Optimization of anthocyanidins conversion using chokeberry pomace rich in polymeric proanthocyanidins and cellular antioxidant activity analysis

Chokeberry pomace contains abundant polymeric proanthocyanidins with low antioxidant activity and bio-accessibility. In this study, polymeric proanthocyanidins from chokeberry pomace were converted into anthocyanidins with higher antioxidant activity. Optimal conversion conditions were determined by full factorial design. The composition of anthocyanidin was analyzed by TOF-MS and UPLC. In addition, the antioxidant activity of the conversion products was evaluated by PSC and CAA assays. The results showed that the yield of anthocyanidins was 11.59 mg/g when the pomace was treated with 95% ethanol concentration, 50:1 liquid-solid ratio, 4% hydrochloric acid and 0.2 mg/mL ammonium ferric citrate concentration at 80 degrees C for 30 min. The newly generated anthocyanidins were identified as cyanidin, which accounting for 51.3% of the total anthocyanidins. The antioxidant activity values of PSC and CAA increased 2.81 and 4.77 folds respectively. The proposed method provides a new strategy for preparation of antioxidants from naturally abundant polymeric ones.