Transformation of Selected Trichothecenes during the Wheat Malting Production

Abstract

The transformation of deoxynivalenol (DON), nivalenol (NIV), and their glucosides (DON3G and NIV3G) during the malting of grains of two wheat varieties was studied. The concentration of DON3G and NIV3G started to increase significantly before the concentration of DON and NIV increased. This may reflect the transformation of the parent mycotoxin forms into their glucosides due to xenobiotic detoxification reactions. After a sharp rise during the last 2 days of the process (day 6 and 7), the DON concentration reached 3010 ± 338 µg/kg in the Legenda wheat-based malt and 4678 ± 963 µg/kg in the Pokusa wheat-based malt. The NIV concentration, at 691 ± 65 µg/kg, remained the same as that in the dry grain. The concentration of DON3G in the Legenda and Pokusa wheat-based malt was five and three times higher, respectively, than that in the steeped grain. The concentration of NIV3G in the Legenda wheat-based malt was more than twice as high as that in the steeped grain. The sharp increase in the concentration of DON at the end of the malting process reflected the high pathogen activity. We set aside some samples to study a batch that was left undisturbed without turning and aeration, for the entire period of malting. The concentration of DON in the malt produced from the latter batch was 135% and 337% higher, for Legenda and Pokusa, respectively, than that in the malt produced from the batch that was turned and aerated. The NIV concentration was 22% higher in the latter batch.

Transformation of Selected Fusarium Toxins and Their Masked Forms during Malting of Various Cultivars of Wheat

“…The increase in the relative content of DON-3G and NIV-3G in the samples of malted wheat grain compared to the content of these substances in unprocessed grains demonstrates the importance of the malting process in the context of the presence of these metabolites in malt. Similar observations have been reported in previous studies [12]. The content of DON-3G in wheat grain was found to be in the range of 10-17%, while in malted wheat grain, this content was 19-55% of the DON content (depending on the wheat genotype and malting time) and stabilized between 4 and 7 days of malting.…”

“…The authors showed that during the malting process, the content of the analyzed mycotoxins increased after the process in 70% of the samples, while it should be noted that each mycotoxin was present in the barley grain at a level below 50 µg/kg, indicating a low level of grain infection with pathogen spores or a low toxicogenic potential contributing to de novo biosynthesis of the mycotoxins [26]. Based on the results presented in this paper and previous research [12], it can be concluded that there is a slower biosynthesis trend of NIV during the malting process of wheat grain as compared to that of DON, and its content in malt may slightly exceed its content in the wheat grain. However, it should be mentioned that apart from the conditions of the malting process of cereal grains, the de novo biosynthesis ability of NIV may depend on a chemotype of a pathogen strain, which may determine the biosynthesis intensity.…”

“…In our previous studies, significant increases in the contents of DON and NIV metabolites (compared to the initial stage) were found from the third, fourth, or fifth day of malting (depending on the wheat cultivar and type of analyte). On the last day of malting, the content of DON-3G increased by over 500% (Legenda) and 300% (Pokusa) compared to the grain after steeping, whereas in the case of NIV-3G, this increase exceeded 200% [12]. As in the previous studies, it was found in the experiment described here that significant increases in the content or an upward trend in the content of DON and NIV metabolites in malted wheat grain started earlier in the process than in the case of parent toxins.…”

“…An earlier study by Bryła et al reported comparable results. Upon steeping of wheat grain containing 702 µg/kg of NIV, its content decreased by 26%, while during the malting process, its content increased, reaching a level comparable to the initial content [12]. Malachova et al analyzed changes in the contents of selected toxins (including NIV) during barley grain malting.…”

“…To date, there has been limited knowledge regarding the transformation of mycotoxins during the malting process. Our preliminary work highlighted the possible hazard of secondary fungi growth during beer malting [12], while this work investigated these processes in detail. To the best of our knowledge, this study is one of the first to describe the transformation processes of mycotoxins, including their metabolites, during the malting of wheat grain.…”