The fate of five Fusarium toxins--deoxynivalenol (DON), sum of 15- and 3-acetyl-deoxynivalenol (ADONs), HT-2 toxin (HT-2) representing the main trichothecenes and zearalenone (ZON) during the malting and brewing processes--was investigated. In addition to these 'free' mycotoxins, the occurrence of deoxynivalenol-3-glucoside (DON-3-Glc) was monitored for the first time in a beer production chain (currently, only DON and ZON are regulated). Two batches of barley, naturally infected and artificially inoculated with Fusarium spp. during the time of flowering, were used as a raw material for processing experiments. A highly sensitive procedure employing high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was validated for the analysis of 'free' Fusarium mycotoxins and DON-conjugate in all types of matrices. The method was also able to detect nivalenol (NIV), fusarenon-X (FUS-X) and T-2 toxin (T-2); nevertheless, none of these toxins was found in any of the samples. While steeping of barley grains (the first step in the malting process) apparently reduced Fusarium mycotoxin levels to below their quantification limits (5-10 microg kg(-1)), their successive accumulation occurred during germination. In malt, the content of monitored mycotoxins was higher compared with the original barley. The most significant increase was found for DON-3-Glc. During the brewing process, significant further increases in levels occurred. Concentrations of this 'masked' DON in final beers exceeded 'free' DON, while in malt grists this trichothecene was the most abundant, with the DON/DON-3-Glc ratio being approximately 5:1 in both sample series. When calculating mass balance, no significant changes were observed during brewing for ADONs. The content of DON and ZON slightly decreased by a maximum of 30%. Only traces of HT-2 were detected in some processing intermediates (wort after trub removal and green beer).

Since deoxynivalenol (DON), the main representative of Fusarium toxic secondary metabolites, is a relatively common natural contaminant in barley, its traces can be detected in many commercial beers. Our previous study reporting for the first time the occurrence of relatively high levels of DON-3-glucoside (DON-3-Glc) in malt and beer prepared from relatively "clean" barley (semiscale experimental conditions) induced a follow-up investigation focused on this DON conjugate in commercial beers. The current survey involving in total 176 beers, representing different brands, and collected at various markets, has documented a ubiquitous occurrence of DON-3-Glc in this product. Its levels even exceeded that of free DON in some samples; the highest level found was 37 microg/L. In addition to glucosylated DON, its acetylated forms (ADONs) were also common contaminants in most of the beers. Generally, stronger beers (higher alcohol content) tended to contain higher levels of DON and its conjugates. No distinct relationship between the contamination of malt and beer was observed in samples collected from several breweries. Attention was also paid to comparison of data on malts obtained by LC-MS/MS and ELISA DON-dedicated kits. The latter provided apparently higher levels of DON, the most distinct difference being observed for malts processed at higher temperatures (caramel and roasted malts). The nature of this phenomenon has not yet been explained; in addition to cross-reacting species, other factors, such as the higher content of dark pigment, can also be the cause.

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Ambient mass spectrometry has been used for the analysis of strobilurin residues in wheat. The use of this novel, challenging technique, employing a direct analysis in a real time (DART) ion-source coupled with a time-of-flight mass spectrometer (TOF MS) and a desorption electrospray ionization (DESI) source coupled with a linear ion trap tandem MS (LIT MS(n)), permitted a direct screen of the occurrence of target fungicides in treated grains in less than 1 min. For quantification purpose by DART-TOF MS, an ethyl acetate extract had to be prepared. With the use of a prochloraz as an internal standard, the performance characteristics obtained by repeated analyses of extract, spiked at 50 microg kg(-1) with six strobilurins (azoxystrobin, picoxystrobin, dimoxystrobin, kresoxim-methyl, pyraclostrobin, and trifloxystrobin), were in the following range: recoveries 78-92%, repeatability (RSD) 8-15%, linearity (R(2)) 0.9900-0.9978. The analysis of wheat with incurred strobilurin residues demonstrated good trueness of data generated by the DART-TOF MS method; the results were in a good agreement with those obtained by the conventional approach, i.e., by the QuEChERS sample handling procedure followed by identification/quantification employing high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Tandem mass spectrometry using DESI-LIT MS(n) provided a sufficient number of product ions for confirmation of the identity of azoxystrobin and pyraclostrobin in incurred wheat samples.

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