Extracion, Purification, Structural Identification And Stability Of Black Soybean Red Anthocyanins

With black bean skin as raw material, this paper discussed the extraction process of black soybean anthocyanins by ethanol, then the extraction process, purification method and physical properties, constitute and structure of anthocyanins were studied. At the same time, we also had researched the stability of anthocyanins in different conditions. All this done is for providing theoretical basis for the future of black soybean anthocyanins products.The optimum extraction technology parameters determined by ethanol were as follows:70% ethanol, pH value 1.0, material-solvent ratio 1:40, extraction time 1.5 h, extraction temperature 50? and extracted once. Anthocyanins content was 7.20 mg/g.Black soybean anthocyanins extracts after extracting by petroleum ether, and then purified by AB-8 resin, the absorption rate was 76.27%, analysis rate was 42.38%. The optimal absorbance of anthocyanins was 1.500, flow rate was 2 mL/min, pH value was 3.0.Meanwhile AB-8 had the best desorption effect when the concentration of ethanol was 60%,and the flow rate was 1 mL/min. The yield of anthocyanins was 9.12%, recovery rate was 84.13% after purification. Black soybean anthocyanins could be greatly refined by AB-8,the color scale of anthocyanins was 37.44. The main components of black soybean anthocyanins were Cyanidin-3-glucoside or Procyanidin-3-galactoside.Black soybean anthocyanins stability results show that, the anthocyanins stability was stable under pH 3.0, and black soybean anthocyanins was sensitive to light and high temperature. At the same time,ascorbic acid, oxidizer H2O2 and reductive Na2SO3 could decrease the stability of anthocyanins. Sucrose, glucose and food additives on the stability of anthocyanins no adverse effect, as well as Na+,Mg2+.Cu2+,Fe2+ ,Al3+,Fe3+ had a great influence on stability of anthocyanins, Zn2+,Ca2+ could add color and stability of anthocyanins. In addition, High temperature, high pressure and ultraviolet radiation were harmful to the stability of anthocyanins.The study results of effect of organic acids on stability of anthocyanins proved that:after adding oxalic acid, maleic acid, Malonic acid and tartaric acid, the anthocyanins'biggest absorbance increased, and the maximum absorption wavelength red shift. Besides,the half-lives(T1/2) and activity energy(Ea) were increased. The stability of anthocyanins was increased under high temperature and light conditions. During the copigmention, there was no anthocyanins derivatives were formed, it was proved that non-covalent copigmentation happened between Organic acids and black soybean anthocyanins.In order to improve the stability of anthocyanins, the molecular modification of the purified anthocyanins from black bean peel by copigmentation, etherification, acylation and esterification, and then the light, thermal stability and the scavenging effects on DPPH of modified anthocyanins was studied. The results showed that, after being heated at 90 ?for 5 h,the preservation rate of anthocyanins by copigmentation, acylation and etherification increased 17.88%, 16.75%, 5.46%, respectively.Under the sunlight irradiation for 8 d, the preservation rate of anthocyanins by copigmention, acylatation, etherification and esterification increased 25.27%, 20.86%, 20.19%, 13.83%, respectively. Besides, the scavenging rate on DPPH of modified anthocyanins is more than 95%, that is the same as Vc.