In vitro gastrointestinal digestion and colonic fermentation of phenolic compounds in UV-C irradiated pineapple (Ananas comosus) snack-bars

Pineapple (Ananas comosus) is a widely consumed tropical fruit. UV-C irradiation reduces the microbial load of fruits and contributes to the increase their content of phenolic compounds (PCs). Snack-bars were prepared batch using UV-C irradiated pineapple slices (irradiated pineapple bar, IPB) or with non-irradiated pineapple slices (non-irradiated pineapple bar, NIPB). Both snacks-bar samples were submitted to simulated gastrointestinal digestion and in vitro colonic fermentation, to evaluate the in vitro bioaccesiblility of PCs present in these fruit-based products. The bioaccesibility of PCs in both samples at the end of the digestion process was 45%. PCs in the intestinal phase increased about 52.7% (NIPB) and 62.8% (IPB) compared to the gastric phase, a change that indicates how many of the PCs cross the intestinal barrier. Twenty-six different compounds, including flavonoids, hydroxycinnamic and phenolic acids were identified in the digested samples. The non-digestible fraction submitted to colonic fermentation, was rich in flavonoids, mostly gallocatechin. This compound was degraded and biotransformed by the gut microbiota producing different compounds, including 3-hydroxybenzoic and 4-hydroxyphenylacetic acids. The study of the bioconversion of PCs present in different food matrices stress the relevance of the metabolites produced during the colonic fermentation.