Role of smoke withering process in the bitterness amelioration effect on smoked Lapsang Souchong tea

Smoked Lapsang Souchong tea (SLST) is renowned for its unique smoky aroma and relatively low bitterness, attributed to the pinewood smoke withering (SW) process. This study investigated the role of SW in reducing SLST bitterness through an integrated approach. Electronic tongue analysis, sensory evaluation, and cell-based calcium imaging assay confirmed that SW significantly reduced tea bitterness. Untargeted metabolomics revealed SW substantially decreased key bitter phenolics, including 10 monomeric catechins, 14 glycosylated flavonols, and 6 galloylated phenolic acids. Concurrently, key pinewood smoke odorants, guaiacol and α-terpineol, directly inhibited TAS2R14 activation by pre-smoke withered tea extract, reducing intracellular calcium signaling by 37% and 21%, respectively. Quantum chemistry calculations further demonstrated that these odorants readily interact with bitter compounds primarily through intermolecular hydrogen bonding and van der Waals forces, suggesting a potential mechanism for inhibiting bitter taste signaling. This study provides novel insights into how smoke withering refines tea flavor by attenuating bitterness.