THE FIRST TRACT OF ALIMENTARY CANAL AS AN EXTRACTOR. RELEASE OF PHYTOCHEMICALS FROM SOLID FOOD MATRICES DURING SIMULATED DIGESTION

The release of some phytochemicals (polyphenols, flavonoids, anthocyanins, carotenoids) from peach, plums, prunes, walnuts and tomatoes using an in vitro model simulating oral-gastro-hepato-pancreatic digestion has been investigated. Most of phytochemicals are extracted during the oral phase, and the amount of bioaccessible polyphenols, flavonoids and anthocyanins increased during gastric digestion in all the analyzed fruits. The transition in the hepatopancreatic environment caused a decrease in total polyphenols, whereas flavonoids (except anthocyanins) were not degraded. In most of the tested fruits, the hepatopancreatic digestion did not affect the extraction of polyphenols and flavonoids except in walnuts, for which this phase caused an important release of both of them. Our results suggest that the first tract of alimentary canal may act as an extractor of phytochemicals where the antioxidant compounds are progressively released from food matrix and are made available for the absorption or to exert their biological effects in this area. PRACTICAL APPLICATIONS The results reported in this study on both digestive stability and bioaccessibility (the release of compounds from solid food matrices) of some bioactive components of fruits consumed worldwide could be helpful information for their nutritional and health value. Research concerning the bioaccessibility of polyphenols from solid matrices are important because not all the polyphenols present in the food matrix, but only those released in the first tract of alimentary canal, are really bioaccessible in the gut and, therefore, potentially bioavailable. Moreover, food polyphenols data usually refer to polyphenols analyzed in aqueous and organic extracts of foods. As reported in our work, the amount of bioaccessible food polyphenols may differ quantitatively and qualitatively from polyphenols extracted with chemical methods, so the most bioaccessible polyphenols are not necessarily those present at higher concentration in the food.