Study On The Extraction And Purification,Stability And Application Of Anthocyanin From Purple Sweet Potato

Purple sweet potato is annual herb convolvulaceae. Anthocyanin which is rich in them has nutrition and health function, etc. Therefore, anthocyanin is natural pigment that has extremely developed valuable. Selected the Hainan purple sweet potato as the research object in this paper. Study preliminary on the extraction, purification process, stability and application of the anthocyanin that extracted from the purple sweet potato.The optimum parameters of purple sweet potato anthocyanin extraction by single factor and response surface experimental design: the extraction temperature was 70℃, the extraction concentration was 80%, the extract pH was 1.0, the solid-liquid ratio was 1:15.The crude extraction of anthocyanin was purified by macroporous resin. The macroporous resin was basically saturated after two hours static adsorption of purple sweet potato anthocyanin. The pH value of analytical solution within the range of 1.0-3.0 had no significant effect to the adsorption capacity of macroporous resin. The concentration of ethanol desorption liquid would affect the desorption. The solution of 80% ethanol that contained 1% hydrochloric acid had a relatively good desorption, the elution volume was 200mL, the color value of purified purple sweet potato anthocyanin was 49.9.The purple sweet potato anthocyanin was water-soluble pigment, It showed stability of red-purple under acidic conditions and poor stability of blue-green under alkaline conditions. The purple sweet potato anthocyanin had strong resistance of thermal, it had good stability under 60℃, the preservation rate decreased above 80℃, the best stability of anthocyanins was kept from light. Food preservatives had no effect on the stability of purple sweet potato anthocyanins; glucose and sucrose had a certain color-protecting effect on purple sweet potato anthocyanin; Vc had effects on purple sweet potato anthocyanin obviously; H₂O₂, Cu²⁺, Fe²⁺ had a greater impact on the stability of purple sweet potato anthocyanin. The solution of anthocyanin would become turbid with the effect of Cu²⁺and Fe²⁺.Purple sweet potato anthocyanin was a good beverage additives that had colors of bright and nature, determined the optimal ratio of Hawthorn juice by orthogonal experimental design: juice content was 40%, citric acid was 0.1% , sucrose was 12%, anthocyanins was 0.007%, the beverages had rich flavor and bright color. Purple sweet potato anthocyanin had a certain inhibitory effect on Human pathogenic bacteria of E.coli, S.aureus and P.aeruginosa, the minimum inhibitory concentration was 800μg/mL, 400μg/mL and 1600μg/mL.