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.