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Matoulkova D.,Research Institute of Brewing and Malting | Kosar K.,Research Institute of Brewing and Malting | Sigler K.,Academy of Sciences of the Czech Republic
Journal of the American Society of Brewing Chemists | Year: 2012

A modified de Man-Rogosa-Sharpe (MRS) medium suitable for easy, fast, and specific detection of beer-spoilage bacteria Pectinatus spp. from beer and brewery swab samples was developed. It contains readily commercially available MRS broth, cysteine hydrochloride, and sodium thioglycolate as compounds lowering the redox potential of the medium, Tetra (a mixture of tetrahydroiso-α-acids) and 2-phenylethanol as the specificity-ensuring components, and bacteriological agar, which prevents medium oxidation during sample manipulation and transport. Tests with beer and brewery isolates of Pectinatus frisingensis, P. cerevisiiphilus, P. haikarae, Lactobacillus brevis, L. paracasei, L. plantarum, Lactococcus lactis, Pediococcus damnosus, and brewery strains of Saccharomyces pastorianus and S. cerevisiae showed that the medium does not inhibit the growth of Pectinatus spp. yet suppresses the growth of other beer- and brewery-contaminating microorganisms, which, thus, do not interfere with Pectinatus determination. The characteristic and easy-to-detect snake-like motile cells of Pectinatus spp. appear after a 24-to-48 hr cultivation of samples in MRS medium with Tetra. © 2012 American Society of Brewing Chemists, Inc. Source


Matoulkova D.,Research Institute of Brewing and Malting | Kosar K.,Research Institute of Brewing and Malting | Slaby M.,Research Institute of Brewing and Malting | Sigler K.,Academy of Sciences of the Czech Republic
Journal of the American Society of Brewing Chemists | Year: 2012

We investigated the incidence and species distribution of Pectinatus species in brewery bottling halls. A total of 11 bottling lines in 10 different brewery plants were screened for the presence of Pectinatus. Using modified deMan Rogosa Sharpe (MRS) medium, 2,405 samples were collected from the conveyor belt before the monoblock and in its outlet, from the monoblock construction, filler, and crown-cork machine, and from the floor. Pectinatus was found in all of the breweries regardless of their size, output of beer, type of beer, bottling line capacity and rate, bottling and crown-cork machine construction, type of beer pasteurization, cleaning, and monoblock design. Using species-specific PCR, the presence of P. frisingensis and P. cerevisiiphilus was determined. P. frisingensis was the most frequently detected species since it was detected in the filling area in nine breweries, while P. cerevisiiphilus was detected in only one brewery plant. © 2012 American Society of Brewing Chemists, Inc. Source


Belakova S.,Research Institute of Brewing and Malting | Benesova K.,Research Institute of Brewing and Malting | Caslavsky J.,Brno University of Technology | Svoboda Z.,Research Institute of Brewing and Malting | Mikulikova R.,Research Institute of Brewing and Malting
Food Control | Year: 2014

In 2008-2011, the occurrence of deoxynivalenol (DON), zearalenone (ZON), T-2 toxin (T-2), and HT-2 toxin (HT-2) was studied in 325 malting barley samples collected from various regions of the Czech Republic. The highest occurrence of fusarium mycotoxins was recorded in crop 2009 (2213.5, 59.4 and 145.0μg/kg for DON, ZON and ∑T-2, HT-2, respectively). Only one measured value exceeded the maximum allowable limit for DON set by the European Union.The validated method of high-performance liquid chromatography coupled with mass spectrometry was used for the analysis of the above mentioned toxins. Limits of detection were 1.5μg/kg for DON, ZON and HT-2 and 0.3μg/kg for T-2, the limits of quantification were 5.0μg/kg for DON, ZON and HT-2 and 1.0μg/kg for T-2. © 2013 Elsevier Ltd. Source


Mikyska A.,Research Institute of Brewing and Malting | Krofta K.,Hop Research Institute
Journal of the Institute of Brewing | Year: 2012

Changes in the content and composition of hop secondary metabolites during storage are reflected in beer quality and in the economics of beer production. A 12-month storage experiment with T90 pellets of four hop varieties showed different dynamics of hop aging in relation to both storage conditions and hop variety. Negligible effects on the α- and β-acids were detected during storage without air access at +2°C. Storage at +20°C resulted in a final loss of 20-25% α-acids, but the content of β-acids did not change significantly. Large decreases in α-acids (64-88%) and in β-acids (51-83%) were found in hops stored with access to air at +20°C. The rate of decline accelerated markedly after 6 months of storage. In terms of hop resin changes, Premiant and Sládek were the most and the least stable varieties, respectively. After 12 months, the content of the total polyphenols and flavonoids decreased by 30-40% and by 20-30%, respectively, irrespective of storage conditions. The rate of decline accelerated strongly after 6 months. The DPPH (1,1-diphenyl-2-picrylhydrazyl) antiradical potential decrease was significant only in hops stored under aerobic conditions. The depletion was 9-25% after 1 year; Saaz was the most stable variety. © 2012 The Institute of Brewing & Distilling. Source


Obruca S.,Brno University of Technology | Marova I.,Brno University of Technology | Snajdar O.,Brno University of Technology | Mravcova L.,Brno University of Technology | Svoboda Z.,Research Institute of Brewing and Malting
Biotechnology Letters | Year: 2010

Waste rapeseed oil is a useful substrate for polyhydroxyalkanoates (PHA) production employing Cupriavidus necator H16. In fed-batch mode, we obtained biomass and PHA yields of 138 and 105 g l-1, respectively. Yield coefficient and volumetric productivity were 0. 83 g PHA per g oil and 1. 46 g l-1 h-1, respectively. Propanol at 1% (v/v) enhanced both PHA and biomass formation significantly and, furthermore, resulted in incorporation of 3-hydroxyvalerate units into PHA structure. Thus, propanol can be used as an effective precursor of 3-hydroxyvalarete for production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer. During the fed-batch cultivation, propanol concentration was maintained at 1% which resulted in 8% content of 3-hydroxyvalerate in copolymer. © 2010 Springer Science+Business Media B.V. Source

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