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Tylova T.,Academy of Sciences of the Czech Republic | Tylova T.,Charles University | Flieger M.,Academy of Sciences of the Czech Republic | Olsovska J.,Research Institute of Brewing and Malting PLC
Analytical Methods

A method consisting of solid phase extraction followed by ultra-high performance liquid chromatography combined with time-of-flight mass spectrometry (UHPLC-ToFMS) has been developed for the determination of multiple-class antibiotics in influents and effluents of wastewater-treatment-plants (WWTPs). The nineteen analyzed antibiotics belong to the 5 most prescribed antibiotic classes in the Czech Republic, namely tetracyclines, macrolides, sulfonamides, fluoroquinolones, and lincosamides. The matrix-matched calibration technique with internal standard addition for each antibiotic group was employed for quantification. Two extractions employing an Oasis HLB cartridge and two injections were needed for each sample due to the different physico-chemical properties of the tested antibiotics. Prior to the extraction on the Oasis HLB SPE cartridge, the samples were adjusted to pH 4.5 and 7.5. The usefulness and versatility of the method was documented by achieving method limits of quantification up to 10 ng L-1 and recoveries >80% for most analytes. The method was used for analysis of water samples of WWTPs from 6 localities in the Czech Republic in order to reveal the occurrence of selected antimicrobial agents and assess the efficiency of WWTPs in the removal of these antibiotics. All tested samples were positive for antibiotics with concentrations ranging from 5 ng L-1 to 1290 ng L-1. Antibiotics were present in both influent and effluent water samples, which documented the poor removal efficiency of the WWTPs. © 2013 The Royal Society of Chemistry. Source

Olsovska J.,Research Institute of Brewing and Malting PLC | Kamenik Z.,Academy of Sciences of the Czech Republic | Cejka P.,Research Institute of Brewing and Malting PLC | Jurkova M.,Research Institute of Brewing and Malting PLC | Mikyska A.,Research Institute of Brewing and Malting PLC

Hops represent an important natural source of bioactive polyphenols, particularly proanthocyanidins, which can contribute to prevention of several civilization diseases, owing to their antioxidant and radical scavenging activity. We have developed a high-throughput ultra-high-performance liquid chromatography time-of-flight mass spectrometry profiling method, which can be used for monitoring of bioactive proanthocyanidins in hops. The method was applied for analysis of hops of four Czech varieties (Saaz, Sladek, Preminat and Agnus) from the 2011 crop (9 localities, 11 samples) and the 2012 crop (24 localities, 40 samples). Hop samples were extracted by acetone and the analytes were separated on the Acquity UPLC BEH Shield RP18 column. Partial validation of the method revealed a satisfactory intra-day repeatability of the method for retention times (relative standard deviation within 1.39%) as well as areas under the peaks (within 9.89%). Experimental data were evaluated using principal component analysis and cluster analysis. Significant amounts of di-, tri- and tetramer proanthocyanidins consisting of (epi)catechin and (epi)gallocatechin were found in the hop samples. The dependence of the proantocyanidin composition on both the variety and the growing locality was observed. Specifically, the traditional Saaz variety contained more frequently oligomers formed by (epi)catechin units only, whereas the varieties Premiant and Agnus produced oligomers consisting of (epi)catechin as well as (epi)gallocatechin units. The relative abundance of proanthocyanidins in studied hop varieties from the two crops, 2011 and 2012, did correspond to each other. In the further perspective, the method may also be used for prediction of qualitative marks or authenticity verification of hops. © 2013 Elsevier B.V. Source

Olsovska J.,Research Institute of Brewing and Malting PLC | Cejka P.,Research Institute of Brewing and Malting PLC | Sigler K.,Academy of Sciences of the Czech Republic | Honigova V.,Research Institute of Brewing and Malting PLC
Czech Journal of Food Sciences

The character and authenticity of the Czech beer, which has been accorded the protected geographical indication (PGI) Česke pivo by the EU, are based on specific technology and use of unique raw materials. A number of chemical and sensorial markers of the Czech beer differ from those of other lager or Pils-type beers. The majority of Czech beers contain residual (unfermented) extract. One of the most typical characteristics of Czech beers is the difference in attenuation; its long-term recorded limit value is 4.5%. Another important characteristic typical of the Czech beer is bitterness, which is mostly higher in comparison with other lagers, with the limit value at 29 EBC units. Also the colour, pH, and total polyphenol content are higher in the Czech-type beer. The limit parameters obtained by long-term monitoring were 11.8 EBC, 4.52 and 153 mg/l, respectively. Differences in amino acid and protein profiles and contents were also observed. Source

Horak T.,Research Institute of Brewing and Malting PLC | Culik J.,Research Institute of Brewing and Malting PLC | Kellner V.,Research Institute of Brewing and Malting PLC | Jurkova M.,Research Institute of Brewing and Malting PLC | And 3 more authors.
Journal of the Institute of Brewing

Esters represent one of the most important flavour groups in beer. The aim of this work was focused on the comparison of two optimized, simple, rapid and low cost methods, the solid-phase microextraction technique and the stir bar sorptive extraction technique, for the determination of beer esters, in particular isoamyl acetate, ethyl caproate, ethyl caprylate, ethyl caprate, phenylethyl acetate, ethyl laurate, ethyl myristate, and ethyl palmitate. Subsequent gas chromatographic analyses with flame ionization detection were used for the determination of these compounds. Linearity, recovery, and repeatability of these methods were compared. Working parameters of both procedures were similar and characterized by high repeatability (2.1-7.3%) and good linearity (correlation coefficient ranging from 0.9991 to 0.9999). Results obtained by these two procedures were in good correlation. © 2010 The Institute of Brewing & Distilling. Source

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