Analysis of single malt Scotch whisky using Raman spectroscopy

Counterfeit and adulterate alcoholic beverages represent an economic problem for the producer but also a potential health issue for the consumer. This is particularly true for single malt Scotch whisky after decades of maturation resulting in high monetary as well as non-material value. A nonintrusive approach for analyzing the content of a whisky bottle without opening the lid is used in the present work. Raman spectra are acquired through the glass wall of the bottle using a 785 nm laser as excitation source. This wavelength is beneficial as moderate fluorescence signals contribute to the spectra and carry additional information. The systematic analysis of the data yields information about the production and maturation procedure. Principal component analysis (PCA) mainly allows determining the cask type, in which the whisky was aged. Partial least-squares regression facilitated the determination of the age, the alcohol content, the filtering process, and whether or not a whisky contains artificial colorants. Hence, it can be concluded that Raman spectroscopy is ideally suited for analyzing whisky and for its authentication.