Simulated gastrointestinal digestion and in vitro colonic fermentation of date (Phoenix dactylifera L.) seed polyphenols

Summary Date seeds are a by‐product of date fruit industry and a rich source of polyphenols. In this study , in vitro bioaccessibility and colonic fermentation of major polyphenols from date seed powder ( DSP ) and DSP ‐fortified yoghurt ( DSPY ) were investigated using HPLC . Catechin, epicatechin and procyanidin A2, B1 and B2 were stable during simulated gastric and sequential intestinal digestion. Bioaccessibility was significantly ( P < 0.05) higher for all compounds from DSPY compared with DSP . After in vitro colonic fermentation of insoluble digestion materials, most of the target compounds were metabolised by faecal bacteria to ferulic acid, 3‐hydroxyphenylacetic acid, 3‐phenylpropionic acid and 3‐(4‐hydroxyphenyl) propionic acid. DSPY contained significantly ( P < 0.05) higher level of free polyphenols as indicated by higher bioaccessibility; however, the stability of the polyphenols and their fermentation products from DSPY were similar to that of DSP alone. These data would be useful in product developments incorporating DSP as a source of polyphenols in food products.