The German purity law sets the German brewing industry narrow limits during beer production. The allowable raw materials are malt, water, hop and yeast. Therefore only the operating parameters such as temperature, time, pH and pressure are at the breweries command to control the processes. Due to basic research in enzyme reactions, the degradation processes, and the influencing factors, the brewing process was optimized and accelerated. Of particular importance is the growth of ever more qualified raw materials, as well as the selection and specification of sub- and top-fermenting yeast strains.