# Experimental Whisky Fermentations: Influence of
## 3 Results
### Effect of Boiling and Autoclaving on Word Quality  
Wort boiling is a typical approach in brewing used to sterilize the word, coagulate proteins, and inactivate enzymes. This influences the congener concentrations, acidifies the word, and reduces the water [59]. In contrast, in the distilling industry, word boiling is not part of the process, as distillation is carried out after fermentation to produce the spirit. Autoclaving is, in comparison, a harsher heat-treatment method. Both treatments show similar traits, and the influence of both methods on word was investigated. The boiling of word reduced the total particle count in the word to lower than one-third, compared to the control word consisting mostly of particles around the size of 10 SSC/3 FSC, and a second group around the size of 10 SSC/30 FSC (Figure 1). Autoclaving the word had the largest impact on the primary particle count by reducing it to one-fourth, compared to the control word consisting mostly of small particles around 3 SSC/3 FSC (Figure 1). Microscopic assessment of the samples prior to assessment by flow cytometry showed that larger agglomerations of particles were present in the boiled and autoclaved word of the size of around 150 \(\upmu\)m (Figure 8). During word boiling, the proteins from the malted barley coagulate with polyphenols and form insoluble coagulates, resulting in reduced protein, amino acid, and nitrogen contents [59; 60].  
As for the filtered word, boiling and autoclaving had a negative impact on the fermentation performance (Table 1). The ABV and final CO\({}_{2}\) concentration decreased, with a loss of at least 6.2 LPA/t. There was no impact on the yeast reaching the different growth phases, only that the cumulative CO\({}_{2}\) concentrations at these points were lower, showing that the fermentation is not as efficient (Figure 2, Table 1). For Scotch whisky fermentation, the activity of \(\alpha\)-amylase, \(\beta\)-amylase, limit dextrinase, and \(\alpha\)-glucosidase during fermentation is important for the breakdown of the residual starch and a gain of high alcohol yields [10]. These enzymes would be inactivated by heat pretreatments.  
Figure 8: Example microscope pictures of non- and heat-treated word: Left, control word (CW); Right, autoclaved word (AW).  
The total particle count, after fermentation, was reduced early, ten-fold, with a clear reduction in the small particles where indigenous microorganisms are measured (Table 1, Figure 3). Additionally, more yeasts remained viable at the end of the fermentation (Table 1). By boiling/autoclaving wort, enzymes were not only deactivated, but microorganisms were also killed, reducing the competition and stress on the yeast during fermentation, in addition to preventing the pH dropping as low as in the control wort [58].  
With regard to flavour changes in the low-wine distillates (Figure 4), no significant differences could be measured. However, the consensus plot of the MFA showed that the panellists, excluding Panellist Eight, scaled the samples differently from the control (Figure 5). The samples were mostly described by more _feinty_ characteristics, such as _nearty_, _cereal_, or _sulphury_. Unexpectedly, these samples had higher peak areas for most esters, as well as higher alcohols, carbonyl, sulphides, acids, and arenes (Figures 6 and 7). During wort boiling, two main reactions influence the flavour and when congener composition takes place: the Maillard reaction and Strecker degradation. One of these compounds is 2-acetylfuran [59], which is one of the compounds that were a major factor separating the four different wort treatment conditions. In this case, the compounds produced during the wort boiling may mask the flavour of higher alcohols and esters, resulting in an overall heavier spirit character.