Abstract: The main goals of the current study were to optimize the ultrasonic-assisted extraction process for anthocyanins from purple potato, purify extracts using NKA-9 macroporous adsorption resin, and separate and identify anthocyanin constituents. The optimal conditions for anthocyanin extraction were found as follows: 2.5% citric acid aqueous solution as extraction solvent at a material-to-liquid ratio of 1:50 and 400 W ultrasonic power for an extraction duration of 10 min at 45 ℃. Under these conditions, the extraction yield of anthocyanins from purple potato was 1.362 mg/g (dry weight). Further, anthocyanins with 98.35% recovery and 90.23% purity were obtained after purification using NKA-9 macroporous adsorption resin as a result of elution with 8 bed volumes of pH 2.5, 55% ethanol aqueous solution containing citric acid. Using HPLC, 5 anthocyanin fractions were identified, including cy-3-glu, cy-3-rut and pn-3-glu with respective contents of 0.27, 0.057 and 0.46 mg/g sweet potato (dry weight), altogether accounting for 57.78% of total anthocyanins. The retention time of the most predominant anthocyanin was 12.224 min, while the structure was unknown.

Key words: purple potato, anthocyanin, ultrasonic, resin, HPLC