Release and metabolism of bound polyphenols from carrot dietary fiber and their potential activity under in vitro digestion and colonic fermentation
Dietary fiber is carrier of abundant polyphenols and the potential benefits of this special substances has attracted growing attention. In this study, in vitro simulated digestion under oral, gastric and intestinal phase and colonic fermentation with human fecal were performed to explore release and metabolism of bound polyphenols from carrot dietary fiber (CDF) and their potential activity. The results indicated that bound polyphenols released by fecal fermented process (30.43%) from CDF were higher than digested process (0.89%). 26 polyphenols and their catabolites were detected, and the microbial pathways of primary polyphenols were proposed. Furthermore, the significant disintegration of sheet-like structure of CDF after in vitro fermentation compared with the digestion treatment. The released polyphenols exhibited antioxidant capacity and α-glucosidase inhibitory activity. The microbe community structure was regulated by fecal fermented CDF through decreasing Firmicutes to Bacteroidetes ratio, improving relative abundance (RA) of beneficial microbiota and suppressed RA of various harmful microbiota. Overall, this study suggested that bound polyphenols might exert potential benefits in gastrointestinal and colonic health of CDF.