Incidence of toxigenic fungi and zearalenone in rice grains from Brazil

Rice (Oryza sativa L.) is one of the most important food crops worldwide. In Brazil, the southern region is the area with the highest production of rice in the country and also has a high average daily intake of rice by the population. The mycoflora, mainly toxigenic Aspergillus and Fusarium species, the presence of AFB1, DON and ZEA in rice grains, as well as daily intake estimates for the Southern Brazilian population were evaluated. The rice grain samples were collected during the 2017 crop from different harvest periods. According to the mycological tests, the samples presented a high count of fungal colonies in the pre and post-harvest, where the incidence of the F. graminearum species complex (52%) was significantly predominant. This group can be responsible for ZEA production, as found in this study in parboiled rice, mainly because most of the isolated strains were producers of high ZEA levels in the pre-harvest (77%) and post-harvest after natural (79%) and artificial (75%) drying of the rice. Only ZEA showed significant results in the rice grain analyzed (60%) at levels of 90.56 to 126.31 μg/kg, where 36% of the samples were significantly higher than the current maximum limit stipulated in Brazilian regulations and by the European Commission. Despite this, the dietary exposure of ZEA estimated for the southern Brazilian population was below the provisional maximum tolerable daily intake level of 0.5 μg/kg body weight/day set at international regulations.