An assessment of spent coffee grounds as a replacement for peat in the production of whisky: chemical and sensory analysis of new make spirits†

Abstract

The chemical composition of whisky spirits produced using malt smoked with spent coffee grounds (SCG) or traditionally peated were established using high resolution ¹H NMR spectroscopy and Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry. Extracts of malts used for the process were also analysed using Gas Chromatography-Mass Spectrometry. Analytical findings were augmented by sensory analysis to establish whether differences and similarities observed between samples translate to the human sensory experience. Our studies revealed notable matches between new make spirits produced using different sources of smoke, including the presence of several phenolic species related to smoky aroma, such as phenol, and ortho- and para-cresol. The greatest differences were observed in pyridine and furan species concentrations, which were notably higher in SCG spirits, compared to those produced traditionally. These findings were reflected by the sensory analysis, which showed no statistically significant differences in terms of smoky and medicinal scores but a higher burnt score for SCG samples. These findings suggest the potential for creating an alternative to peated whisky that retains some of the desirable sensory characteristics, yet utilises a more sustainable raw material.