Functional assays for identifying compounds that activate or modulate the activation of the T1R1/T1R3 (umami) taste receptor are provided. These assays detect the effect of one or more compounds on the activation of T1R1/T1R3 (umami) taste receptor or on the activation of T1R1/T1R3 umami taste receptor by another compound e.g., monosodium glutamate, lactisole, or another unami taste modulator. These assays preferably are cell-based functional assays and typically use cells, e.g., HEK-293 cells that express a G protein such as G.sub..alpha.15, G.sub..alpha.16 or gustducin. Compounds identified in the disclosed functional assays are potentially useful as flavor additives in compositions for human or animal consumption.