Hydrogen bonding of water–ethanol in alcoholic beverages

An alcoholic beverage is a type of water–ethanol solution with flavor and taste. The properties of the hydrogen bonding of water–ethanol in alcoholic beverages have not been clarified sufficiently. We investigated factors that could affect the hydrogen-bonding structure of water–ethanol on the basis of proton nuclear magnetic resonance (1H NMR) chemical shifts of the OH of water–ethanol and Raman OH stretching spectra. Not only acids (H+ and HA: undissociated acids) but also bases (OH− and A−: conjugate-base anions from weak acids) strengthened the hydrogen-bonding structure of water–ethanol. It was also demonstrated that the hydrogen bonding is strengthened by chemical components in alcoholic beverages (whiskey, Japanese sake, shochu). It can be suggested that hydrogen-bonding donors as well as acceptors in alcohol beverages, which exist as the initial components or are gained later on, should cause the tight association between water and ethanol molecules.