Assessing bioaccessibility and bioavailability in vitro of phenolic compounds from freeze-dried apple pomace by LC-Q-TOF-MS

Apple pomace is one of the most abundant by-product in fruit processing industry. In this work, fresh and freeze-dried apple pomace variety ‘Red Delicious’ apples “I.G.P. Poma de Girona” was used to evaluate the potential amount of phenolic compounds available from the food matrix by in vitro bioaccessibility test. After the simulated digestion of freeze-dried apple pomace, an in vitro bioavailability test by using differentiated Caco-2 cells simulating the intestinal barried were assayed for 1 h, 2 h, 3 h and, 4 h. LC-Q-TOF-MS has permitted to perform a monitoring of phloridzin, chlorogenic and gallic acids in apple pomace in apical and basal compartments. Results obtained with LC-Q-TOF-MS demonstrated that chlorogenic acid had greater percentage of bioaccesibility (44%), than phloridzin (17%) and gallic acid (7%), with similar values for fresh and freeze-dried samples. Moreover, only chlorogenic acid reported higher bioavailability in basal compartments after 3 h and 4 h, in particular about 56% of chlorogenic acid passed the transepithelial barrier. This is the first work about the evaluation of bioavailability of polyphenols from digested freeze-dried apple pomace extract. Therefore, this interesting by-product rich in polyphenol, with a great bioavailability, should be a promising ingredient to develop new functional foods.