The cooled wort is now mixed with yeast in one of our six stainless steel washbacks. The temperature is set at a level where yeast cells can survive and produce alcohol. It takes seven days for all the sugar to be consumed. The alcohol content is now about 9.5 %, and we have a mash ready to be distilled.

We use different yeast cultures for different recipes. Sometimes, we mix two cultures to achieve the desired flavour profile. We have a distiller's yeast, which produces fruity notes and completes fermentation. This can be mixed with a Saison yeast, which produces somewhat spicier notes, with hints of cloves and plum. We adapt the yeast cultures and their flavour profiles according to the whisky style we are producing.

The yeast is supplied as dry yeast and is soaked for 15 minutes before being mixed into the wort. This yeast slurry is added to the washback once the wort is cooled to 20°C. We add 1.5 kilos of dry yeast to 5400 liters of wort. 

The fermentation proceeds for 168 hours, i.e. seven days, which is an exceptionally long time. This allows us to control the growth of the yeast. And this, in turn, produces more esters, which contributes to the fruity flavours in our distillate.

With fermentation completed, we have an alcohol content of 9-10 %, which is unusually high. This gives us fruitier flavours while at the same time lowering our energy consumption.