The fate of aflatoxin M1 in milk used in the production of Libyan yoghurt under simulated conditions

This study was carried out to determine if there was a relationship between the reduction of Aflatoxin M1 (AFM1) and the method used for production of yoghurt at dairy factories in the north west of Libya. Three milk samples were separately spiked with AFM1 to obtain AFM1 concentration of 0.85, 2.78 and 4.59ng AFM1/ml in the milk samples. Natural yoghurt containing viable bacteria (Lactobacillus acidophilus and Streptococcus thermophiles) was added to each spiked milk sample as starter culture. During the yoghurt production process growth of viable bacteria was observed. The levels of AFM1 in yoghurt samples were quantified using HPLC after the extracts had been purified using an immunoaffinity column procedure. During the production of yoghurt, the levels of AFM1 decrease by 57.6, 47.9 and 51.2%. Bacteria used in the production of yoghurt did not affect AFM1 levels in milk, although bacteria cell count increased from 5.37 to 8.94 log10 cfu/ml accompanied by pH decrease from 6.3 to 4.6.