Analysis of the aroma compounds of Taiwan draft beer

Abstract

© 2018 Chinese Agricultural Chemical Society. All rights reserved. Beer is one of the most widely consumed beverages in the world. It is derived from the alcoholic fermentation of malt and hops extract, giving rise to its distinct flavour and aroma. The aroma profile of beer is made up of various compounds existing in a delicate balance to give beer its characteristic aroma. As beer aroma is one of its defining traits and therefore of great importance, this study focuses on the establishment of a protocol to quantitate compounds which contribute greatly to the aroma profile. Flavour dilution (FD) factor and odour activity value (OAV) are generally recognized as a reliable indicator of a compound's contribution to aroma. Therefore, 10 aroma compounds which were commonly observed to have high OAV and FD factors in beer were chosen to be the target analytes from which a protocol for their analysis could be established. Diethyl ether was found to be a suitable choice of solvent for the extraction of the target analytes in beer and also minimising analyte loss during solvent removal compared to dichloromethane. The volatilities of the target analytes were also studied and compared, thus allowing for the quantitation protocol to take into account the difference in analyte loss during solvent removal. Using this method, 18 day draft beer from Taiwan Tobacco and Liquor Corporation was analysed using Gas Chromatography - Mass Spectrometry (GC-MS) and the concentrations of the target analytes were found to be within the range of that typical in beers. The change in these aroma compounds were tracked over and beyond the mandated shelf life of 18 day draft beer and it was found that their concentrations decreased over time, especially once past the 18 day mark.