Objective To explore the driving force of the oral astringency produced by the interaction of theaflavin（TF） and epigallocatechin-3-gallate（EGCG） to human salivary α-amylase（HSA）. Methods The constants of the rate, equilibrium of reaction（ka, kd , KA, and KD） and Langmuir, Freundlich adsorption isotherm（KL, Kf, and Mm） were determined by surface plasmon resonance（SPR） technique and adsorption kinetics. Results Both of Langmuir and Freundlich models could be used for describing the binding processes of TF and EGCG onto HSA surfaces, and there were no significant differences of the correlation coefficient of determination between these two models（P>0.05）. The constants of adsorption isotherm, the rate and equilibrium constants of the association for TF were higher than those of EGCG（P
