Abstract:

Purple sweet potato was used as the raw material to investigate the preparation processing of purple sweet potato beverage. The effects of sweet potato starch liquefaction by α-amylase and high temperature were compared, and then the starch was glycosylated by glucoamylase. The effect of treatment processing on anthocyanin was also explored on the basis of soluble solids, absorbance and color difference. Results indicated that the favorable hydrolysis of starch and the minimal loss of anthocyanin in purple sweet potato beverage could be achieved through following process: pulping of steamed sweet potato with water in double mass, then treating with 0.020 g/100mL α -amylase hydrolysis at 70 ℃ for 40 min, and followed by glycosylating with 0.04 g/100mL glucoamylase for hydrolysis at pH 5.0 for 40 min. An excellent beverage with attractive color, flavor and taste was developed by 30% purple sweet potato juice, 8% sucrose and 0.05% citric acid in soft water.

Key words: purple sweet potato, beverage, anthocyanin, α-amylase, glucoamylase