Two year survey on the occurrence and seasonal variation of aflatoxin M1 in milk and milk products in Serbia

•Two year survey of AFM1 in milk and milk products with 1438 samples.•Milk powders had the highest mean AFM1 concentration of all types of milk products.•AFM1 concentration higher in winter and spring compared to summer and autumn.•AFM1 concentration dropped down in 2014 compared to 2013.

The incidence of contamination of aflatoxin M1 (AFM1) in milk and milk products samples collected in Serbia was investigated by using the competitive enzyme linked immunosorbent assay (ELISA) technique. A total of 1438 samples composed of 678 raw milk, 438 heat treated milk and 322 milk product samples that were analyzed during the period of 2013–2014, including all seasons. The AFM1 levels exceeded the European Union maximum residue permitted amount (EU MRL) in 56.3% raw milk, 32.6% heat treated milk and 37.8% of milk product samples. Milk powders had the highest mean AFM1 concentration (0.847 μg/kg) of all types of milk products examined. Mean concentration of AFM1 in raw milk samples during the period of winter in Serbia was 0.358 μg/kg and did not significantly differ from the mean concentrations of 0.375 μg/kg during the spring. However, the AFM1 raw milk concentration in the summer (0.039 μg/kg) and autumn season (0.103 μg/kg) was significantly lower. Seasonal variation of AFM1 concentrations in heat treated milk samples followed the trend observed in raw milk. Mean raw milk AFM1 concentration has dropped down by 10 fold from 0.314 μg/kg in 2013 to 0.035 μg/kg in 2014. The fraction of raw milk samples exceeding the EU MRL has decreased from 62.3% to 11.5% by the end of 2014.