Extracted from pepper
Capsicum frutescence L., also known as pepper, hot pepper, spicy horn, and Qin pepper, is a plant of the genus Chrysosporium, and is one of the oldest crops planted by humans. The spicy ingredient in the pepper was first isolated from the pepper fruit by Thres in 1876 and was named capsaicin. Capsaicin is mainly formed in the vacuoles of the epidermal cells of the fetal placenta and is transported through the ovary septum to the vacuoles of the epidermal cells of the flesh. Capsaicin is a type of secondary metabolite produced by pepper. It is mainly derived from amino acids and is synthesized by a series of enzymes such as vanillinase and synthesizing enzyme. The aromatic amino acid phenylalanine is derived from the vanillyl amine moiety, and the proline or leucine is derived as a branched fatty acid moiety. Some phenolic precursors in the synthesis of capsaicin (eg, p-coumaric acid, phenylalanine, caffeic acid, 3-methoxy-4-hydroxycinnamic acid, vanillin, etc.) are also proteins and alkaloids. , flavonoids and synthetic precursors of lignin, so the synthesis of capsaicin and the synthesis of other substances have problems competing with common precursors.
Natural capsaicin is composed of a series of similar amide compounds, and the structure and properties of each family are extremely similar. According to its structure, it can be divided into: capsaicin family, dihydro capsaicin group, p-methyl capsaicin group, p-methyl capsaicinene chain group, p-methyl capsaicin saturated chain hydrocarbon group and p-phenylene pepper Alkali, each of which contains several components. The main components of capsaicin are capsaicin and dihydro capsaicin, according to their content: capsaicin about 69%, dihydro capsaicin about 22%, dihydrocapsaicin about 7%, high dihydro capsaicin about 1%, high capsaicin about 1%, in addition, also contains some very low content substances, such as decyl chloramine and octanoyl vanillylamine, which are all derivatives of o-methoxy phenol.
Method of extraction
Sodium hydroxide method
Using the principle that the phenolic hydroxyl group of capsaicin has weak acidity and can react with strong alkali, the reaction with capsaicin is carried out with sodium hydroxide solution as solvent, and the different amounts of lye, soaking time and soaking temperature are compared. The optimal process conditions were as follows: pepper extract: mass fraction 20% NaOH solution = 1 g: 9 mL, soaked at 80 ° C for 2 h. This method is simple and easy, but the operation time is low, the yield is not high, and the extraction rate under the optimal conditions is only 0.84%.
2. Ion exchange method
The crude capsaicinoid compound is prepared by dissolving sodium hydroxide, sodium sulfate, and n-hexane. The crude product is dissolved in sodium hydroxide for ion exchange, eluted with ethanol-ethyl acetate, concentrated, and crystallized. Further, capsaicin crystals having a purity of more than 98.5% were obtained in a yield of 0.6%.
3. Solvent extraction method
The solvent method is characterized in that the capsaicin is easily dissolved in an organic solvent such as acetone, ethanol, ethyl acetate, n-hexane or chloroform, and the pulverized pepper is leached in the single solvent or the mixed solvent, and the obtained leaching is performed. The liquid is distilled under reduced pressure and repeatedly extracted to obtain a crude method of capsaicin. It is the most mature and widely used biological active ingredient extraction method of the current technology and equipment. This method is widely used in the industry for large-scale production, but the purity of the extracted capsaicin is low, and the capsaicin having a capsaicin content of 6% to 10% is obtained, which is difficult to refine, and has high production cost and high loss.
If a solvent (such as ethanol, acetone, n-hexane, chloroform, petroleum ether or a mixture thereof) is directly extracted from the dried capsicum fruit, the resin is obtained, the extractant is recovered, and the pigment is separated from the component of the capsaicin by an extractant. Then, it is concentrated and crystallized to obtain a mixed crystal of the components of the pungent component, which is dissolved and further separated to obtain a fine product of the product.
4. Supercritical CO2 extraction
The supercritical CO2 extraction method is a new type of extraction and separation technology that utilizes the solubility of carbon dioxide in a supercritical state with a non-polar liquid solvent to separate, extract and refine the active ingredients. Supercritical CO2 extraction is carried out under conditions of less than 20 mesh, pressure of 20-30 MPa, temperature of 35-45 ° C, ethanol as solvent, extraction for 2 to 3 h, and the CO2 flow rate can be shortened to shorten the extraction time. Capsaicin with high purity and low impurities. This method has the advantages of relatively high extraction rate and purity, and no solvent residue, but the investment in disposable equipment is large, and it is not suitable for wide application in industrial production in China.
For example, the dried capsicum fruit is pulverized, placed in an extractor, and extracted with supercritical carbon dioxide at 85 ° C and a pressure of 166.72 × 105 Pa, and a mixture of the components of the pungent component can be directly obtained, and the extraction rate can reach 97%.
5. Enzymatic extraction
Capsaicin is present in the fibrous tissue of the capsicum powder. Using the highly specific reaction characteristics of the bio-enzyme, cellulase is used to decompose the cell wall and dissolve the capsaicin. Enzymatic extraction has been widely used in the extraction of plant active ingredients, but its requirements for temperature, pH and time of action are high, so it has certain limitations, suitable for laboratory research, and is not easy to mass produce.
6. Ultrasonic extraction
Using the vibration generated by the ultrasonic wave, the cell wall of the pepper is broken, and the release, diffusion and dissolution of the material in the pepper cell are accelerated, which is beneficial to the extraction of capsaicin. Compared with the traditional extraction method, it has the characteristics of simple operation, high extraction rate and less time.
7. Microwave extraction
Microwave extraction refers to a method of successfully extracting active ingredients by using high-frequency electromagnetic wave penetration technology to increase the internal temperature of the cells, increase the pressure, and cause the cells to rupture. Compared with conventional techniques, the microwave method can produce higher extraction efficiency at lower temperatures, but this method is only suitable for laboratory research and is difficult to industrialize.
8. Micro-cut assisted technology assisted extraction
Micro-cutting and mutual-assisting technology is a new application in the field of mechanochemistry. It refers to the use of mechanochemical effects to grind plant raw materials and chemical additives to achieve super-crushing state. As an extraction pretreatment, water or dilute alcohol is used to extract active ingredients. a technology. The basic principle of the technology is that after the pulverization process, the plant cell wall is broken, and a chemical reaction occurs between the chemical auxiliary and the effective active ingredient, thereby improving the extraction efficiency and the water solubility and availability of the effective active ingredient. This technology has the advantages of energy saving and environmental protection, reducing costs, and improving extraction rate.
9. Biological methods
Biological methods include both biological and biosynthetic methods. For example, the pepper seeds are first aseptically treated, and then germinated in a Zan's dish for about 7 days, then the axillary bud cells are mixed with sodium alginate, and calcium nitride is used as a fortifier to embed the immobilized cells. The granules are finally cultured in a medium containing nutrients, and the content of capsaicin is increased to 13 times the original content. At present, the synthesis of biological methods has not achieved the expected results and needs further investigation.
10. Chemical synthesis
From the chemical structure analysis, capsaicin is an amide compound composed of a fatty acid and vanillyl amine, and thus can be synthesized by reverse synthesis. For example, the method of synthesizing capsaicin by using five-step reaction of isobutyl zinc and 1,6-hexanedicarboxylic acid monoethyl ester chloride has become a classic of capsaicin synthesis.