This master thesis deals with monitoring of a content of deoxynivalenol, its metabolite deoxynivalenol-3-b-D-glucopyranoside and ochratoxin A in beer samples collected from retail market in the Czech Republic, Poland and Slovakia. The theoretical part describes general characteristics of mycotoxins, its transfer from field barely through malt to beer and its occurrence in beers. Malting process and brewing technology were also mentioned. Subsequently possibilities for a determination of the mycotoxins by the chromatografic and immunochemical method were presented. The experimental section describes analysis of 30 samples of beer. The analyses were conducted using ultra high-performance liquid chromatography with fluorimetric detection (UPLC/FLR) for ochratoxin A and high-performance liquid chromatography coupled with mass spectrometer (HPLC/MS) for deoxynivalenol and its metabolite. Ochratoxin A was detected in 25 of the 30 samples in concentration range of 0,6 - 82,5 ng·l-1. Deoxynivalenol was found in 24 of the 30 samples with concentration range of 2,29 - 12,57 ug·l-1 and deoxynivalenol-3-b-D-glucopyranoside was occure in 19 of the 30 samples in concentration range of 2,45 - 12,47 ug·l-1. It was also assessed the relationship between beer gushing and presence of mycotoxins in beer. No connection between the parameters has been found. Consequently it is not possible to predict beer gushing from the presence of mycotoxins.

No description available.

Mycotoxins are secondary metabolites of moulds, which attack cereals, for example barley, from which mycotoxins then get to beer. This submitted work is focused on ochratoxin A, deoxynivalenol and zearalenone, which can occur in beer. The first part of this master’s thesis consists of literary research, which describes mycotoxins in general, points out their occurrence, prevention of their formation and delivers information about their physical and chemical properties and toxicity. Furthermore, the research contains basis of malt and beer technology, the occurrence of mycotoxins in beer and raw materials for its production. The research describes changes in concentration of mycotoxins across malt and beer production. The next part deals with possibilities of determination of mycotoxins in barley, malt and beer, compares individual methods of their determination and points out many difficulties of some analyses. The experimental part of this work pursues determination of ochratoxin A, deoxynivalenol and zearalenone in different types of beer with the help of UPLC-FLR, HPLC-MS and ELISA. Instrumental techniques are validated and gathered results are compared with the results in literature. The goal of this master’s thesis is to assess the stability of ochratoxin A and deoxynivalenol in beer over time. The gained results show that there are changes in the concentration of ochratoxin A over time, nevertheless those changes show no pattern. Overall, there was a decrease in concentration in 47 % of the samples and an increase in 28 % of them. In the rest of the samples the concentration did not change. The concentration of deoxynivalenol does not change over time. One of the other goals of this thesis is monitoring of selected mycotoxins in beer. The average concentration of ochratoxin A in the samples was 39 ng/l and deoxynivalenol 9,9 g/l. Zearalenone did not occur in any of the samples when determined by liquid chromatography. All results agree with literature. Next, the thesis compares different analytical methods for determination of ochratoxin A, deoxynivalenol and zearalenone. The screening method ELISA is compared to UPLC-FLR and HPLC-MS. The determination of ochratoxin A by ELISA has shown to be time consuming, nevertheless the results responded to instrumental technique. ELISA overestimated the results of determination of deoxynivalenol in beer by 363–697 % and with zearalenone there were found false positive results.

