Study On Melanin From Black Sesame Cake With Supercritical Extraction And Its Activity

With the increasing emphasis on the safety of edible pigment, the development and utilization of natural pigments are also getting more and more attention. In the development of natural pigments, red, yellow, and green have more varieties than blue and black. Currently, BN and melanin of 1984 used in food are chemical synthesis of melanin. However, some countries of European Union have implemented rules to ban the use of the chemical synthesis of melanin. Therefore, the development of natural melanin has practical significance. Black sesame melanin（BSM） mainly exist in the testa of black sesame seed, it still present inside black sesame dregs（BSD） after pressing. Melanin extracted from BSD with Supercritical fluid not only can increase the source of the natural melanin and make better use of the BSD of material, but also would have less affect the BSD for secondary use for environment friendly extraction preocess.This paper is firstly study on the optimization of extracteing BSM from BSD with supercritical CO₂ and further purified and detection of bioactive function of extracting melanin. First, using extraction pressure, extraction temperature and CO₂ flow rate as the main factors of single factor experiments, on the basis of single factor experiments, choose suitable levels for each factor. Then, applying the response surface optimize process comditions of supercritical CO₂ extraction of BSM from BSD. The yield of BSM used as response values Y. After single factor experiments, determined the level of various factors: extraction pressure 10 to 18 MPa, extraction temperature 20 to 40 ℃, CO₂ flow rate 0.64 to 0.96 L/min. Using Box- Benbnken central composite design optimize extraction process, the optimized of extraction conditions: extraction pressure 14.31 MPa, extraction temperature 29.92 ℃ and CO₂ flow rate 0.75 L/min. The BSM extraction yield was 3.40% with the optimized conditions. Quadratic polynomial regression equation model fitting is good, could reflect the actual extraction. Then, Alkali solution and acid- isolation（ASAI）, silica gel column chromatography and AB-8 macroporous resin were used respectively to purify BSM with supercritical CO₂. PR（Purification rate） and CV（color value of pigment） were standard evaluation criteria of purification methods. With ASAI, column chromatography purification of of silica ge and AB-8 macroporous resin, the purification rate and color value of BSM were 1.06% and 305 1.02% and 278, respectively, and ASAI performed better than others.The activity researches of BSM mainly included two aspects: physical and chemical properties and antioxidant activity. The experiments results showed that the BSM with supercritical CO₂ extraction was soluble in alkaline solution, and temperature, salt, sugar, illumination, oxidant and reducing agent had less effects on stability of BSM, while pH show moer effects on stability of BSM than formers. The antioxidant activity mainly for in vivo and in vitro. In vitro part mainly through eliminating free radicals like ABTS +, hydroxyl and DPPH to evaluate the antioxidant capacity of BSM. Experimental results also show that BSM has the ability of removal of three kinds of free radicals, and the ability was improved with the increase of concentration of clearance rate. Besides, BSM performs better scavenging DPPD than other radicals, and the ability of removing hydroxyl radicals similar to Vc. The in vivo part, wild type yeast BY4741（WT） and its genetic defect type strains（SOD1△、CTT1â–³,GTT1â–³,GTT2△） were used as cell model, and the cell survival rate wsa used as the evaluation index. BSM were investigated respectively in the oxidative stress effect of yeast cell survival in the environment of Cd2+, CCl4, H2O₂. Then, using TBA（Thiobarbituri acid, associates） detect the membrane lipid peroxidation level of the five yeast cells under oxidative stress from Cd2+, CCl4 and H2O₂. Lastly, applying 2 ’7’- dichloro 2 acetate fluorescent probe method to determine effectson the fluorescence intensity of the five yeast cells under oxidative stress environment of Cd2+, CCl4, H2O₂. Through the above three methods to explore the antioxidant effect in vivo of BSM. The expweiments results show that the BSM can improve the tolerance of the five kinds of yeast cells, especially SOD1△和CTT1 â–³ showed better antioxidant.Oxidation of the experiments results showed that the BSM has good antioxidant capacity, and the antioxidant increased with the increase of concentration. BSM showed differenet antioxidant effect to different oxidative stress environment and the exist difference of yeast strains, especially SOD1△和 CTT1â–³.