Enhanced Cultivation of Beer Spoilage Bacteria in Propagation Yeast by Enforced Yeast Suppresion

Abstract

It is enormously important to be able to detect beer spoilage bacteria during the brewing process. These bacteria have the potential, for instance, to cause turbidity, acidity, and detrimental flavor changes in the product. It is extremely difficult to detect these beer spoilage organisms, in particular in the pure yeast culture or even in the yeast crop, as their growth is suppressed by the yeast. Furthermore, these bacteria are often only present as trace contaminants. In this study, a method was developed to more reliably and more quickly detect beer spoilage bacteria in pure yeast cultures than by previous methods. A natural antibiotic called Natamax® (Danisco, Niebull, Germany), which reliably kills the yeast cells but does not affect the bacteria, was added to the yeast samples. This made it possible to detect a significantly higher quantity of beer spoilage organisms than is possible without adding this antibiotic.