Risk factors for mycotoxin contamination of buckwheat grain and its products

The United Nation's Food and Agriculture Organisation have indicated that higher contamination of agricultural produce with mycotoxins is associated with the alterations in the weather conditions. The aim of the current study was to quantify mycotoxin contamination on buckwheat grain at early and complete ripening stages and to estimate the effects of the weather conditions on mycotoxin occurrence as well as to consider natural measures that could potentially reduce mycotoxin contamination in buckwheat products. Mycotoxins deoxynivalenol ( DON), T-2 toxin (T-2), zearalenone (ZEA), aflatoxin B-1 (AFB(1)), ochratoxin A (OTA) were analysed in fully ripe buckwheat grain in 2013 and at early ripening stages in 2014 and 2015. The field trials of buckwheat were set up at the Perloja Experimental Station, Lithuanian Research Centre for Agriculture and Forestry. The least concentrations of the investigated mycotoxins in buckwheat grain were found in 2013. Particularly high concentrations of AFB(1) (up to similar to 72 mu g/kg) were identified in buckwheat grain at early ripening stages in 2014 and 2015. It is likely that buckwheat grain were contaminated with AFB(1) under favourable weather conditions, which were uncharacteristic of Lithuania's climate in 2014 and 2015: hot weather and drought prevailed during the buckwheat flowering and ripening stages. However, such meteorological conditions were less favourable for the synthesis of DON, T-2, ZEA and OTA mycotoxins in buckwheat grain. The high AFB(1) contents found in grain question the quality of buckwheat products. Hulls were 10-fold more contaminated with AFB(1) than grain, which suggests that they serve as a protective shield against buckwheat groat, bran and flour contamination with this mycotoxin. Phenolic compounds were found to decrease the risk of mycotoxin occurrence in grain: with increasing concentrations of rutin, quercetin and total phenolics content in hulls and grain samples, the contents of trichothecene mycotoxins were significantly (P<0.05) lower.