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).
Pouze odrůda Henrike se vyznačovala vysokou úrovní proteolytického rozluštění. U ostatních odrůd bylo proteolytické rozluštění velmi dobré až optimální. Amylolytické a cytolytické rozluštění bylo u všech odrůd na optimální úrovni. Vyšší obsah β-glukanů byl pouze u odrůd Advent (301 mg/l) a Streif (253 mg/l). Odrůdu Advent doporučil VÚPS pro výrobu Českého piva. Odrůda Wintmalt rozšířila možnost získat kvalitní sladovnickou surovinu i na ozimý ječmen. Dále byla registrována nesladovnická odrůda jarního ječmene Kontiki a nesladovnická odrůda bezpluchého jarního ječmene AF Lucius. V roce 2009 byly také registrovány čtyři nesladovnické odrůdy ozimého ječmene, dvouřadá odrůda Faraon a tři víceřadé odrůdy Heike, Saffron a Wendy.
PoděkováníPrezentované výsledky jsou součástí řešení výzkumného projektu NAZV MZe ČR pod identifikačním kódem QH 81056. lumn it provides a more perfect separation of analytes at a comparable time of the analysis. Even 10-fold decline in oleic acid content (C18:1c) caused probably by its autooxidation was determined in malt. The results clearly show that the representation of fatty acids in a barley caryopsis is very similar to that in malt
AcknowledgementThe presented results were obtained within the solution of the research project NAZV MA CR under the identification code QH 81056. Samples of three varieties of spring barley from 24 testing stations and two winter barley varieties from 13 testing stations were analyzed according to the standard ČSN 461100-5. The favorable course of weather in 2008 positively affected content of nitrogenous substances (11.9 % and 11.4 %) and starch (64.4 % and 63.6 %) in spring and winter barley caryopses. The occurrence of sprouted grains was minimal and the amount of the damaged grains was lower. Grain harvested in 2008 was bigger and its size was more homogenous. Portion of sieving fractions above 2.5 mm was on average 88.3 % in spring barley and 87.8 % in winter barley. 2008 was a favorable year in terms of quality.
Translated by Vladimíra Nováková
Sachambula
The polyphenol contents in barley increased several-fold during malting, and the degree of increase differed with variety. The expression of HvLac1 transcript was similar in every barley variety.
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