Anti-bacterial activity of lysozyme in pitching yeast and effect of lysozyme on yeast fermentation

Lysozyme has antibacterial activity against Gram-positive bacteria and has no activity against yeast. As such, lysozyme can be used for the specific inhibition of beer spoilage bacteria. After all, the most frequently identified beer spoilage bacteria are lactic acid bacteria and brewers’ yeast is the culture used for the fermentation. Hen egg white lysozyme (300 mg/L) is tested for the antibacterial activity against four described Gram-positive beer spoilage bacteria in industrial pitching yeast and in industrial beer with refermentation in the bottle. The influence of industrial pitching yeast treated with lysozyme on the fermentation performance is also studied

Exploration of matrix-assisted laser desorption ionization-time of flight mass spectrometry as a fast identification tool for beer spoilage bacteria

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2D separation and profiling of complex oligosaccharide mixtures

Oligosaccharides present in various natural sources can contain different linkages, susbstitutions and building blocks with the same mass. Oligosaccharide mixtures often contain these isomeric and isobaric structures, which causes their complexity. These components are difficult to separate and analyze with conventional analytical methods. The technique described below was developed to obtain a higher resolution

Spectrum of polysaccharides degradation products of ales and lager beers

The saccharide spectrum, as a distribution of fractions of different molecular mass, of sixteen beers was determined by ultracentrifugation using filters with cut-offs of 1, 5, 10 and 50 kDa. The saccharide concentrations in the filtrates were determined by density measurements. The saccharide composition was examined through HPAEC-PAD. The results were compared with the values of classic features of beers. The newly developed method provides additional information of the beers and is a simple and fast tool for exploring the effect of the saccharide spectrum on the industrial characteristics. The results revealed that similar top fermentation beers and similar lager beers have different saccharide spectra

Monitoring the purity of industrial starter cultures using MALDI-TOF MS

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Plant-based beverages as good sources of free and glycosidic plant sterols

To address the ever-growing group of health-conscious consumers, more and more nutritional and health claims are being used on food products. Nevertheless, only very few food constituents, including plant sterols, have been appointed an approved health claim (European Commission and Food and Drugs Administration). Plant sterols are part of those limited lists of approved compounds for their cholesterol-lowering properties but have been praised for their anti-inflammatory and anti-carcinogenic properties as well. Despite this indisputable reputation, direct quantitative data is still lacking for naturally present (conjugated) plant sterols in beverages. This study aimed to fill this gap by applying a validated extraction and UPLC-MS/MS detection method to a diverse range of everyday plant-based beverages. B-sitosterol--D-glucoside (BSSG) showed to be by far the most abundant sterol in all beverages studied, with concentrations up to 60–90 mg per 100 mL in plant-based milk alternatives and fresh fruit juices. Ergosterol (provitamin D2) could be found in beers (0.8–6.1 g per 100 mL, from the yeast) and occasionally in juices (17–29 g per 100 mL). Overall, the results demonstrated that the concentrations of water-soluble sterol conjugates have been underestimated significantly and that specific plant-based beverages can be good, low-fat sources of these plant sterols

Exploration of matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) as a fast identification tool for beer spoilage bacteria

Beer spoilage induced by bacteria is a common problem in the brewing industry and has a great impact on the brewing economy. The present study aims to develop a quick, accurate and inexpensive method to detect and identify beer spoilage bacteria. To achieve this, an extensive database comprising about 6500 MALDI-TOF MS-profiles including more than 260 accurately identified contaminants and beer spoilage isolates was built. The 260 isolates represent all commonly encountered spoilage bacteria with a focus on lactobacilli, acetic acid bacteria and some anaerobes. The profiles revealed culture-independent species-specific biomarker peaks for all spoilage species, allowing straightforward identification of novel isolates. The final aim of the present study is to detect and identify spoilage bacteria in a sample with no or minimal culture steps