THE EFFECT OF SWEETENERS ON BITTER TASTE IN YOUNG AND ELDERLY SUBJECTS

The purpose of this study was to quantify the degree of reduction in p erceived bitterness by sweeteners at both threshold and suprathreshold concentrations of bitter compounds. Detection and recognition thresho lds were determined for six bitter compounds (caffeine, denatonium ben zoate, magnesium chloride, quinine hydrochloride, sucrose octaacetate, and urea) in the absence and presence of several suprathreshold conce ntrations of five sweeteners. The sweeteners were: sucrose, aspartame, sodium saccharin, mannitol, and sorbitol. Polycose was also tested al ong with the sweeteners. The degree to which bitter thresholds were af fected by the addition of sweeteners was dependent on the chemical cla ssification of the sweeteners and their concentrations. In general, th e natural sweeteners, sucrose, mannitol, and sorbitol, were more effec tive than the noncaloric sweeteners, aspartame and sodium saccharin, i n elevating the detection and recognition thresholds of the bitter com pounds. A sweetness intensity approximating that of 6% sucrose (0.175 M sucrose) or greater was required to elevate thresholds. For elderly subjects, sweeteners did not significantly elevate thresholds for dena tonium benzoate and sucrose octaacetate. The degree to which sorbitol and sucrose can decrease the perceived bitterness intensity of suprath reshold concentrations of the six bitter compounds was also determined . The concentrations of sweeteners and bitter compounds were selected to be of moderate to high subjective intensity. The levels of sweetene rs used in the mixtures were: sucrose (none, 0.946 M, and 2.13 M) and sorbitol (none, 2.1 M, and 3.68 M). Both sweeteners significantly redu ced the bitterness ratings of almost every concentration of the six bi tter compounds. The greatest reductions in bitterness were 87.0% for 0 .199 mu M denatonium benzoate mixed with 2.13 M sucrose and 84.7% for 1.8 M urea mixed with 3.68 M sorbitol.