Determination of Anthocyanins Content in Purple Sweet Potato and in Purple Sweet Potato Sake and Study on Its Stability

The change of anthocyanin content in purple sweet potato and in purple sweet potato sake and the stability of anthocyanin were investigated by use of pH-differential method.The results showed that the best extraction conditions of anthocyanin were as follows: the ratio of raw materials and liquid was 1∶15,HCl concentration was 0.4 mol/L,the extraction temperature was at 50 ℃,and the extraction time was 2 h.Anthocyanin had good stability to light,temperature,acids,and alkaline,however,oxygen had great influence on its stability.Accordingly,purple sweet potato sake should better be stored in low-temperature,oxygen-absence,and dark places.