Current challenges in polyphenol analytical chemistry

•The fate of o-dihydroxybenzenes in foods is only poorly understood.•Colonic and phase-II metabolites have been the focus of bioavailability studies.•Appropriate sample preparation and accurate MS are prerequisites for the analysis.

Polyphenols have been associated with various beneficial activities such as antioxidative, antimicrobial or antiproliferative effects. Therefore, they are used as functional ingredients in foods or dietary supplements. Because of the pronounced complexity of this class of compounds, multidisciplinary approaches are needed to characterize these bioactive compounds from food to blood. Understanding polyphenol interactions with other food ingredients like proteins or dietary fiber is of great importance because complex reactions during food processing can take place. Furthermore, these interactions may affect bioaccessibility, as covalently bound polyphenols differ in their food matrix release during absorption in humans. Current research is questioning the accuracy of polyphenol analysis in physiological samples and more studies in this field are required.