Transfer of Fusarium mycotoxins and 'masked' deoxynivalenol (deoxynivalenol-3-glucoside) from field barley through malt to beer.

摘要

The fate of 5 Fusarium toxins during malting and brewing processes was investigated: deoxynivalenol (DON); total of 15- and 3-acetyl-deoxynivalenol (ADON); HT-2 toxin (HT-2) representing the main trichothecenes; and zearalenone (ZON). 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 (only DON and ZON are currently regulated). 2 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 HPLC coupled with tandem 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 barley grains (the first step in the malting process) apparently reduced Fusarium mycotoxin levels to below their quantification limits (5-10 mug/kg), 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. Concn. 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 approx. 5:1 in both sample series. When calculating mass balance, no significant changes were observed during brewing for ADON. The content of DON and ZON slightly decreased by a max. of 30%. Only traces of HT-2 were detected in some processing intermediates (wort after trub removal and green beer).