Spoilage of bottled lager beer contaminated with Saccharomyces cerevisiae var. diastaticus

Saccharomyces cerevisiae var. diastaticus is a feared contaminant in the brewing industry, causing super‐attenuation and deterioration in beer quality. The aim of this study was to monitor parameters of bottled lager beer contaminated with Saccharomyces cerevisiae var. diastaticus. Two bottled lagers with original extracts of 10.2 and 11.6% (w/w) were inoculated at 3 ± 1 or 300 ± 50 CFU/mL and stored at 8 or 23°C. Changes in the concentration of real extract, alcohol, turbidity, sugars and increase in 4‐vinyl guaiacol were monitored over 14 weeks of storage. The most significant changes were observed in beers stored at 23°C for both concentrations of contaminant. Cold storage at 8°C delayed indicators of spoilage associated with contamination by Saccharomyces cerevisiae var. diastaticus. © 2021 The Institute of Brewing & Distilling