Quantitative PCR (qPCR) for estimating the presence of Fusarium and its mycotoxins in barley grains.

Members within the Fusarium sambucinum species complex (FSAMSC) are able to produce mycotoxins, such as deoxynivalenol (DON), nivalenol (NIV), zearalenone (ZEN) and enniatins (ENNs) in food products. Consequently, alternative methods for assessing the levels of these mycotoxins are relevant for quick decision-making. In this context, qPCR based on key mycotoxin biosynthetic genes could aid in determining the toxigenic fungal biomass, and could therefore infer mycotoxin content. The aim of this study was to verify the use of qPCR as a technique for estimating DON, NIV, ENNs and ZEN, as well as Fusarium graminearum sensu lato (s.l.) and F. poae in barley grains. For this purpose, 53 barley samples were selected for mycobiota, mycotoxin and qPCR analyses. ENNs were the most frequent mycotoxins, followed by DON, ZEN and NIV. 83% of the samples were contaminated by F. graminearum s.l. and 51% by F. poae. Pearson correlation analysis showed significant correlations for TRI12/15-ADON with DON, ESYN1 with ENNs, TRI12/15-ADON and ZEB1 with F. graminearum s.l., as well as ESYN1 and TRI12/NIV with F. poae. Based on the results, qPCR could be useful for the assessment of Fusarium presence, and therefore, provide an estimation of its mycotoxins' levels from the same sample.

Fate and Behavior of Field-Applied Pesticides during Malting and Mashing Processes.

The present work aimed to study the fate of field-applied pesticides during malting and mashing processes. Twenty-four field-collected barley samples were subject to micromalting followed by lab-scale mashing to investigate the carryover of residual pesticides from barley to malt and then from malt to sweet wort. The citrate-buffered QuEChERS sample preparation method was adapted for simultaneous determination of 57 pesticide residues in grain, malt, spent grains, and sweet wort samples using ultra-performance liquid chromatography coupled with tandem mass spectroscopy (UPLC-MS/MS). Residues of four fungicides (fenpropimorph, pyraclostrobin, tebuconazole, and trifloxystrobin) and two insecticides (chlorpyrifos and pirimiphos-methyl), frequently found in the barley samples, were investigated in detail in this study. The carryover percentages of these pesticides to malt, against the concentration of residues in barley grain, ranged from 22% for pirimiphos-methyl up to 78% for fenpropimorph. The results confirm a general rule that residues of pesticides with log P values >2 remain on the malt, but it was found that their transfer potential is more related to its individual physical-chemical properties but does not much correlate to their log P values. In the second part of the study, a noticeable carryover from malt to sweet wort was observed for pyraclostrobin, fenpropimorph, and tebuconazole residues, and these values ranged from 2 to 15%. Moreover, the analysis of pesticide residues in spent grain after mashing revealed that the spent grain samples contain on average once as much pyraclostrobin and tebuconazole residues as the original malt. It was concluded that (1) pyraclostrobin and tebuconazole residues could be incorporated into or associated with macromolecules in barley grain to form "hidden" (bound) forms, and (2) the parent compounds are subsequently released from their hidden forms during mashing.

Wild rice (O. latifolia) from natural ecosystems in the Pantanal region of Brazil: Host to Fusarium incarnatum-equiseti species complex and highly contaminated by zearalenone.

We assessed the mycobiota diversity and mycotoxin levels present in wild rice (Oryza latifolia) from the Pantanal region of Brazil; fundamental aspects of which are severely understudied as an edible plant from a natural ecosystem. We found multiple fungal species contaminating the rice samples; the most frequent genera being Fusarium, Nigrospora and Cladosporium (35.9%, 26.1% and 15%, respectively). Within the Fusarium genus, the wild rice samples were mostly contaminated by the Fusarium incarnatum-equiseti species complex (FIESC) (80%) along with Fusarium fujikuroi species complex (20%). Phylogenetic analysis supported multiple FIESC species and gave support to the presence of two putative new groups within the complex (LN1 and LN2). Deoxynivalenol (DON) and zearalenone (ZEN) chemical analysis showed that most of the isolates were DON/ZEN producers and some were defined as high ZEN producers, displaying abundant ZEN levels over DON (over 19 times more). Suggesting that ZEN likely has a key adaptive role for FIESC in wild rice (O. latifolia). Mycotoxin determination in the rice samples revealed high frequency of ZEN, and 85% of rice samples had levels >100 µg/kg; the recommended limit set by regulatory agencies. DON was only detected in 5.2% of the samples. Our data shows that FIESC species are the main source of ZEN contamination in wild rice and the excessive levels of ZEN found in the rice samples raises considerable safety concerns regarding wild rice consumption by humans and animals.