Interaction between β-casein and phlorizin induced by thermal treatment and its effect on the antioxidant activity and bioavailability of phlorizin in vivo

The effect of thermally-induced interactions between β-casein (β-CN) and phlorizin (Phl) on the antioxidant activity and bioavailability of Phl was investigated. Results demonstrated that Phl and β-CN interacted mainly via hydrogen bonds and Van der Waals forces, but that thermal treatment did not stimulate the formation of Phl-β-CN covalent complexes. Thermal treatment increased ABTS values of β-CN-Phl complex by 5.53%∼38.36%, but changed its FRAP little. Hydrogen bonding between Phl and β-CN showed antagonistic effect on their ABTS values. Thermally-induced Phl-β-CN interactions at 121 °C decreased the Pht bioavailability by 58.71%. Thermal treatment at 25–100 °C had non-significant effect on the binding type or strength between Phl and β-CN, whereas treatment at 121 °C decreased the binding strength of Phl-β-CN by 62.86%, which was positively correlated with the decreased bioavailability of Pht. Thermally-induced structure transformation of β-CN was detrimental to Phl bioavailability. This study may provide a theoretical basis for the design of polyphenols-containing dairy products.