Protein structure modification and allergenic properties of whey proteins upon interaction with tea and coffee phenolic compounds

Abstract

Structural changes and allergenicity of whey proteins (WPI) upon complexation with caffeic acid (CA) and (-)-epigallocatechin gallate (EGCG) at acidic and neutral pH conditions were investigated. WPI-phenolic compounds interactions were evidenced by fluorescence quenching, accompanied by red-shift (32 nm in WPI-CA and 3 nm in WPI-EGCG). Negative exothermic enthalpy obtained by isothermal titration calorimetry analysis (–5966.4 ± 733.7 kJ/mol for WPI-CA and −14378.3 ± 2363.8 kJ/mol for WPI-EGCG) and reduction of surface hydrophobicity suggest that those interactions are of non-covalent nature. Additionally, changes in secondary structure pattern and increase in thermal stability were demonstrated by circular dichroism and were higher in neutral than in acidic conditions. WPI-EGCG complexes obtained in both pH conditions showed a reduced IgE-binding capacity to β-lg and BSA, two important allergens in milk. In conclusion, we suggest that complexation with EGCG could be a promising strategy to reduce the allergenicity of whey proteins.