Heriot-Watt study reveals potential for reduced energy use and liquid residues in Scotch malt whisky production.
Researchers at Heriot-Watt University have found that producing a stronger alcoholic liquid before distillation could make Scotch malt whisky production more efficient. Their study suggests this could cut energy use and carbon emissions by up to 16% for every litre of pure alcohol produced, while also reducing liquid residues.
The study, led by Dr Shiwen Zhuang from the university’s International Centre for Brewing and Distilling, measured how increasing wash strength from the industry standard of around 8% alcohol by volume (ABV) to between 10% and 14% ABV could affect efficiency. Wash is the liquid created after yeast converts sugars in wort into alcohol. This beer-like wash then proceeds to the wash still for initial distillation, concentrating alcohol and refining flavours.
Using a model reflecting real-world fermentation and traditional two-pot distillation, researchers found that boosting wash strength to 14% ABV could reduce pot ale volumes by 55%. Pot ale is the nutrient-rich liquid remaining after the first distillation. Spent lees, from the second distillation, could also decrease by over 30%, significantly lowering overall liquid residues.
These findings support the Scotch whisky industry’s pursuit of net zero targets and efforts to improve efficiency while maintaining production. Dr Shiwen Zhuang, Assistant Professor at the International Centre for Brewing and Distilling, stated: “This study highlights the potential environmental and operational benefits of stronger wash. These benefits could be achieved in different ways. Existing distilleries may be able to increase output without expanding fermentation capacity, while new or growing distilleries could produce the same amount of whisky using smaller equipment and lower processing volumes.”
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Dr Jane White, Assistant Professor and co-author at Heriot-Watt’s International Centre for Brewing and Distilling, identified potential economic benefits. She said: “The study also identified potential economic benefits. Lower volumes of pot ale and spent lees could reduce handling, transport and treatment costs, while maintaining the concentration of valuable materials that could be recovered and reused from these residues.”
Challenges for widespread adoption include potential new mashing approaches for higher fermentable sugars and further study on yeast performance, flavour, and the wider production process. The research was published in the Journal of the Institute of Brewing by Dr Shiwen Zhuang, Dr Jane White, and Professor Chris Boulton.
This research reflects Heriot-Watt University’s commitment to the resilience and sustainability of the brewing and distilling sector through its proposed Centre for Brewing and Distilling (CABD). The Centre aims to unite industry, researchers, and students to test new technologies, enhance resource efficiency, and develop necessary skills. Heriot-Watt is now building on this with a new PhD project, validating predicted savings and investigating stronger fermentation’s impact on spirit quality, supporting the Scotch whisky sector’s net zero journey.
