Taste quality profiles for fifteen organic and inorganic salts

Biophysical studies of isolated taste receptor cells show that one transduction mechanism for Na+ salts involves the inward movement of Na+ through an apical ion channel, which is sensitive to the diuretic amiloride. An additional paracellular pathway also appears to be involved in NaCl transduction, but not in the transduction of organic Na+ salts. Little is known, however, about how these receptor mechanisms relate to taste perception. Recent human psychophysical studies suggest that the amiloride-sensitive transduction pathway is coupled to the sour side taste of these salts rather than to their saltiness. In the present study, we employed direct magnitude estimation of taste intensity and quality of fifteen organic and inorganic Na+, Li-, K+, and Ca+2 salts. Many salts had multiple taste qualities, such as the salty and bitter tastes of NH4Cl and KCl; the Ca+2 salts were predominantly bitter. Taste quality often changed with stimulus concentration. Multivariate analyses of their taste profiles resulted in a grouping of these 18 stimuli within a taste space bounded by NaCl, sucrose, citric acid, and QHCl, with the organic salts positioned between NaCl and citric acid. The organic Na+ salts and the Li+ salts were considerably less salty and proportionately more sour than NaCl. These results, combined with previous work showing that amiloride suppresses the sourness of NaCl and Na-gluconate, predict that the organic Na+ salts and the Li+ salts would be more greatly suppressed by amiloride treatment than would NaCl.