Influence of phloretin on acrolein-induced protein modification and physicochemical changes in a dairy protein model

Acrolein (ACR) is an α,β-unsaturated aldehyde with high reactivity towards nucleophiles in proteins. In this study, a typical phenolic compound phloretin (Phl) was employed to counteract protein modification induced by ACR (1 mM) in whey protein isolate (WPI, 10 mg/mL). The addition of Phl (2 mM) significantly reduced ACR-induced surge of protein carbonyls (from 1.65 to 0.65 μmol/mg protein) and loss of protein total sulfhydryl content (from 0.28 to 0.24 μmol/mg protein) whilst contributing to further reductions in protein surface hydrophobicity and intrinsic fluorescence. The incorporation of ACR into WPI was effectively interrupted by Phl as visualized by Western blot. Only 2.87 % of ACR remained in the presence of 2 mM Phl with the generation of Phl-ACR adducts, suggesting Phl could partially alleviate protein modification by scavenging of ACR. These findings could have important implications for employment of natural phenolic nucleophiles against the adverse effects of ACR towards dietary proteins.