the environment.
[0026] The technical effects of the method for extracting and purifying anthocyanins from peel disclosed in the present application are characterized by the following Examples 1-3 and Comparative Examples 1-4.
[0027] Embodiment 1:
[0028] Extraction: put the raw materials into the extraction tank, add 8 times acid aqueous solution to make the pH of the acid aqueous solution = 4.7, then add food grade citric acid to the acid aqueous solution to make the extraction solvent pH = 2.2, set the extraction time to 2h, the extraction temperature to 50℃, and perform extraction.
[0029] Purification: After the crude extract was allowed to stand for a period of time, it was purified by hollow fiber membrane and the pH of the anthocyanin extract was adjusted to 3.
[0030] Concentration: Transfer the anthocyanin extract to a rotary evaporator, set the temperature to 60°C, concentrate, and remove excess water to obtain a liquid anthocyanin product.
[0031] Embodiment 2:
[0032] Extraction: put the raw materials into the extraction tank, add 8 times acid aqueous solution to make the pH of the acid aqueous solution = 4.7, then add food grade citric acid to the acid aqueous solution to make the extraction solvent pH = 2.2, set the extraction time to 2.5h, the extraction temperature to 60℃, and perform extraction.
[0033] Purification: After the crude extract was allowed to stand for a period of time, it was purified by hollow fiber membrane and the pH of the anthocyanin extract was adjusted to 3.
[0034] Concentration: Transfer the anthocyanin extract to a rotary evaporator, set the temperature to 65°C, concentrate, and remove excess water to obtain a liquid anthocyanin product.
[0035] Embodiment 3:
[0036] Extraction: put the raw materials into the extraction tank, add 6 times acid aqueous solution to make the pH of the acid aqueous solution = 4.7, then add food grade citric acid to the acid aqueous solution to make the extraction solvent pH = 2.2, set the extraction time to 3h, the extraction temperature to 70℃, and perform extraction.
[0037] Purification: After the crude extract was allowed to stand for a period of time, it was purified by hollow fiber membrane and the pH of the anthocyanin extract was adjusted to 3.
[0038] Concentration: Transfer the anthocyanin extract to a rotary evaporator, set the temperature to 70°C, concentrate, and remove excess water to obtain a liquid anthocyanin product.
[0039] Comparative Example 1:
[0040] Extraction: put the raw materials into the extraction tank, use 8 times 50% methanol solution as the extraction solvent, then add food grade citric acid to the extraction solvent to make the pH of the extraction solvent = 3.5, set the extraction time to 2h, the extraction temperature to 50°C, and perform extraction.
[0041] Purification: After the crude extract was allowed to stand for a period of time, it was purified by hollow fiber membrane and the pH of the anthocyanin extract was adjusted to 3.
[0042] Concentration: Transfer the anthocyanin extract to a rotary evaporator, set the temperature to 60°C, concentrate, and remove excess water to obtain a liquid anthocyanin product.
[0043] Comparative Example 2:
[0044] Extraction: put the raw materials into the extraction tank, use 8 times 50% ethanol solution as the extraction solvent, then add food grade citric acid to the extraction solvent to make the pH of the extraction solvent = 3.5, set the extraction time to 2h, the extraction temperature to 50°C, and perform extraction.
[0045] Purification: After the crude extract was allowed to stand for a period of time, it was purified by hollow fiber membrane and the pH of the anthocyanin extract was adjusted to 3.
[0046] Concentration: Transfer the anthocyanin extract to a rotary evaporator, set the temperature to 60°C, concentrate, and remove excess water to obtain a liquid anthocyanin product.
[0047] Comparative Example 3:
[0048] Extraction: put the raw materials into an extraction tank, add 8 times acid aqueous solution to make the pH of the acid aqueous solution = 4.7, set the extraction time to 2h, the extraction temperature to 50°C, and perform extraction.
[0049] Purification: After the crude extract was allowed to stand for a period of time, it was purified by hollow fiber membrane and the pH of the anthocyanin extract was adjusted to 3.
[0050] Concentration: Transfer the anthocyanin extract to a rotary evaporator, set the temperature to 60°C, concentrate, and remove excess water to obtain a liquid anthocyanin product.
[0051] Comparative Example 4:
[0052] Extraction: put the raw materials into the extraction tank, add 8 times acid aqueous solution to make the pH of the acid aqueous solution = 4.7, then add food grade citric acid to the acid aqueous solution to make the extraction solvent pH = 2.2, set the extraction time to 2h, the extraction temperature to 50℃, and perform extraction.
[0053] Purification: After the crude extract is allowed to stand for a period of time, it is purified by suction filtration through filter paper, and the pH of the anthocyanin extract is adjusted to 3.
[0054] Concentration: Transfer the anthocyanin extract to a rotary evaporator, set the temperature to 60°C, concentrate, and remove excess water to obtain a liquid anthocyanin product.
[0055] The obtained liquid anthocyanin is tested for anthocyanin content, color value, and sulfur dioxide residue according to the method of GB 28313-2012, and stored at 4°C in the dark for one week to observe its dissolution. According to actual needs, the color value should be greater than 3, the anthocyanin content should be greater than 80%, the sulfur dioxide residue should comply with GB 28313-2012, and the product should not precipitate after being stored for one week.
