WASHINGTONScientists have identified a chemical basis for peoples preference for certain brands of vodka. The findings, published in the Journal of Agricultural and Food Chemistry, reveal that vodka differs from simple water-ethanol solutions in ways that could alter vodkas perceived taste.

Researchers noted vodka has a long-standing reputation as a colorless, tasteless solution of 40 percent pure ethyl alcohol, or ethanol, and 60 percent pure water. All such beverages should have the same faint or undetectable taste; however, sales of premium vodka brands have surged in recent years.

Researchers used high-tech instruments to analyze the composition of five popular vodka brands. They found that each vodka brand differed in its concentration of ethanol hydrates. Vodka drinkers could express preference for a particular structure. Drinkers actually may perceive this internal structure or structurability of vodka, rather than taste in a traditional sense.

We began this discussion with the statement that vodka is a colorless, tasteless water-ethanol solution. So how do vodka drinkers develop brand preference? Our answer is structure. Beverages with low structurability are likely to be perceived as watery, because the fraction of water clusters is higher than in brands with high structurability. Beverages with high structurability, on the other hand, harbor transient cage-like entities where the ethanol molecule is sequestered by surrounding water molecules. At high alcohol content, clusters of alcohol molecules appear . These ethanol clusters undoubtedly stimulate the palate differently from either water or the E5.3H2O cage structure. Even in the absence of taste in the traditional sense, vodka drinkers could express preference for a particular structure.