## 1 Introduction
Carotenoids occur in small amounts in all anatomical parts of the caryopses, mainly in embryos, and cereals are a good source of them [8]. Besides the beneficial components, cereals may contain undesirable compounds, such as mycotoxins, which can be very harmful for human health [11]. The most common mycotoxin producing fungi found on cereals belong to the genera _Fusarium_, _Aspergillus_ and _Penicillium_. The most important mycotoxins, with increasing occurrence in cereal grains in recent years, are trichothecenes such as deoxynivalenol (DON), T-2 toxin and HT-2 toxin, zeanalenone (ZEN) and fumanis [12; 13]. As reported by [PERSON] et al. [14], DON, T-2 toxin, HT-2 toxin and ZEN occur very often in cereal crops cultivated in northern temperate regions. DON is the most frequently found contaminant of oat, barley, wheat and corn throughout the world. While the type A trichothecenes (T-2 toxin, HT-2 toxin, diacetoxysicrpenol (DAS) and neosolaniol) show acute toxicity at low doses, type B trichothecenes (DON and NIV (nivalenol)) are associated with more chronic toxicity. During improper storage of cereals, ochratoxin A (OTA) and aflat are produced in grain by fungi of the _Aspergillus_ and _Penicillium_ genera. The toxic effect of mycotoxins on animals is manifested by growth inhibition and reproductive, immune and digestive disorders. OTA, a toxin most frequently found in cereals cultivated in the temperate climate zone, is potentially carcinogenic to humans [12; 13; 15]. Aflatoxins are also known for their mutagenicity and carcinogenicity, although the mechanisms of their actions remain to be elucidated [16]. The risk of mycotoxins occurrence in cereals and cereal-based products can be reduced by selecting cultivars that show resistance to fungal infestation, appropriate cultivation of the soil and applying proper care treatments during the growing season. Some of the currently available varieties provide better fungi resistance than others, but they may react differently under different growing and post-harvest conditions. In organic farming, there is a strong emphasis on cultivation procedures following the requirements of good agricultural practice, thus protecting crops against the possibility of being infested by mycotoxins producing fungi. A well-managed organic production system, through the use of diverse crop rotations, non-use of synthetic pesticides in plant protection and the appropriate fertilization management (without mineral nitrogen fertilizers), prevents the occurrence of mycotoxins related to the production [17; 18; 19; 20]. Organic agronomic systems compared to the conventional, more intensive practices, are often reported to provide crops richer in bioactive compounds such as polyphenols and carotenoids [21; 22; 23], which is known to be associated with a lower nitrogen availability as well as natural defense mechanisms of plants in the organic system [24]. However, there are also studies which do not confirm the above described effect of the agronomic system on bioactive compounds concentrations in crops, including cereal grains [25]. As the necessity for finding the best cultivars of plants for organic production is still a very important topic, the aim of this study was to investigate selected quality and safety features (phenolics and carotenoids concentrations and mycotoxin occurrence) of a number of oat and barley cultivars grown organically in a controlled field trial. Barley and oat produced in Poland is currently intended for animal feeds and malt, but also for human consumption. Therefore, the presented research on the bioactive compounds profiles and mycotoxin contamination in these cereals' grain may be of interest especially to the producers to enable them to select cultivars characterized by high quality values, which are also expected by the consumers. Moreover, these results may be a premise for further research towards developing seed production aimed at organic producers.