While beer is considered an unfavorable substrate of growth for many microorganisms, there are a limited number of bacteria and yeasts, which are capable of growth and may spoil beer especially if it is not pasteurized or sterile-filtered as craft beer. A new study published in the Journal of Food Science tracks lactic acid bacteria (LAB), which are well-known as the main spoilage agents, inside a brewery and during the craft beer production process.
The researchers collected and analyzed samples from indoor air and work surfaces in the brewery under study, in addition to samples of commercial active dry yeasts, exhausted yeasts, yeast pellet (obtained after mature beer centrifugation), and spoiled beers in order to identify the contaminant LAB species and the source of contamination. The researchers found Lactobacillus brevis in a spoiled beer and in a commercial active dry yeast. They also found other LAB species and bacteria ascribed to Staphylococcus sp., Enterobaceriaceae, and Acetobacter sp. in the brewery.
The researchers concluded that the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique in combination with a culture-dependent method applied along the craft beer production process were efficient in identifying the beer spoilage bacteria and the source of contamination. They confirmed the importance of a specific and efficient sanitization plan, based on the application of hygiene and good manufacturing practices, which are often the most effective methods for managing microbiological risk.
