Conversion of condensed tannin from chokeberry to cyanidin: Evaluation of antioxidant activity and gut microbiota regulation

Chokeberries contain a large amount condensed tannin. In this study, hot acid-alcohol treatment was used to convert the condensed tannin into cyanidin, so as to give them higher antioxidant activity and improve the function of gut microbiota. The total cyanidins yield was taken as the index. The effects of various factors on the total cyanidins yield were analysed by the single factor experiment and factor design experiment. In addition, the response surface methodology was used to obtain the optimal conversion conditions. The cyanidin composition and cellular antioxidant activity of products was detected. Through simulated digestion and fermentation in vitro, improvement of gut microbiota was evaluated. The results show that the product obtained by the optimal conversion treatment conditions, which could increase total cyanidins yield 1.50 folds to 28.88 mg/g. The total antioxidant activity and cellular antioxidant activity increased by 1.85 folds and 1.56 folds, reaching 3905.48 (μmol Vit C equiv./100 g FW) and 2329.31 (μmol QE/100 g FW), respectively. Conversion treatment could change the some negative effect of chokeberry on gut microbiota diversity into the positive effect.