High variation of congener alcohols in apple wines.

Congener alcohol (CA) analysis became an important tool in forensic science to prove the kind of alcoholic beverage consumed. The aim of the present study was to determine the influence of yeast strain and apple variety on the formation of congener alcohols in self-produced apple wine. There exist data on CA patterns of industrially produced alcoholic beverages, but these are not available for apple wine. Must from five different commercial as well as from six genuine apple varieties were used for fermentation under similar conditions CA formation was monitored during the fermentation process. Additionally, nine commercial apple wines from commercial producers were analyzed. Analysis was performed by headspaces-GC-MS. All apple wines contained markedly high contents of the CA 3-methylbutan-1-ol (88-251 mg/L). Compared to self-produced apple wines from genuine musts the industrial apple wines (purchased in supermarkets and self-produced from commercial musts) exhibited significant differences in methanol concentrations(8.5-94 mg/L), whereas all other CAs, such as propan-1-ol, butan-1-0l, 2-methylpropan-1-ol(isobutanol), 3-methyl-butan-1-oi, and 2-methylbutan-1-oi, were found to be present in similar concentrations. Methanol was not detectable in apple wine made from genuine musts during fermentation but after a storage period. In some cases, concentrations of some CAs additionally changed during storage. This may be explained by a secondary (unwanted) fermentation after bottling. According to the data obtained in the present study, it is recommended to analyze a sample of the allegedly consumed apple wine in forensic cases, rather than to rely on data obtained from the literature or from some data collections.