Use of metabolomics and fluorescence recovery after photobleaching to study the bioavailability and intestinal mucus diffusion of polyphenols from cauliflower waste

• Bioavailability of polyphenols was determined using multivariate techniques.
• Intestinal diffusion of polyphenols was determined using FRAP.
• Polyphenol diffusion in ex vivo intestinal mucus was described for the first time.
• Kaempferol glycosides were found to penetrate through Caco-2 cells intact.

The analysis of the bioaccessibility and bioavailability of polyphenols from cauliflower waste was achieved using targeted metabolomics and chemometric approaches. Changes in phenolic profile throughout the in vitro digestion and Caco-2 transport were investigated using LC-MS combined with principal components analysis and orthogonal partial least squares–discriminant analysis, and diffusion of polyphenols through intestinal mucus was monitored using fluorescence recovery after photobleaching (FRAPb). Results showed that recovery of polyphenols in the gastric phase was approximately 76–106% whilst losses of up to 70% were observed after the intestinal phase. Kaempferol-3-O-diglucoside and kaempferol-3-O-diglucoside-7-O-glucoside were found to permeate intact through the Caco-2 cells in very small amounts (0.3% recovery). Polyphenols also diffused rapidly through intestinal mucus without altering their biophysical properties. We conclude that targeted metabolomics and FRAPb are rapid and convenient tools to study the recovery of polyphenols during in vitro digestion, mucosal diffusion and Caco-2 transport.