Multiscale Elucidation of Taste Interactions in Osmanthus Green Tea: Bitter Masking via EGCG and Phenylethanoid Glycoside Interplay

This study revealed the molecular mechanism by which Osmanthus fragrans masks the bitterness of summer-autumn green tea infusion. Taste dilution analysis identified catechins such as EGCG in green tea as the primary bitter compounds. Phenylethanoid glycosides (PhGs), such as verbascoside and salidroside in Osmanthus fragrans exhibited significant bitter-masking effects. Molecular docking identified TAS2R31 as the primary bitter receptor for EGCG, with verbascoside or salidroside competitively disrupting the EGCG-TAS2R31 binding. Molecular dynamics simulations showed that PhGs altered the TAS2R31 conformation, reducing its α-helix content, increasing structural flexibility, and decreasing hydrogen bonding with EGCG. This conformational change correlated with a decrease in the binding affinity of TAS2R31 for EGCG. Spectroscopic analysis further demonstrated that PhGs efficiently quenched the intrinsic fluorescence of TAS2R31. Thus, the Osmanthus-derived PhGs were a key substance that reduces the bitterness of OSGT, which could affect the binding between EGCG and bitterness receptors by altering the conformation of bitterness receptors.