From Fermented Wash to New Make Spirit: Assessing the Evolution of Flavour Characteristics of Scotch Whisky Using Lab-Scale Process Simulations

Abstract

New product development for distilled spirits frequently involves experimental trials at the laboratory scale that attempt to replicate industrial-scale production processes. This process is time-consuming and limits the number of samples that can be analysed. The aim of the present study was to conduct laboratory-scale Scotch malt whisky production experiments to determine if samples taken from earlier in the production process, that is, directly after fermentation (wash stage) or after a single distillation (low wines stage), showed similar analytical differentiation compared to samples of fresh distillates (new make spirits). Napping, a rapid sensory method, was used to assess the impact on flavour characteristics while solid-phase microextraction (SPME) gas chromatography–mass spectrometry (GC–MS) was used to analyse volatile flavour congeners. Hierarchical Multiple Factor Analysis was used to compare the product maps from samples taken at each whisky production stage and revealed a pattern of differences across the samples that could be tracked through the process. Although the flavour descriptors and volatile congeners composition changed at each stage, there were only marginal changes in the differentiation between samples, resulting in the same sample groups being found in all analyses. RV coefficients >0.90 for all analytical comparisons and >0.74 overall showed that all product maps were highly similar to each other and showed the same overall differentiation between samples. These results indicate that the analysis of fermented malt whisky wash may provide sufficient information to proceed to larger-scale industry trials, saving time and allowing a greater number of parameters to be explored.

The potential for Scotch Malt Whisky flavour diversification by yeast

“…Recent findings comparing the flavour profile of wash, low wines, and new make spirit of different yeast strains showed that the key flavour notes are stable throughout these production steps. This finding will support the development of new yeast strains by reducing the time needed for sample preparation by eliminating the need for a double distillation for early yeast screening rounds (Daute et al 2023 ). Together with the finding that congener profiling of wort by gas chromatography–mass spectrometry (GC–MS) gives comparable data to the sensory evaluation, this could further reduce the time by not requiring a sensorial evaluation of samples in early screening steps (Daute et al 2021b ).…”