Volatiles Characterization during Whiskey Production using Headspace - Solid Phase Microextraction - Gas Chromatography - Mass Spectrometry
Abstract
Whiskey is the second most consumed distilled alcoholic beverage type, by brand, on the planet behind Chinese Baijiu. A prominent component in many varieties of whiskey, maize, contributes a wide profile of compounds that undergo modification in the production pathway, ultimately influencing the final flavor profile. In this study, headspace/solid phase microextraction-gas chromatography/mass spectrometry (HS/SPME-GC/MS) was used to characterize the volatile profile of 5 different maize varieties, mashes produced from each, and 4 post-fermentation mixtures. Headspace sampling was performed using a high capacity SPME Arrow device, in an effort maximize the species detected. Compound identification was supplied by matches within the NIST17 library of compound spectra. The statistical treatments of principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used on a 143-peak list derived from the dried maize samplings as an effort to substantiate visual, qualitative differences between the 5 varieties’ volatile profiles. Mash and beer samples prepared from 4 of the maize cultivars were compared with both liquid injections and HS/SPME analyses, with greater differences apparent amongst the beers, in either introduction method. The species observed across the analyses are consistent with glycolytic and fermentation products, suggesting that the HS/SPME sampling parameters on the dried maize served as a pseudo- “dry mashing” procedure.