Effect of production and storage of probiotic yogurt on aflatoxin M1 residue

Introduction: Aflatoxin M1 is an important mycotoxin frequently found in milk and dairy products. The main objective of this work was to study the stability of AFM1 during production and refrigerated storage of probiotic yogurt. Materials and methods: Two kinds of probiotic yogurt were made by cow’s milk artificially contaminated with aflatoxin M1 at a level of 100 ng/l, and fermented to reach pH 4.5. The yogurts were stored at 4 °C for up to 21 days. Analysis of aflatoxin M1 in yogurt was carried out, using immunoaffinity column extraction and liquid chromatography coupled with fluorometric detection. Results: The aflatoxin M1 levels in the probiotic yogurts showed a significant decrease (p < 0.05) compared with those initially added to milk. During the refrigerated storage the aflatoxin M1 was lower in‘DELVO-YOG MY 1821’(MY 1821) yogurt than ‘FD-DVS ABY3’ (ABY3), but the difference was not significant (p > 0.05). The percentage loss of the initial amount of aflatoxin M1 in milk was estimated at about 41% and 49% by the end of storage for yogurts made by ABY3 and MY1821 yogurt, respectively. Loss of viability of the probiotic bacteria in presence of aflatoxin M1 was strain dependent. Aflatoxin M1 had no remarkable effect on viability of tested bacteria. Conclusion: The probiotic yogurt can reduce the AFM1 content of initial milk during production and storage. More studies are needed to investigate the effectiveness of other mixed probiotic cultures with different composition, to reduce the AFM1 content of milk.