## 1 Introduction  
In global agriculture, barley (_Hordeum vulgar_) holds a significant position. For years, it has consistently been ranked as the fourth most grown cereal species in the world after wheat, rice, and maize [1]. In the period 2015-2021, 60.7% of the world's production of this cereal came from Europe, making it the leading continent in terms of production volume [2]. Barley is used as malt, food, and livestock feed [3]. It contains high levels of dietary fiber, particularly soluble fractions, such as \(\beta\)-glucans and arabinoxylans, and many important vitamins, such as vitamin E and B-group vitamins [4; 5]. It is also a good source of phosphorus and manganese [6], as well as phenolic compounds, carotenoids, and other antioxidants that contribute to its health-promoting properties [7; 8]. Due to the soluble dietary fiber and bioactive compounds in barley composition, its regular consumption has the potential to contribute to the reduction of serum low-density lipoprotein cholesterol levels, to modulate gut microbiota, and to decrease postprandial blood glucose levels, thus contributing to the promotion of cardiovascular health, the prevention of diabetes, and the support of the digestive system [9; 10]. Plant secondary metabolites, including phenolic compounds, play significant roles in plant reproduction, growth, and inner protection against pests and pathogens [11]. The main groups of phenolics present in cereal grains, flavonoids and phenolic acids, are known to be free radical scavengers [12; 13]. Therefore, their consumption has been suggested to be linked to numerous health benefits, including the prevention of such non-communicable diseases as cancers and cardiovascular problems [14; 15; 16]. Carotenoids are another important group of plant phytochemicals which confer nutritional quality to cereal grains and cereal-based products [17]. They play a crucial role in photosynthesis and photoprotection in plants. For humans, carotenoids are precursors of vitamin A, which is necessary for maintaining health [18]. Neither humans nor animals are able to synthesize carotenoid compounds, so their supply from diet is necessary to reap health benefits. They are antioxidants suggested to enhance immune system functions and to play a role in the prevention of retinal degradation, liver cancer, and sunburn [19]. One of the main carotenoid compounds of barley is lutein, which is accumulated in a yellow spot of the retina in the eye and protects it from damage by absorbing UV radiation [20]. Microscopic filamentous fungi of the genera _Fusarium_, _Penicillium_, and _Aspergillus_ produce mycotoxins--secondary metabolites with strong toxicity potential [21]. Infection with these fungi can lead to a reduction in the quantity, quality, and safety of grains [22]. The most common mycotoxins include deoxynivalenol (DON); fumoniss; trichothecenes, especially T-2 toxin and HT-2 toxin; zeanalenone (ZEN); ochratoxins, especially ochratoxin A (OTA); and aflat [21; 23]. The most prevalent mycotoxins in barley are deoxynivalenol (DON) and its derivatives--3-acetyldeoxynivalenol (3-AcDON) and 15-acetyldeoxynivalenol (15 Ac-DON)--which are often associated with _Fusarium_ infections. The HT-2 and T-2 toxins are also common in barley, with the former occurring more often [24]. These trichothecenes are known for their acute toxicity, posing a high risk to health at low doses. Ochratoxin A (OTA) can also be found in barley samples, although it is less common [25]. It is produced by the genus _Aspergillus_. OTA is known for its toxic effects on the kidneys, liver, nervous system, and immune system. Moreover, its embryotoxic and teratogenic effects have been proven in many species. Ochratoxin A was classified as a possible carcinogen in humans by the International Agency for Research on Cancer in 1993 [26]. Aflatoxins are also mutagenic and carcinogenic [27]. Poor hygienic conditions during transportation and storage, wetness, heavy rains, and high temperatures promote the production of these toxins.