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RESEARCH PRODUCT

Study on mycotoxin contamination of maize kernels in Spain

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Abstract Mycotoxins are secondary metabolites produced mainly by fungal species belonging to the genera Fusarium, Aspergillus and Penicillium and belong to the most relevant contaminants of food and feed. Cereals are the main source of mycotoxins in the diet. The most prominent mycotoxins are aflatoxins B1, B2, G1 and G2 (AFB1, AFB2, AFG1 and AFG2), fumonisins B1 and B2 (FB1 and FB2), ochratoxin A (OTA), zearalenone (ZEA), deoxynivalenol (DON), 3- and 15-acetyl-deoxynivalenol (3- and 15-ADON), and T-2 and HT-2 toxins. Maximum levels allowed in food are very different depending on mycotoxin and food type, consumer susceptibility and current legislation in each country. Among cereals, maize and its derivatives deserve special attention. The present study was designed to investigate the occurrence of these mycotoxins in Spanish maize kernels collected in different regions for a five-year period (2015–2019) using a multi-mycotoxin UPLC-MS/MS method. Ninety-eight samples of maize kernels collected in 26 Spanish grain stores were ground to fine powder, extracted with acetonitrile-water-formic acid (80:19:1, v/v/v), centrifuged and analyzed by UPLC-ESI-MS/MS using matrix-matched calibration. The method was validated and mean recovery rates were 83–103.4% and mean relative standard deviations ranged from 4.1 to 8.5%. FB1, FB2, DON, 3-ADON, ZEA, AFB1, AFB2, AFG2, T-2 and HT-2 toxins were detected at levels higher than their respective limits of quantification in 71.4%, 56.2%, 31.6%, 5.02%, 24.5%, 9.2%, 9.2%, 2%, 5.1% and 5.1% of maize kernel samples, respectively. OTA was not detected. Among the positive samples, 20.4%, 5.1%, 3%, and 3% had levels exceeding the European Union permissible limits for FB1+FB2, ZEA, AFB1, and total aflatoxins, respectively. Co-occurrence of various mycotoxins (two to seven) in the same sample at quantifiable levels was observed in 33.5% of samples being the association of FB1, FB2 and DON the most frequent, followed by the presence of FB1, FB2, ZEA and DON.