Some taste molecules and their solution properties

The solution properties of a variety of different sapid substances from all four basic taste modalities, namely, sweet (n = 24), salty (n = 7), sour ( n = 11) and bitter (n = 2), have been investigated. Some multisapophoric mo lecules, i.e. molecules exhibiting more than one taste, have also been incl uded in the study in an attempt to define their properties in relation to t he tastes they exhibit; eight sweet-bitter and three sally-bitter molecules were used. The density and sound velocity of their solutions in water have been measured and their apparent volumes, apparent compressibilities and c ompressibility hydration numbers calculated and compared. Apparent molar vo lumes (phi v) and apparent specific volumes (ASV) reflect the state of hydr ation of the molecules, and thus their extent of interaction with water str ucture. The range of ASVs reported are 0.13-0.49 cm(3)/g for salty molecule s, 0.55-0.68 cm(3)/g for sweet molecules, 0.53-0.88 cm(3)/g for sweet-bitte r molecules and a much wider range (0.16-0.85 cm(3)/g) for sour molecules. Isentropic apparent specific compressibilities range from -2.33 x 10(-5) to -8.06 x 10(-5) cm(3)/g.bar for salty molecules, -3.38 x 10(-7) to -2.34 x 10(-5) cm(3)/g.bar for sweet molecules, +6.35 x 10(-6) to -2.22 x 10(-5) cm (3)/g.bar for sweet-bitter molecules and +6.131 x 10(-6) to -2.99 x 10(-5) cm(3)/g.bar for sour molecules. Compressibility hydration numbers are also determinable from the measurements of isentropic compressibilities and thes e reflect the number of water molecules that are disturbed by the presence of the solutes in solution. This study also shows that it is possible to gr oup isentropic apparent molar compressibility values by the taste quality e xhibited by the molecules in the same order as for ASV.