# Experimental Whisky Fermentations: Influence of
###### Abstract  
In addition to ethanol yield, the production of flavour congeners during fermentation is a major consideration for Scotch whisky producers. Experimental whisky fermentations can provide useful information to the industry, and this is the focus of this paper. This study investigated the impact of word pretreatments (boiled, autoclaved, filtered) on fermentation performance and flavour development in Scotch whisky distillates as an alternative to freezing word for storage. Our study showed that no significant sensorial differences were detected in low wines (first distillates), while the chemical compositions showed clear changes in increased levels of esters and higher alcohols in boiled and autoclaved word. In contrast, filtered word comprised overall lower levels of congeners. Regarding alcohol yield, all three pretreatments resulted in decreased yields. In practice, the pretreatment of word prior to fermentation requires additional process operations, while freezing requires large storage units. The pretreatments adopted in this study significantly influence the composition of the malt word used for experimental whisky fermentations, and this results in a poorer fermentation performance compared with untreated word. We recommend the use of fresh or frozen word as the best options for small-scale fermentation trials.  
wort; fermentation; flavour; spirit; whisky; congener +
Footnote †: journal: Physics Letters  
10 November 2021  
Footnote †: journal: Physics Letters  
1 Division of Engineering and Food Sciences, Abertag University, Dundee DD1 1 HG, UK; g.  
several consecutive trial fermentations. Varieties in batch or day variations, such as word gravity, free amino nitrogen (FAN), or indigenous microorganisms, can significantly influence the fermentation and overshadow other factors researched, such as the fermentation conditions or yeast strains. To date, researchers have used three different approaches to acquire malt: producing word in the lab with a nanobrewery; following standard brewing protocols, such as EBC methods [4; 11; 12; 19; 22; 24; 25; 26; 27; 28]; or obtaining a large batch of word from a local distillery and freezing it [29; 30; 31]. Nevertheless, for all three approaches, enough word from the same batch must be obtained before starting a study, and this makes extending experiments nearly impossible. Small changes in word composition can have an impact on the fermentation performance and congener production [32]. Another issue is that the microorganisms in the word change from batch to batch, impacted by cleaning, raw materials, and environmental factors [8; 33], which especially influences congener production and can act as a nuisance factor that is difficult to control. They can add congeners, as well as lower the pH, which can influence the experiment [34]. As a result, the question arose as to whether physical or thermal treatment can help to standardise word. Previous research has shown that treatments impacting the microbial nutritional composition can have a significant effect on the typical Scotch whisky flavour profiles, especially on the reduction of esters [18; 35]. However, the effect of different pretreatments on flavour and congener development has not been researched yet.  
To assess whether, and to what magnitude, the pretreatment of word impacts the fermentation performance and congener production, we explored the impact of the treatment methods for word on these factors. This paper describes the fermentation effects of word filtering, boiling, and autoclaving as alternative word treatment methods, and how they impact ethanol yield, yeast viability, congener production, and spirit flavour.