Evaluation of the Bitter-Masking Potential of Food Proteins for EGCG by a Cell-Based Human Bitter Taste Receptor Assay and Binding Studies

Epigallocatechin gallate (EGCG) has been ascribed to several health benefits, but its bitter taste influences the liking of products with high concentrations of this compound. β-Casein, in particular, and several gelatins are known as strong binders of EGCG, contrary to β-lactoglobulin. The current study aimed at relating the EGCG-binding characteristics of those proteins and their food-grade equivalents to their effects on reducing bitter receptor activation by EGCG in vitro and their bitter-masking potential in vivo. Also in the bitter receptor assay, β-casein showed the strongest effect, with a maximum reduction of hTAS2R39 activation of about 93%. A similar potency was observed for Na-caseinate. β-Lactoglobulin had little effect on bitter receptor activation, as expected based on its low binding affinity for EGCG. The bitter-masking potential of Na-caseinate was confirmed in vivo using a trained sensory panel. β-Lactoglobulin also slightly reduced EGCG bitter perception, which could not be directly related to its binding capacity. The bitter receptor assay appeared to be a valid tool to evaluate in vitro the efficacy of food proteins as complexing agents for masking bitterness.