Untargeted metabolomics reveals changes in phenolic profile following in vitro large intestine fermentation of non-edible parts of Punica granatum L

In this study, the untargeted phytochemical profile of non-edible parts of pomegranate (i.e., flowers, leaves and peels) was depicted by using untargeted metabolomics. Each sample was in vitro digested and then fermented simulating a large intestinal process, then monitoring the changes of phenolic bioaccessibility. The most abundant compounds in pomegranate extracts were polyphenols, terpenoids, sterols, alkaloids and amino acids. The untargeted metabolomic approach revealed a transformation of flavonoids over 24 h of in vitro fermentation. In particular, an increase in the % bioaccessibility for phenolic acids and tyrosols in flowers (probably due to the insoluble dietary fibre content, i.e., 27.1 g 100 g−1) was observed. Accordingly, the highest % bioaccessibility was detected after 24 h of in vitro large intestine fermentation for flower (i.e., 53.8%). Results showed that non-edible parts of pomegranate could be used as ingredients for the development of potential value-added food and industrial products.