THE CHEMICAL BASIS OF SWEETNESS PERCEPTION IN BEVERAGES

For the chemist, sweet taste perception must begin with the simple principles of chemoreception. Molecules endowed with an appropriate 'Glucophore' are able to interact with, and elicit a response in, a putative receptor. The challenge is thus to explore the structures of sweet molecules, their modification in the environments in which they are presented and their access to, and activation of receptors. A recent approach to structure-activity relationships in sweeteners has centred on the role of water. This has led to a clearer picture of the real hydrated state of sweet molecules and differences between them based on their solution properties. The role of water is of particular relevance in beverages and offers the tantalising prospect of sensory control of formulations based on objective solution measurements. Parameters such as H-1 NMR pulse relaxation times, intrinsic viscosities and apparent specific volumes can be compared to evaluate the solution behaviour of sweet molecules. Apparent specific volumes offer direct experimental verification of computed volumes and, more importantly, are measures of the effective volumes of sweet solutes in the vicinity of receptor sites. They have already been shown to be broad determinants of taste quality. Sweet molecules belong to vastly different chemical classes and they elicit different qualities, intensities and persistences of response. Future progress in the optimisation of sweet taste perception may lie in enhancement or inhibition of the response and control of solution interactions