SOLUTION PROPERTIES AND THE MASKING OF UNPLEASANT TASTES OF NICOTINE – SWEETENER – WATER MIXTURES

Solutions properties of sapide molecules provide fundamental information on type (hydrophobic or hydrophilic) and degree of hydration. Physico-Chemical properties like intrinsic viscosity, Apparent Specific Volume (ASV) and related parameters for bitter molecule (nicotine) and bitterness inhibitors (carbohydrate sweeteners, artificial sweeteners) and their mixtures were determined to study the role of water structure in the mechanism of unpleasant taste inhibition. The hydrophobicity of bitter molecule (nicotine) is manifested by ASV value of 0.920 cm³g^-1 obtained in artificial buffered saliva (pH »8.2). Under these conditions nicotine (3-(1-methyl-2-pyrrolidinyl)pyridine is in neutral form, the most potentially hydrophobic. Experimental results indicate that viscometric constant (intrinsic viscosity [ƞ], Huggins constant k’, B coefficient) could discriminate between different sapid molecules tested at our laboratory. The ASV value of carbohydrate sweeteners falls within the sweet region. The bitterness of nicotine is manifested by ASV as high as 0.920 cm³g^-1, which falls in the bitter region. Solution properties also determined for sweet-bitter mixtures validate an improvement in the fitting of solute molecules with solvent structure through the decrease of ASV which falls in the range of ASVs of sweet molecules.  The results of viscometric constants and hydration number of sweet-bitter mixtures illustrate an obvious effect of sweet molecules on the hydration property of nicotine.  The effect of sweetener on the solution property of bitter molecule (nicotine) is attributed to a modification of hydration.  This experimental result validates the assumption in designating sweetener as bitterness inhibitor. The mechanism of inhibition of bitterness by sweet molecules may be credited to the arrangement of water molecules hydration which is more mobile.