An analytical pipeline to compare and characterise the anthocyanin antioxidant activities of purple sweet potato cultivars

•Thirty purple sweet potato cultivars were analysed quantitatively and qualitatively.•Four complementary methods were applied to evaluate antioxidant activities.•The fingerprint–efficacy relationship was investigated by grey relational analysis.•Seven identified anthocyanins were considered as key constituents of the bioactivity.•A potential platform for cultivar selection and plant breeding was established.