[0056] Comparison of the test results of anthocyanins in Examples 1-3 and Comparative Examples 1-4 Figure 1As shown. Color value is one of the important indicators to measure the coloring ability and pigment content of natural pigments. This method can improve the color value of grape skin anthocyanins, thereby improving their coloring ability. Grape skin anthocyanins are prone to precipitation after being stored for a period of time, and have poor stability. At present, the national standard "GB28313-2012 Grape Skin Red" does not stipulate the solubility of anthocyanins. This method can improve the solubility of anthocyanins in the solution system, so that it can be stored for a long time without precipitation, and improve the stability of liquid anthocyanins.
[0057] Compared with Comparative Example 1 (methanol solution as extraction solvent) and Comparative Example 2 (ethanol solution as extraction solvent), the liquid anthocyanin samples prepared by extraction of Examples 1-3 and Comparative Examples 2-3 (acid aqueous solution as extraction solvent) have higher anthocyanin content. Compared with methanol and ethanol, acid water has higher extraction efficiency for anthocyanin, and no organic solvent is required, and the production is safe and pollution-free. Methanol is highly toxic and is not suitable for anthocyanin extraction. The production cost and production safety of ethanol solution extraction are higher than those of acid aqueous solution extraction. Extracting anthocyanin with color preservative aqueous solution as extraction solvent can protect anthocyanin and reduce its oxidation degree, and the amount added is small, no pollution will be generated, and it is more suitable for actual production of enterprises.
[0058] Further comparison of the liquid anthocyanin samples extracted and prepared by Examples 1-3 and Comparative Examples 2 and 4 (adding citric acid) compared to Comparative Example 2 (not adding citric acid) showed a higher color value, indicating that citric acid protected anthocyanins and reduced losses during subsequent processing.
[0059] Comparing Examples 1-3 and Comparative Examples 2-3 (hollow fiber membrane purification), the liquid anthocyanin samples extracted and prepared by Comparative Example 4 (filter paper filtration purification) have lower residual sulfur dioxide, indicating that the ability of the hollow fiber membrane to remove impurities is significantly stronger than that of filter paper filtration, and the crude anthocyanin extract is not suitable for filtration. In comparison, the hollow fiber membrane purification operation is more convenient and can save the human resources required for production.
[0060] Finally, by comparing Examples 1-3 and Comparative Example 2 (adding citric acid and hollow fiber membrane purification) with Comparative Example 3 (not adding citric acid) and Comparative Example 4 (filter paper filtration purification), the obtained liquid anthocyanin samples have higher solubility and no precipitation occurs after long-term storage, indicating that the antioxidant property of citric acid protects anthocyanins and slows down their degradation, and the purification by hollow fiber membrane improves the purity of anthocyanins, and the two together improve the stability and solubility of anthocyanin products.
[0061] The invention uses dried grape skins that have been aired as raw materials, changes the extraction solvent composition during extraction, combines a color retaining agent with citric acid as an extraction solvent, reduces the degree of anthocyanin oxidation, does not contain any organic solvents during the extraction process, has no harmful substance residues, and is safe and pollution-free. During purification, only hollow fiber membrane filtration is used to remove impurities and sulfur dioxide to obtain a refined extract, and no other purification steps are required, which simplifies the operating steps of the production process, reduces the loss of anthocyanins in subsequent processing, and improves the color value and solubility of anthocyanins, thereby solving the problem that liquid anthocyanins have poor coloring power and precipitation will occur during long-term storage.
[0062] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for extracting and purifying anthocyanins from peel, characterized in that: The steps include: S1. The dried peel was placed in an extraction tank as a raw material and an extraction solvent was added for extraction. The extraction solvent included an aqueous acid solution and food-grade citric acid to obtain a crude anthocyanin extract; S2. The crude anthocyanin extract was purified by membrane filtration to obtain anthocyanin extract; S3. Adjusting the pH of the anthocyanin extract and concentrating it in vacuo to obtain a liquid anthocyanin product.
2. The method for extracting and purifying anthocyanins from peel according to claim 1, wherein: In step S1, the amount of the acid aqueous solution added is 6-9 times the mass of the raw material.
3. A method for extracting and purifying anthocyanins from peel according to claim 2, characterized in that: In step S1, the acid aqueous solution is a sodium metabisulfite aqueous solution, and its pH range is 4-5.
4. A method for extracting and purifying anthocyanins from peel according to claim 3, characterized in that: In step S1, after adding the acid aqueous solution into the extraction tank, the pH of the extraction solvent is adjusted to 2-3 by adding the food-grade citric acid.
5. A method for extracting and purifying anthocyanins from peel according to claim 4, characterized in that: In step S1, the extraction temperature is 50-70° C., and the extraction time is 2-3 hours.
6. The method for extracting and purifying anthocyanins from peel according to claim 1, wherein: In step S2, the anthocyanin crude extract is purified by filtration using a hollow fiber membrane.
7. The method for extracting and purifying anthocyanins from peel according to claim 1, wherein: In step S3, the pH of the anthocyanin extract is adjusted to 2-4, and vacuum concentrated at a temperature range of 60-75° C. to obtain a liquid anthocyanin product.
8. The method for extracting and purifying anthocyanins from peel according to any one of claims 1 to 7, characterized in that: In step S1, the "dried grape peel" includes dried grape peel that has been dried.