PHYSICOCHEMICAL AND PSYCHOPHYSICAL CHARACTERISTICS OF BINARY-MIXTURESOF BULK AND INTENSE SWEETENERS

Correlating psychophysical characteristics with physicochemical proper ties of sweeteners is of relevance to the understanding of the origin of sweetener synergy, an essential parameter for the food manufacturer . Psychophysical evaluation was carried out on bulk sweeteners (sucros e and maltitol) and intense sweeteners (aspartame, sodium cyclamate, a cesulfam-K, alitame) in mixtures. The concentrations of mixtures were calculated to be equisweet to 10% sucrose and sweetness intensity was evaluated by reference to sucrose solutions using a ''sip and spit'' m ethod. While a positive synergistic phenomenon is observed for sugar/s odium cyclamate and maltitol/acesulfamK mixtures, a significant suppre ssion effect is obtained when aspartame is added to sugars. Additivity is observed for sucrose/alitame and sucrose/acesulfamK mixtures. The origin of these differences lies in the influence of the two molecules on water structure and in the nature of their hydration. From physico chemical properties (intrinsic viscosity, Huggins coefficient, apparen t specific volume, hydration number, surface tension and contact angle ), alitame and aspartame seem characterised by hydrophobic hydration; sodium cyclamate, as well as the bulk sweeteners, appear more compatib le with water structure and possess hydrophilic hydration. ACK is diff erentiated from other sweeteners by a negative hydration. Synergy occu rs when components with identical types of hydration are mixed. This p henomenon is accompanied by an increase in the mobility of water molec ules in the proximity of bulk sweeteners (maltitol and sucrose) and a reduction of volume of the hydrated solute molecule. Inversely, suppre ssion and additivity occur when constituents of the mixture possess di fferent natures of hydration, as in sucrose/ aspartame mixtures, and w hen physicochemical properties show a reduction of the mobility of wat er around the sweeteners. For suppression effects, an increase in volu me of the hydration sphere is also observed. Interpretation of the swe etness of mixtures of sugars and artificial sweeteners, in terms of th eir compatibility with water structure, is of relevance at an economic level in food formulations. (C) 1998 Elsevier Science Ltd. All rights reserved.