Abstract: The enzymatic hydrolysis of purple sweet potato was investigated for anthocyanin extraction. The effects of extraction temperature, pH, solid-to-solvent ratio, and enzyme amount on extraction rate of anthocyanins were explored by one-factor-at-a-time and orthogonal array design methods. The best extraction results were achieved by adding 0.25% α-amylase and 0.1% pectinase for hydrolysis at pH 5.5, 50 ℃, and a solid-to-solvent ratio of 1:15. The extract was adjusted to pH 2 and a concentration of 26.57 mg/100 mL for adsorption by AB-8 macro-porous resin at a flow rate of 1 mL/min and subsequent desoroption with 60% acidic ethanol solution at pH 3. Under these conditions, the extraction rate of anthocyanins was 2.71 mg/g, and the color value of the purified anthocyanins was 43.2.

Key words: purple sweet potato anthocyanins, enzymatic extraction, α-amylase, pectinase, macro-porous resins, purification