Statistical evaluation of beer spoilage bacteria by real-time PCR analyses from 2010 to 2016

Abstract

A total of 13,802 samples over seven years were investigated using real-time PCR for the presence of beer spoilage bacteria, providing a rare large-scale overview of the incidence of individual species. At the same time, the isolation site (early stages of the brewing process = type I and late stages = type II) and the type of contaminated beer and intermediate products (bottom-fermented or top-fermented) were evaluated using chi-squared analysis. The most frequently occurring species were Lactobacillus brevis (7 year average 41.9%), Lactobacillus (para-)casei (10.4%) and Lactobacillus backii (9.5%). L. (para-)casei was found at significantly higher rates in the early stages of the brewing process, whereas Lactobacillus lindneri, the Lactobacillus [L. (para-)plantarum and L. coryniformis] and the Pectinatus (P. cerevisiiphilus, P. frisingensis and P. haikarae) groups and Megasphaera cerevisiae predominated in the later stages and in package (significance level 95%). On a significance level of 95%, Pediococcus damnosus, M. cerevisiae and L. lindneri together with the Pectinatus and Lactobacillus groups grew predominantly in bottom fermented samples. L. brevis, in contrast, was found most frequently in top fermented beers. Copyright © 2018 The Institute of Brewing & Distilling