The presented thesis deals with the issue of mycotoxins in brewing materials and beer. Attention was devoted mainly to the selected fusarium mycotoxins (deoxynivalenol, zearalenol, T-2 toxin, and HT-2 toxin) ochratoxin A and aflatoxins B1, B2, G1, and G2. The aim of the thesis was to optimize and validate analytical methods for the determination of the above mentioned mycotoxins in the brewing materials and beer. Analytes were separated using high-performance liquid chromatography with mass – spectrometric detection (HPLC-MS/MS) and ultra-performance liquid chromatography with fluorescence detection (UPLC/FLR). These analytical methods were then applied for mapping the occurrence of fusarium mycotoxins in malting barley crops in the Czech Republic and monitoring the level of contamination with mycotoxins in malting and brewing industries. In addition, experiments studying over-foaming of beer were conducted as primary gushing – over-foaming of beer – is connected, similarly as mycotoxins, with the presence of microscopic filamentous fungi in the raw materials for beer production. Studies describing in detail these methods are part of this thesis (Annex I – V). From all published results, it is evident that the occurrence of mycotoxins in cereals including barley is natural and cannot be completely prevented, not even if all conditions of correct agricultural practice are observed. It is known that some mycotoxins present in contaminated malting barley pass to the final product – beer due to their chemical and physical properties. However, the mycotoxin concentrations found do not mean any significant health risk for consumers.

In a fusion plasma, the ions have to be heated to reach fusion relevant temperatures. One possibility is to launch an electromagnetic wave in the radio frequency band into the plasma. This wave can resonate with the ions at their cyclotron frequency and hence, the method is called ion cyclotron resonance heating. If the Larmor radius is of similar length scales as the wavelength, finite Larmor radius (FLR) effects are important. This introduces additional possible wave modes. To accurately predict the heating, simulations of these additional modes can be important. In order to describe the FLR effects in simulations, this work applies a Taylor expansion to second order in the perpendicular wavenumber of the dielectric tensor. In real space, the Taylor expansion corresponds to a series of spatial derivatives. These derivatives are implemented as weak-form contributions for a onedimensional finite element method (FEM)simulation. The approach is realized in a fork of the FEMIC code, coupling plasma physics in MATLAB with the FEM solver in COMSOL. The discretization of the FEM solver is adapted using a Helmholtz filter to provide the required degree of smoothness. Our approach proves successful to simulate FLR effects within the limitations caused by the modeling choices. We compare results with an all-order FLR method, showing good qualitative agreement. This work serves as a proof of concept to describe challenges on the way towards incorporation of second order FLR effects in twodimensional simulations in FEMIC. / I ett fusionsplasma måste jonerna värmas för att plasmat ska nå temperaturer relevanta för fusion. En möjlighet är att sända in en elektromagnetisk våg i radiofrekvensbandet i plasmat. Den vågen kan sedan resonera med jonerna vid deras cyklotronfrekvens, och därför kallas metoden för joncyklotronresonansuppvärmning. Om våglängden är jämförbar med Larmorradien blir ändliga Larmorradie-effekter viktiga. Detta möjliggör ytterligare typer av vågor. Det kan vara viktigt att simulera dessa typer av vågor för att förutsäga uppvärmningen på ett träffsäkert vis. I denna masteruppsats Taylorutvecklar vi den dielektriska tensorn till andra ordningen i det vinkelräta vågtalet för att beskriva hur FLR-effekter påverkar simuleringarna. I det reella rummet motsvarar Taylorutvecklingen en serie av rumsliga derivator. Dessa derivator implementeras sedan som bidrag på svag form i en endimensionell modell som löses med den finita elementmetoden (FEM). Metoden implementeras i FEMIC-koden, som kopplar plasmafysik i MATLAB med FEM-lösaren i COMSOL. Diskretiseringen av FEM anpassas med ett Helmholtzfilter för att få en tillräckligt slät funktion. Ansatsen visar sig kunna framgångrikt simulera FLR-effekter, med vissa förväntade begränsningar. Lösningen jämförs sedan med lösningen från en metod som tar hänsyn till FLR-effekter, men som inte är baserad på en serieuteckling. Vi finner god kvalitativ överensstämmelse. Detta arbete fungerar som en prototyp och ämnar att beskriva de utmaningar som kan uppstå vid implementation av FLR-effekter den tvådimensionella axisymmetriska versionen av FEMIC.