Study On Processing Technology Of Purple Sweet Potato Wine And Its Antioxidant Activity

Purple Sweet Potato (PSP) is a new unique type of sweet potato varieties, in addition to the nutritional content of ordinary sweet potato, but also rich in anthocyanins and other bioactive substances. Fermented purple sweet potato wine(PSPW) and its antioxidant activity,phenolic acids and anthocyanins were studied in this dissertation. The main conclusions are as follows:1. Processing Technology of PSPW was identified. Purple sweet potato plasm : water = 1:1.5, The conditions of liquefaction and saccharification respectively use liquidα-amylase and glucoamylase optimum conditions, the response time respectively by 60min and 90min.Wine using Juice fermentation has a better taste than fermentation with Java, CICC No. 1383 of Saccharomyces cerevisiae strains is more suitable to ferment in purple sweet potato juice(PSPJ) than 1215, 1498. Through single factor and orthogonal trials, pH of yeast fermentation liquid and inoculum volume are the important factors, while temperature is secondary factor. Optimal conditions for fermentation are pH 3.8, yeast inoculum3%, fermentation temperature 18℃; aging temperature 10～12℃is more conducive to wine clarify and taste, 2～3 months are suitable.2. Purple sweet potato wine(PSPW)exhibited strong reducing capacity, DPPH radical scavenging acticity,inhibition of lipid peroxidation, but metal chelating activity was little. Antioxidant activities of PSPJ and PSPW were similar. Antioxidant capacity of PSPW (cooked sweet potato: water=1:1.5) are stronger than the dry red wine Under the same alcoholicity(about 11°).3. Ethyl acetate extract of PSPW were analyzed by high-performance liquid chromatography(HPLC). Five phenolic acids including chlorogenic acid,p-hydroxybenzoic acid,caffeic acid,ferulic acid and sinapic acid, were identified and quantified. Chlorogenic acid was most, while sinapic acid was second. Results indicated that antioxidant activities of PSPW were highly correlated with anthocyanins and total phenolic content. More chlorogenic acid and sinapic acid were high relevant, while less p-hydroxybenzoic acid,caffeic acid and ferulic acid were less relevant, even did not have the relevance, but their contribution to antioxidant capacity of PSPW can not be completely ignored. PSPW maded of Guangxi Hengxian PSP possibly contained anthocyanins, such as Pn-CafSop-Glc, Cy-CafPHBSop-Glc and Pn-CafPHBSop-Glc.