The Impact of All Grains In Methodology on the efficiency and quality of Scotch Whisky using Malted Rye and Malted Barley

All Grains In processing is commonly used during the production of grain whisk(e)y and is characteristic of some regional products such as Bourbon. For production of Scotch whisky, All Grains In is rare but of increasing interest for the potential to introduce novel compositional characteristics and to potentially improve process efficiency. All Grains In likewise offers opportunities for raw material innovation, for instance using high proportions of grain which is associated with issues of filtration following traditional processes or for a heavily comminuted grist. The present research establishes the impact of a Grains In approach when using a grist of malted barley and malted rye at varying proportions. Wort was produced under a range of mashing temperatures, mash bills and milling regimes and fermented under either filtered or Grains In conditions. Wort and wash samples were monitored for key indicators of processing efficacy and product quality: specific gravity, free amino nitrogen, ethanol yield/yeast sugar uptake, enzyme breakdown, wash polyphenolic & phenolic material and wash aroma volatile compounds. Findings indicated substantial differences of wort/wash quality between filtered and All Grains In protocols. Of key interest, wash produced using All Grains In methodology resulted in greater ethanol yield, elevated residual FAN content and a reduction in enzymatic breakdown as compared to traditional filtered processing. Although further research is required, the findings of this study highlight a potential role for All Grains In processing for the production of Scotch malt whisky possessing characteristics distinct to similar products derived from filtered processes.