Reduction of deoxynivalenol, T-2 and HT-2 toxins and associated Fusarium species during commercial and laboratory de-hulling of milling oats

Abstract

Oats (Avena sativa L.) are well known for their nutritional properties but are susceptible to the growth of different Fusarium fungi resulting in mycotoxin contamination of harvested oats. In this study, oat samples from harvest years 2011 to 2017 were preselected for their suitability as milling oats for food purposes with DON contents below 1750 µg/kg. The reduction of DON, T-2 and HT-2 toxins during the commercial de-hulling process was analysed. While the average reduction for the sum of T-2 and HT-2 toxins in large oat kernels was 85%, the reduction for thin kernels was 66%. The reduction for DON was about 60% and did not differ for the two kernel fractions. In laboratory de-hulling experiments, milling oat samples and de-hulled oat kernels with known DON, T-2 and HT-2 toxin content were correlated with the associated DNA amount of Fusarium graminearum, Fusarium culmorum and Fusarium langsethiae. The reduction of the Fusarium DNA amount after de-hulling was comparable to the reduction of the associated mycotoxins. Notably, the correlation between F. langsethiae DNA amounts and the sum of T-2 and HT-2 toxin contents was R² = 0.69 in milling oats and it rose to R² = 0.85 in de-hulled oat kernels. In laboratory tests, at least one third of the initial levels of DON and the sum of T-2 and HT-2 toxins could be removed by polishing off the first parts of the outer layers; two thirds remained in the polished oat kernels. These observations indicate that de-hulling alone may not be completely sufficient to remove mycotoxin contamination in oats. These findings are of high importance in the discussion of determining legal maximum levels for DON or the sum of T-2 and HT-2 toxins in intermediate and final products.

Keywords:

• Oat milling
• Fusarium mycotoxins
• trichothecenes
• Fusarium langsethiae
• Fusarium graminearum
• DNA amount

Acknowledgements

This study was financed by H. & J. Brüggen KG, Lübeck, Germany. We thank Frans Verstraete (European Commission – Directorate General for Health and Food Safety), Dr. Matthias Herrmann (Julius Kühn-Institute), Dr. Hege Hvattum Divon (Norwegian Veterinary Institute), Dr. Christine Schwake-Anduschus (Max-Rubner-Institute), Dr. Sheryl Tittlemier (Canadian Grain Commission), Prof. Simon Edwards (Harper Adams University), Dr. Stefan Hoth (Kölln), Alexander Jess (formerly Ceereal) and Dr. Steffen Beuch (Nordsaat) for fruitful discussions. Moreover, we thank Norbert Hauf, Axel Rieck, Jutta Koth, Anne Kühne, Ewa Koziol, Sybille Plath, Stefan Umland, Frank Blosfeld, Wolfgang Heine, Sabine Hasse and Ulrike Gerth (all H. & J. Brüggen KG) for their technical assistance and Johannes Meyer for revising the manuscript.

Disclosure statement

The authors do not have any financial interests.

Additional information

Funding

This work was supported by the H. & J. Brüggen KG [no grant number].