<p style="text-align: justify;">Prisustvo plesni i mikotoksina u hrani predstavlja višestruku opasnost, kako sa aspekta bezbednosti hrane, tako i sa aspekta globalne trgovine. Učestalost i intenzitet pojave plesni na uzorcima zrna hlebne pšenice i spelte prikupljenih u regionu Vojvodine određeni su nakon žetve tokom trogodišnjeg perioda (2015-2017). Istraživanja su obuhvatila identifikaciju i karakterizaciju 38 izolata A. flavus primenom polifaznog pristupa koji uključuje klasične mikrobiološke i molekularne metode. Ispitivanjem potencijala biosinteze AFB<sub>1</sub> izolata A. flavus utvrđeno je da su dva izolata poreklom sa zrna hlebne pšenice pokazala aflatoksigeni potencijal. Veštačka inokulacija različitih Triticum vrsta: hlebne pšenice, spelte, korasan i hibrida pšenice toksigenim izolatama izvršena je u fazi cvetanja u cilju poređenja otpornosti ovih vrsta na pojavu A. flavus i produkciju AFB<sub>1</sub>. Visok nivo AFB<sub>1</sub> (256 μg/kg) je kvantifikovan samo u zrnu spelte, dok kod drugih Triticum vrstama, zrno nije bilo kontaminirano AFB<sub>1</sub> (<LOD). Određivanjem fizičko-hemijskih karakteristika plevičastih omotača Triticum vrsta potvrđen je njihov potencijalni uticaj na rast i razvoj A. flavus i biosintezu AFB<sub>1</sub>. Efekti različitih temperatura (15, 23, 30 i 37°C) i aktivnosti vode (0,85; 0,90; 0,95 i 0,99) na biosintezu AFB<sub>1</sub> ispitani su na veštački inokulisanim uzorcima spelte sa plevičastim omotačima kao i prethodno oljuštenim zrnima. Optimalni uslovi za biosintezu tj. uslovi pri kojima je ostvaren najveći prinos AFB<sub>1</sub> bili su temperatura 30 °C i aw 0,99 u svim tipovima uzoraka (zrna spelte inkubirana bez plevičastih omotača - ZBPO, plevičasti omotači - PO i zrna nakon ljuštenja tj. oljuštena zrna - OZ). Rezultati su pokazali da je prisustvo plevičastih omotača bilo zaštitna barijera za razvoj infekcije i akumulaciju AFB<sub>1</sub> u zrnu. Matematički modeli, razvijeni primenom faktora sa visokom značajnošću kao što su temperatura skladištenja i aktivnost vode, mogu biti korišćeni u predviđanju akumulacije AFB<sub>1</sub> u zrnu spelte što predstavlja ključni korak u proceni rizika. Ispitivanjem uticaja različitih nivoa kontaminacije spelte AFB<sub>1</sub> u poređenju sa kontrolnim nekontaminiranim uzorkom ukazano je na smanjenje određenih parametara tehnološkog kvaliteta i potencijalne gubitke pecivnih svojstava speltinog brašna pri sadržaju AFB<sub>1</sub> od 50 μg/kg i 250 μg/kg.</p> / <p>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 AFB<sub>1</sub> 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 AFB<sub>1</sub>. The highest AFB<sub>1</sub> level (256 μg/kg) was determined only in the dehulled spelt grains, in comparison to other species where AFB<sub>1</sub> 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 AFB<sub>1</sub> biosynthesis were examined on artificially inoculated hull-less as well as hulled spelt grains. The optimal conditions for AFB<sub>1</sub> biosynthesis (the conditions in which the highest AFB<sub>1</sub> 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 AFB<sub>1</sub> 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 AFB<sub>1</sub> in spelt grains, which is a key step in risk assessment. By examining the influence of different levels contamination levels of spelt grain with AFB<sub>1</sub> 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 AFB<sub>1</sub> content of 50 μg/kg and 250 μg/kg was pointed out.</p>
| Identifer | oai:union.ndltd.org:uns.ac.rs/oai:CRISUNS:(BISIS)108224 |
| Date | 11 January 2019 |
| Creators | Krulj Jelena |
| Contributors | Markov Siniša, Dimić Gordana, Cvetković Dragoljub, Bodroža-Solarov Marija, Bočarov-Stančić Aleksandra |
| Publisher | Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, University of Novi Sad, Faculty of Technology at Novi Sad |
| Source Sets | University of Novi Sad |
| Language | Serbian |
| Detected Language | English |
| Type | PhD thesis |
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