Fig. 4

a–b Extractable and hydrolyzable fractions of PPF and YPF samples. a (TPC, Total phenol content was calculated as the sum of extractable and hydrolysable fraction. The results were expressed as gallic acid equivalents (GAE) per kilogram of dry weight (mg GAE/100 g); b Antioxidant capacity methods: CUPRAC, cupric ion reducing power assay; FRAP, ferric reducing antioxidant power; The results are expressed in terms of micromoles Trolox equivalents per kilogram of dry weight (μmol TE/g). TPC: mg GAE/100 g; CUPRAC: µmol TE/g; FRAP: µmol TE/g; PPF: purple potato flour; YPF: yellow potato flour)