Abstract: The antioxidant activities and anthocyanin composition of purple sweet potatoes from nine varieties cultivated in Guangdong were determined. The results indicated that total phenolic contents and antioxidant activities of different varieties were different. The total phenolic content of Guangzi 9 was 578 mg GAE/100 g fresh weight, and the 2,2’-amino-di (3-ethyl-benzothiazoline sulphonic acid-6) ammonium salt (ABTS+·) radical scavenging activity, oxygen radical absorbance capacity, and reducing power were 4.36, 10.38, and 11.23 μmol TE/g fresh weight, respectively, which were superior to those of the other varieties. Sixteen anthocyanins, including 8 cyanidins and 8 peonidins, were identified by high performance liquid chromatography-quadrupole-time of flight mass spectrometry (HPLC-QTOF-MS). The content of total anthocyanins was in the range of 77.17–1 125.06 mg/kg fresh weight, and Guangzi 9 showed the highest anthocyanin content. Acylated anthocyanins were the main anthocyanin constituents in purple sweet potatoes. Acylated anthocyanins were 89 times more abundant than non-acylated ones in Guangzi 9, which showed a significantly higher content of acylated anthocyanins than the other varieties. Taken together, the antioxidant activities and anthocyanin composition of different purple sweet potato varieties were different with Guangzi 9 exhibiting the highest content of anthocyanins and highest antioxidant capacity.

Key words: purple-fleshed sweet potato, antioxidant activity, anthocyanins, identification, quantitation