Potencijal biosinteze aflatoksina B1 u različitim vrstama Triticum spp. / Potential biosynthesis of aflatoxin B1 in different species of Triticum spp.

The presence of fungi and mycotoxins in food presents a multiple risk, both from the aspect of food safety and from the aspect of global trade. The frequency and incidence of mycobiota on common wheat and spelt grains samples collected in the region of Vojvodina were determined after harvest during the three-year period (2015-2017). The research covered the identification and characterization of 38 A. flavus isolates using a polyphase approach including classical microbiological and molecular methods. Testing the A. flavus isolates for AFB1 biosynthesis, it was found that two isolates originating from wheat grains possess the aflatoxigenic potential. Artificial inoculation of different Triticum species: common wheat, spelt, khorasan and hybrid wheat with toxigenic isolates was carried out in the flowering stage in order to compare the resistance of these species to the occurrence of A. flavus and the production of AFB1. The highest AFB1 level (256 µg/kg) was determined only in the dehulled spelt grains, in comparison to other species where AFB1 was not detected in dehulled grains. In order to investigate the impact of wheat hulls on development of A. flavus, including the biosynthesis of toxic fungal metabolites, physico-chemical and structural properties of different Triticum spp. hulls were characterized. The effects of different temperatures (15, 23, 30 and 37 ° C) and water activity (0.85; 0.90; 0.95 and 0.99) on AFB1 biosynthesis were examined on artificially inoculated hull-less as well as hulled spelt grains. The optimal conditions for AFB1 biosynthesis (the conditions in which the highest AFB1 yield was achieved) were temperature 30 °C and 0.99 aw in the all tested spelt samples (hull-less grain, dehulled grains and hulls). Accumulation of AFB1 was significantly higher in hull-less than in dehulled grains that implicate the protective effect of spelt hulls. Mathematical models, developed using high-significance factors such as storage temperature and water activity, can be used to predict the accumulation of AFB1 in spelt grains, which is a key step in risk assessment. By examining the influence of different levels contamination levels of spelt grain with AFB1 and comparing to the control (uncontaminated) sample, the reduction in certain technological quality parameters and the potential loss of dough properties of spelt flour with AFB1 content of 50 μg/kg and 250 μg/kg was pointed out.