Binding affinity between dietary polyphenols and β-lactoglobulin negatively correlates with the protein susceptibility to digestion and total antioxidant activity of complexes formed

► β-Lactoglobulin and polyphenols interact non-covalently in the conditions of the GIT. ► Polyphenol extracts prevented pepsin digestion and β-α non-native transition at acidic pH. ► Coffee and cocoa extracts destabilized protein structure at pH 7.2. ► Total antioxidant capacity was reduced due to protein-polyphenol binding. ► The strength of interactions governs the biological effects examined.