Modelling Scotch malt whisky fermentations and impact of fermentation on new-make spirit character

Abstract

The establishment and development of a Scotch malt whisky fermentation model was proposed in this study. Assessment of a large dataset containing 364 malt-based fermentations concluded that the 4-parameter logistic model was the most robust and useful regression to model apparent extract decline during fermentation. The application of this model to fermentation parameters at the Glenmorangie and Ardbeg distilleries demonstrated that the process was consistent over a three year period and that changes to raw materials such as barley varietal had no impact upon fermentation performance. The temporary use of dried yeast at the distillery demonstrated that lack of in-line mixing and other infrastructure meant that fermentations ended incomplete and were also lacking in consistency, though minimal impact on the congener content of new-make spirit was shown. Laboratory trials involving high-gravity, novel yeasts. and exogenous bacterial cultures demonstrated significant changes to the fermentation models produced. This outlined methods for innovation with in the Scotch malt whisky sector by producing different new-make spirit characteristics and flavours. Through modelling changes made by the use of novel raw materials or processing, the fermentation profile for Scotch malt whisky can be changed, adapted and controlled in order to influence the flavour of new-make spirit and control consistency.