Prevalence of aflatoxin M1 in raw milk and three types of liquid milk products in central-south China

The objective of this study was to survey the prevalence of aflatoxin M1 (AFM1) in raw, pasteurized, extended shelf life (ESL) and UHT milk from central-south China. A total of 734 milk samples, comprising raw milk (133 samples), pasteurized milk (410), ESL milk (93) and UHT milk (98), were obtained between Nov. 01, 2018 and Mar. 31, 2019. The AFM1 concentrations in milk samples were detected by ELISA and confirmed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Five hundred and ninety samples (80.4%) were positive for AFM1; the mean value was 23.7 ng/L, and the range was 5.1-104.4 ng/L. The percentages of AFM1 positive raw, pasteurized, ESL and UHT milk samples were 75.2, 82.2, 81.7 and 78.6%, respectively. The AFM1 concentration in raw milk was significantly lower (p < 0.05) than that in pasteurized and ESL milk, and the AFM1 level in UHT milk tended to be lower (p < 0.10) than that in pasteurized and ESL milk. The AFM1 levels exceeded the EU legal limit of 50 ng/L in 0, 11.5, 18.3 and 3.1% of raw, pasteurized, ESL and UHT milk samples, respectively. All milk samples tested had levels far below China's legal limit of 500 ng/L. Therefore, the AFM1 content in raw milk and milk products in central-south China does not pose a public health threat, but dose attention should nonetheless be paid to milk AFM1, given the high positive rate of 80.4%.