The Influence of Yeast on the Oxidative Stability of Beer

Beer flavour deteriorates and the extent of this deterioration is often referred to as flavour stability. Producing beer which is more stable allows brewers to optimise their supply chains, whilst ensuring the consumer receives a quality product. There are several control points in the production of beer where flavour stability may be influenced. Fermentation is one such point and the influence of yeast is key, although poorly understood. At a time when brewers are looking beyond traditional brewing yeast strains, greater insight into the yeast traits which contribute to flavour stability may help in future yeast strain selection. Knowledge of the key phenotypes may also lead to improved yeast handing or monitoring practices. In this study 100+ proprietary yeast strains were characterised according to their sensitivity to oxidative stress (via menadione and hydrogen peroxide). Strains were then selected for fermentation screening and the oxidative stability followed using electron paramagnetic resonance (EPR). The EPR oxidative stability assay is one method that brewers are utilizing to optimize their process with regard to flavour stability without the time requirements of stored aging and sensory testing of beer. This study shows the change over time of the assay response and discusses the potential yeast traits that may be responsible.