Extraction methods affect the yield, purity, and composition of anthocyanins. This study was aimed to compare CE, UAE, and ASE as to the effectiveness of extraction of anthocyanins from purple sweet potatoes. While requiring high temp, ASE was a pressuredliquid and short-time extraction method and thus favored the extraction of anthocyanins that are heat labile from purple sweet potatoes. CE and UAE are long-time extraction methods at relatively low temperature and resulted in low anthocyanin yields with high impurities of other phenolics in this study. As far as the aspect of anthocyanin composition is concerned, ASE could extract more diacyl anthocyanins and less nonacyl and monoacyl
anthocyanins than CE or UEA, suggesting anthocyanins in ASE extracts were more stable than those extracted by CE or UAE. These methods also affected antioxidant activities of PSPs extracts. When applied to food matrix as antioxidant agents, PSPs anthocyaninrich extracts via the three methods demonstrated different activities depending on the mechanisms involved. CE and UAE extracts were more efficient in breaking radical chain activity while ASE
would be more suitable as an antioxidant via the mechanism of ferric reduction. The anthocyanin extraction method from PSP should take into consideration the extraction efficiency of bioactive compounds, antioxidant activities, and types of anthocyanins.