In vitro bioaccessibility of polyphenolic compounds: The effect of dissolved oxygen and bile

Polyphenols are acknowledged as health-promoting compounds, yet also known for their low bioavailability. Thus, the evaluation of their bioaccessibility, as a principle parameter for bioavailability, is important. In-vitro digestion is a common method for assessing polyphenol bioaccessibility, however, the method conditions don't address the potential influence of two important factors: dissolved oxygen (DO) and bile. This study explored the bioaccessibility of seven polyphenols as influenced by those factors, based on standard protocol as control. The results revealed a structure-dependant bioaccessibility, with up-to 54 % higher bioaccessibility in 0 % DO compared to control (100 % DO). However, bile has a larger influence, where intestinal bioaccessible pelargonidin-3-O-glucoside was higher by 123.91 ± 0.06 % without bile compared to the standard protocol (p < 0.05). These findings may partially refute the assumption of massive anthocyanin degradation in the intestinal conditions as the reason for poor anthocyanin bioavailability, and be used to develop a more specific method for in-vitro polyphenols digestion studies.