Concentration of Acetic Acid in the Vapor of Aged Sherry Vinegars Stored in Barrele

Abstract

Most vinegars have a strong odor and stimulative taste during the early period of storage after brewing. As they age, their odor and taste become very mild. This interesting phenomenon has been examined in our laboratory. The characteristics of many aged white vinegars have already been investigated using NMR spectra, vapor pressure measurement and DSC thermograms. In this study, the concentration of acetic acid in the vapor of Sherry vinegars stored in barrels for 25 years was investigated in detail. The concentrations of other components in the liquid and vapor of these samples were also analyzed and their effect on the decrease in acetic acid concentration in the samples' vapors was studied. A large decrease in the acetic acid concentration in the vinegar vapor was observed in the presence of ethanol, but ethylacetate, ash and nonvolatile residues extracted from the barrels caused little reduction in acetic acid concentration. The effect of these minor substances on the vapor components of an acetic acid aq. solution with the same level of acidity as the Sherry vinegar samples was investigated in detail. The reduction in acetic acid concentration of the vapor of aged Sherry vinegars was far greater than that produced by the effects of ethanol and other constituents. The mild and non stimulative aroma may be due to a specific liquid state characteristic of aged vinegars, i.e. The formation of a stable molecular cluster which reduces the concentration of monomeric acetic acid molecuies, as indicated the former study on aged White vinegars.