Bitterness of sweeteners as a function of concentration.

Sixteen trained tasters provided sweetness and bitterness intensity ratings for 19 compounds including: acesulfame-K, alitame, aspartame, fructose, glucose, glycine, lactitol, maltitol, monoammonium glycyrrhizinate, neohesperidin dihydrochalcone, neosugar (fructo-oligosaccharide), palatinit (isomalt), rebaudioside-A, sodium cyclamate, sodium saccharin, stevioside, sucralose, sucrose, and thaumatin. With increasing concentration, high-potency sweeteners including acesulfame-K, neohesperidin dihydrochalcone, sodium saccharin, rebaudioside-A, and stevioside tended to become more bitter. Low-potency sweeteners including fructose, sucrose, and lactitol tended to become less bitter with increasing concentration.

Adaptation of sweeteners in water and in tannic acid solutions.

Repeated exposure to a tastant often leads to a decrease in magnitude of the perceived intensity; this phenomenon is termed adaptation. The purpose of this study was to determine the degree of adaptation of the sweet response for a variety of sweeteners in water and in the presence of two levels of tannic acid. Sweetness intensity ratings were given by a trained panel for 14 sweeteners: three sugars (fructose, glucose, sucrose), two polyhydric alcohols (mannitol, sorbitol), two terpenoid glycosides (rebaudioside-A, stevioside), two dipeptide derivatives (alitame, aspartame), one sulfamate (sodium cyclamate), one protein (thaumatin), two N-sulfonyl amides (acesulfame-K, sodium saccharin), and one dihydrochalcone (neohesperidin dihydrochalcone). Panelists were given four isointense concentrations of each sweetener by itself and in the presence of two concentrations of tannic acid. Each sweetener concentration was tasted and rated four consecutive times with a 30 s interval between each taste and a 2 min interval between each concentration. Within a taste session, a series of concentrations of a given sweetener was presented in ascending order of magnitude. Adaptation was calculated as the decrease in intensity from the first to the fourth sample. The greatest adaptation in water solutions was found for acesulfame-K, Na saccharin, rebaudioside-A, and stevioside. This was followed by the dipeptide sweeteners, alitame and aspartame. The least adaptation occurred with the sugars, polyhydric alcohols, and neohesperidin dihydrochalcone. Adaptation was greater in tannic acid solutions than in water for six sweeteners. Adaptation of sweet taste may result from the desensitization of sweetener receptors analogous to the homologous desensitization found in the beta adrenergic system.

Taste perception of sodium chloride in relation to dietary intake of salt.

Normotensive young adults, categorized as having high, medium, or low dietary intakes of salt based on a food habits questionnaire, participated in a series of discrimination, perceived intensity, and preference tests of solutions of NaCl and of salted tomato juice. In ad libitum preference tests, subjects with a low salt intake added less NaCl to salt-free tomato juice, and had higher salivary sodium levels. However, large individual variability precluded discernment of a clear-cut relation among these measures. No significant correlations were obtained between salt intake and detection thresholds of 57 subjects for NaCl in water or in juice. In water solutions, salt recognition was greater for the high intake group than for the other groups, with a reverse trend for tomato juice. The experiments demonstrated that 1) discrimination, sensitivity, perceived intensity, preference, and hedonic responses to salt were independent behavioral measures; 2) few sensory measures were related to estimated salt intake; 3) patterns of response to saltiness could not be extrapolated from water solutions to the more complex juice, 4) NaCl elicited a variety of qualitative responses, depending on concentration and medium of dispersion, and 5) a more accurate test instrument is needed for estimating dietary intake of salt.