Technical Study About The Anthocyanins Content Of Purple Sweet Potato Wine

Purple sweet potato wine is a kind of pure grain fermented low-alcohol wines used purple sweet potatoes as the main raw material. It has good resistance to oxidation, and it can prevent cardiovascular disease, hyperglycemia, hyperlipidemia, cancer and other diseases as a high health-care value. This research established a pH differential method for anthocyanin content of purple sweet potato wine, and optimized the testing conditions. This research established a MaiQu-pectinase fermentation method of purple sweet potato wine, and fermentation conditions were optimized. The researchers compared the antioxidant properties of purple potato wine and the storage conditions were analyzed.The testing conditions of pH differential method for the anthocyanin content of the purple sweet potato wine was optimized as the optimal wavelength 526nm, measured pH value of pH1 and pH4.5,20℃ of the equilibrium temperature, the equilibrium time of 110min.With purple sweet potato as raw materials, the traditional method of MaiQu fermentation technology and modern methods of enzymatic fermentation process was combined as MaiQu-pectinase fermentation method using MaiQu scarification and fermentation process with pectinase added. Optimized by single factor experiment and Box-Behnken response surface model equation, the researchers predicted the optimal fermentation parameters for temperature 19.5℃, water ratio of 1:0.5, the amount of pectinase added 10U/g,0.16% yeast added, MaiQu added the amount of 18%, and the researchers did experiment to verify the optimum fermentation conditions. Under this condition, purple sweet potato wine was fermented with the anthocyanin content of 276.5mg/L, reached the end of fermentation time of 18 days compared with the 30 days of traditional method, the sensory evaluation outstanding.With MaiQu-Pectinase Fermentation, the anthocyanin content of purple sweet potato wine reached 276.5mg/L, and the total phenolic content was 2369.6mg/L, with a reducing power absorbance value of 0.971, a DPPH · radical scavenging rate of 85.2%. It had good oxidation resistance which was superior to commercial purple potato wine and commercial red wine.While the purple sweet potato wine was processed under temperature 4℃ for 8h, the anthocyanin content of saving was 98.9%. When the temperature exceeded 30℃, it declined rapidly. When it was processed 8h under 50℃, the anthocyanin content of was 60.9%. After 24d stored under natural light and fluorescent light, the anthocyanin content saving rate of purple sweet potato wine was 42.8% and 16.9%, respectively. When stored in a dark environment for 24d, the anthocyanin content saving rate of purple sweet potato wine was 79.7%. This showed that purple sweet potato wine storage need low, dark environment, and the storage temperature should not exceed 30℃, and it should not be heated while drinking. Purple sweet potato wine should be packed in dark glass bottles or opaque porcelain.