Improved detection of beer-spoilage bacteria: validation of the NBB-C®-enrichment method

Beer spoilage is mainly caused by a limited group of bacteria, including Levilactobacillus brevis, Fructilactobacillus lindneri, and Pediococcus damnosus. Detection is essential for beer quality control. Among the microbiological tools used by breweries, enrichment in Nutrient Media for Beer-Spoiling Bacteria (NBB-C®) is based on European Brewery Convention analytical procedures, EBC ANALYTICA analytical methods; however, in our accredited method (MI LMB 01-2021), the standard 14-day incubation is modified to 7 days to provide faster results suitable for routine brewery monitoring. This study aimed to validate the modified EBC ANALYTICA 4.3.1.4 Enrichment, 2011 method using NBB-C® media by determining its probability of detection (POD) and limit of detection using pasteurized lager beer as a test matrix. For the first time, POD curves with 95% confidence intervals were estimated for L. brevis, F. lindneri, and P. damnosus. The results provided an objective and quantitative performance evaluation of the modified NBB-C®-enrichment procedure, supporting its suitability for International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) 17025-compliant testing in brewing laboratories.