title: Structurability: a collective measure of the structural differences in vodkas.
abstract: Although vodka is a reasonably pure mixture of alcohol and water, beverage drinks typically show differences in appeal among brands. The question immediately arises as to the molecular basis, if any, of vodka taste perception. This study shows that commercial vodkas differ measurably from ethanol-water solutions. Specifically, differences in hydrogen-bonding strength among vodkas are observed by (1)H NMR, FT-IR, and Raman spectroscopy. Component analysis of the FT-IR and Raman data reveals a water-rich hydrate of composition E x (5.3 +/- 0.1)H(2)O prevalent in both vodka and water-ethanol solutions. This composition is close to that of a clathrate-hydrate observed at low temperature, implying a cage-like morphology. A structurability parameter (SP) is defined by the concentration of the E x (5.3 +/- 0.1)H(2)O hydrate compared to pure ethanol-water at the same alcohol content. SP thus measures the deviation of vodka from "clean" ethanol-water solutions. SP quantifies the effect of a variety of trace compounds present in vodka. It is argued that the hydrate structure E x (5.3 +/- 0.1)H(2)O and its content are related to the perception of vodka.
authors.affiliation: Department of Chemical and Materials Engineering, University of Cincinnati, Cincinnati, Ohio 45221-0012, USA.
authors.forename: Naiping
authors.initials: N
authors.lastname: Hu
authors.forename: Dan
authors.initials: D
authors.lastname: Wu
authors.forename: Kelly
authors.initials: K
authors.lastname: Cross
authors.forename: Sergey
authors.initials: S
authors.lastname: Burikov
authors.forename: Tatiana
authors.initials: T
authors.lastname: Dolenko
authors.forename: Svetlana
authors.initials: S
authors.lastname: Patsaeva
authors.forename: Dale W
authors.initials: DW
authors.lastname: Schaefer
mesh_terms: D000431:Ethanol / Q000737:chemistry; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D013059:Spectrum Analysis, Raman; D014867:Water / Q000737:chemistry; D014920:Wine / Q000032:analysis*
chemical_list: D014867:Water; D000431:Ethanol