Abstract:In this study，solid acid catalysts were used to degrade the polymeric proanthocyanidins from black tartary buckwheat shells.Through single-factor test and orthogonal test，the degradation conditions were optimized，and the structures of the degradation products were characterized to investigate their antioxidant activities.The results showed that the optimum solid acid catalyst screened out was Amberlyst-35（A-35），and the optimal degradation conditions were listed below：10% catalyst addition（w:w），catalysis time of 40 min，and catalysis temperature of 65 ℃.Under these conditions，the average polymerization degree of the polymeric proanthocyanidins decreased from 6.89 to 2.37.The degradation products were characterized by Fourier transform infrared spectroscopy（FTIR）and confirmed to have structural characteristics of proanthocyanidins，indicating a good degradation effect.In addition，the scavenging abilities of DPPH free radicals and ABTS＋free radicals of the degradation products increased by 1.92 times and 4.78 times，respectively，and there was no significant difference in the chelating capacity of Fe2+.In conclusion，polymeric proanthocyanidins from black tartary buckwheat shells were degraded to obtain oligomeric proanthocyanidins with strong antioxidant activity.