Beer is, according to its properties, considered as microbiologically safe beverage. However, there are numerous reported events of beer spoilage due to the presence of microorganisms, which are a big problem in the brewing industry and reason for important economic losses. Beer spoilers belong to groups of Gram-positive, Gram-negative bacteria and wild yeasts and their presence can lead to beer turbidity, acidity and unwanted flavour. With the increased popularity of unpasteurized, nonalcoholic and low-alcoholic beers, beer-spoilage organisms present even greater problem for the brewing industry. Effective problem solution therefore demands quick and reliable identification of beer spoilers to species and/or strain level. However, bacterial identification in most laboratories is still carried out by traditional methods such as incubation on culture media and subsequent characterization through biochemical and other tests, which are labour-intensive and very time-consuming tasks. This increases storage expenses and the need for bigger storage capacity. One of the approaches for quick microbiological identification is the implementation of MALDI-TOF MS (matrix assisted laser desorption/ionization time-of-flight mass spectrometry) instrument into standard microbiological practice. The thesis presents main beer spoilers and their resistance to hop compounds as the key factor for their growth in beer. It also presents microbiological identification by MALDI-TOF mass spectrometry and compares it with the standard methods in the brewing microbiological laboratory.
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