Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, the scientific journal of the Mendel University in Brno, Czech Republic

Hulless oats and hulless barley are highly valued for their excellent nutritional attributes and are increasingly being promoted in human nutrition. However, special attention should be paid to the risk of their contamination by Fusarium mycotoxins, as the rate of mycotoxin reduction during processing could be much lower than that for hulled cereals. In the present study, mycotoxin contamination of two cultivars, each of hulless oats and barley suitable for food purposes were studied in a 3-year field trial established in two contrasting environments. The contents of the mycotoxins regulated by law (deoxynivalenol and zearalenone) were low, and the present legal limits for their maximum content in unprocessed cereals were far from being exceeded. The mycotoxins most frequently occurring in hulless barley were enniatins (enniatin B, enniatin B₁ and enniatin A₁), beauvericin and nivalenol; hulless oats most frequently contained the HT-2 and T-2 toxins, beauvericin and enniatin B. The contents of enniatins and nivalenol were higher in barley than in oats. Close, positive relationships between the contents of the individual enniatins and between enniatins, beauvericin and nivalenol were observed, which implies that co-exposure could enhance the toxic potential of these mycotoxins through synergistic effects. The results highlight the need to pay more attention to the occurrence of enniatins, beauvericine and nivalenol in hulless oats and barley used for food purposes.

Barley is a good source of dietary fibre, vitamins, and minerals. Moreover, it is a source of polyphenols, which recently have been studied for their antioxidant properties. Barley generally is not eaten in its raw form, and the necessary processing influences the polyphenol content. This study evaluated the content of polyphenol compounds and antioxidant activity before and after thermal treatment typical for that carried out in households (i.e., boiling and subsequent microwave heating). Six genetic materials of hull-less barley were chosen for this study. The results showed that all tested barley genotypes were good sources of polyphenols. The studied thermal processes led to certain reductions in polyphenol content. The antioxidant activity of soluble phenolic compounds and the effects of heat treatment, as analysed by Trolox equivalent antioxidant activity (TEAC) and 2,2-diphenyl-1-picrylhydrazyl assay (DPPH) methods, differed. In the case of the DPPH method, the boiling and subsequent microwave heating indicated growth in antioxidant activity for almost all genotypes. When using the TEAC method, the results were not so clear, as the indicated activity both increased and declined. In the case of insoluble polyphenols, the antioxidant activity decreased for almost all genotypes regardless of the measurement method used.