Microbiological quality control at Super Bock group

: risk assessment and implementation of new molecular methodologies

Abstract

Ensuring a proper routine microbiological quality control testing in breweries is crucial for maintaining high product quality and safety. It is known that possible microbiological contaminations can occur throughout all of the brewing procedure. Bacteria and wild yeasts are some of the possible contaminants, due to their spoilage nature, that can be translated into several consequences, with a varying degree of risk. If unchecked, contaminations can lead to significant financial loss and decrease consumer confidence. This dissertation provides a critical analysis of current microbiological methodologies at Super Bock Group (SBG) company and the feasibility of enrichment media and implementation of qPCR into the routine work at the microbiology quality control laboratory. Over the period of 9 months, 57 samples, acquired throughout multiple sampling points, were considered as a positive result, synonym to the detection of CFUs in plate. Subsequently, all microorganisms were isolated and identified (phenotypic tests), of which 15 were sequenced. According with the sequencing results, it was identified some fragilities during the sampling procedure, since 21% of these were considered as false positives, microorganisms unable to develop in beer (never previously detected in breweries), and no isolate constitutes a microbiological risk (non-pathogenic, not a beer spoiler) to the process. qPCR was performed on all isolates of wild yeasts and lactic acid bacteria, which always lead to a negative result. Three external strains of spoilage microorganisms (two bacteria and one yeast) were obtained for qPCR and enrichment media testing. According with the frequency of false positives and the restrictive nature of enrichment media, the adoption more specific molecular methodologies (ex.: sequencing, other PCR systems, MALDI-TOF MS) are advised to the SBG for the proper identification of the microorganisms and distinction of the associated risk.

Date of Award	26 Jul 2023
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Fábio Emanuel Torres Oliveira (Supervisor) & Pedro Miguel Gonçalves Rodrigues (Co-Supervisor)