Perception of taste intensity in solutions of random-coil polysaccharides above and below c

Sensory paired comparison tests were used to study differences in taste intensity in solutions of hydroxypropylmethyl cellulose (HPMC) at concentrations above (1.0% w/w) and below (0.2% w/w) c^*, the coil-overlap concentration (the point at which viscosity changes abruptly with increasing thickener). The sweetness intensities of aspartame (250 ppm), sucrose (5% w/w), fructose (4.5% w/w) and neohesperidin dihydrochalcone (39 ppm) and the saltiness of sodium chloride (0.35%) were all found to be significantly reduced in the more viscous HPMC solution. There was no significant effect of HPMC concentration on the acidity of citric acid (600 ppm) or the bitterness of quinine hydrochloride (26 ppm). The sweetness intensities of sucrose and aspartame were likewise investigated in two further hydrocolloid solutions, guar gum and λ-carrageenan. Experiments were designed so that the ratios of the thickener concentrations (above and below c^*) to their measured c^* values remained constant. The sweetness of sucrose was found to be significantly reduced in the more viscous guar gum solution (P<0.05) and that of aspartame was reduced in the λ-carrageenan above c^* (P<0.001). A multiple paired comparison design was used to show that the perceived sweetness of 6.5% sucrose in 1.0% HPMC did not differ significantly from that of 5% sucrose in 0.2% HPMC. The magnitude of effect with aspartame was broadly analogous.