Yeast works its magic by fermenting malt sugar to alcohol and carbon dioxide. Little was known about its properties until well into the 19th century so until then the fermentation process could not be controlled. As yeast expands up to 3 or 4 times its size during the main fermentation process, Bitburger also made a tidy profit selling excess yeast as baker's yeast in the past.
The brewery first began using bottom-fermenting yeast in 1879. This works at temperatures between 4 and 9°C, while top-fermenting yeast works best between 15 and 25°C. After fermentation, top-
fermenting yeast rises to the surface, whereas bottom-fermenting yeast is deposited at the bottom. To this day, Bitburger still only uses bottom-fermenting yeast during the fermentation process.
Around this time, scientists such as Louis Pasteur and Emil Christian Hansen made groundbreaking discoveries in yeast research. This new-found knowledge meant breweries could actually control the fermentation process – with a positive effect on the taste and lightness of the beer. The Research and Teaching Institute for Brewing (VLB) in Berlin, Germany cultivated its first special yeast strain for Bitburger Pils in 1913. And it’s still one of four main elements that influence the taste of Bitburger beer today.