Comparative analysis of the contents of anthocyanins, starch, protein and constituents of anthocyanins in different varieties of purple sweet potato, PSP,(Ipomoea batatas(L.) Lam) was carried out and effects of processing and preservation methods on the content of anthocyanins were investigated, and then the extraction process parameters with acidified ethanol, supersonic assisted acidified ethanol and yeast fermentation were optimized. The stability to pH value, heat, light and metal ion and antio...