Yeast is one of only three ingredients allowed when making single malt and is responsible for converting sugar into alcohol during fermentation. Once the barley has been malted, mashed, and mixed with warm water, the resulting liquid—called wort—is transferred to large fermentation vessels known as washbacks. Then, yeast is added to start the fermentation.
The yeast eats the natural sugars in the wort and converts them into alcohol. The process lasts from two to five days and results in an un-hopped, un-pasteurised beer called the "wash," around 6–8% ABV. This wash is then distilled to concentrate the alcohol and refine the flavour.
But as well as producing alcohol, the yeast also creates a variety of flavour compounds like esters, aldehydes, and other congeners. These compounds significantly influence the aroma and taste of the finished whisky. Distilleries select specific strains of yeast to develop unique flavour profiles in their products. Ultimately, yeast is not only vital for fermentation but also for shaping the distinctive character of each whisky.
Some distilleries outsource this stage to breweries but at Kinglake Distillery brewing is at the core of creating a uniquely rich and luxurious malt. Most distilleries keep their fermenters tightly controlled however our incredible rural location means we can leave ours open to the air and allow natural yeasts and pollens to add incredible complexity to the wash.