Some basic psychophysics of calcium salt solutions

Detection thresholds and the taste qualities of suprathreshold concentrations of calcium salt solutions were assessed. Average taste detection thresholds for calcium chloride (CaCl2), lactate (CaLa), hydroxide, phosphate and gluconate ranged between 8 and 50 mM, with no reliable differences among the various salts. Between-subject variability ranged over four orders of magnitude and reliability coefficients for repeated detection threshold tests of CaCl2 averaged r = 0.52. In an odor detection test, subjects could reliably discriminate 100 but not 1 mM CaCl2 and CaLa from water. The taste of suprathreshold concentrations (1-100 mM) of CaCl2 and CaLa was considered unpleasant. At 1 mM, CaCl2 solution was rated as 35% bitter, 32% sour, 29% sweet and 4% salty. At higher concentrations the sweet component diminished and the salty component increased, so that 100 mM CaCl2 was rated as 44% bitter, 20% sour, 1% sweet and 35% salty. CaLa solutions were considered to be significantly less bitter and marginally more sour than equimolar CaCl2 solutions. Thus, the taste of calcium varied with both the form and concentration of salt tested, but included both sour and bitter components. Saltiness was identified only in high (> or = 32 mM) concentrations of CaCl2, and thus was not necessarily a component of calcium taste.