Role of water in sweet taste chemoreception*
Gordon G. Birch
School of Food Biosciences, The University of Reading,
P.O. Box 226, Whiteknights, Reading RG6 6AP, UK
Abstract: The mechanistic understanding of sweet taste
chemoreception has been advanced by the microscopic and macroscopic
studies of sweetenerwater interactions. This approach has led
to the concept of water mobility as a key to interpreting sweetness.
The apparent specific volume of a solution is a determinant of its taste
quality, as sweetness is known to be confined to the range 0.510.71
cm3 g-1. Thus, the "ideal" quality of
the sugars is presumed to be due to their occupancy of the center of
this range (i.e., 0.618 cm3 g-1). Most sweeteners
elicit off-tastes and flavors and exhibit different apparent specific
volumes. This leads to the conclusion that taste quality is broadly
determined by the packing characteristics of sweet molecules among water
molecules and the compactness of their hydration shells, expressed as
their apparent specific isentropic compressibilities. The role of water
can, therefore, be applied in modern attempts to optimize sweet taste
quality, and different food salts can be explored as useful taste modifiers.
Salts interact more strongly with water structure than do any other
taste solutes, and it emerges that the ionic charge density is an important
criterion. Such studies show how sweetener formulations are likely to
improve within the next decade.
* A special topic issue on the
science of sweeteners.
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