Fate of aflatoxin M1 from milk to typical Italian cheeses: Validation of an HPLC method based on aqueous buffer extraction and immune-affinity clean up with limited use of organic solvents

Abstract

Aflatoxins are mycotoxins produced by several species of Aspergillus fungi which can be found in food and feed. When lactating animals are exposed to feedstuff contaminated by aflatoxin B1, they can excrete its hydroxylated form, aflatoxin M1 (AFM1), into milk. In EU, the AFM1 maximum limit in milk is 0.050 μg kg−1.In this work, we validated a method based on extraction of AFM1 from hard and soft cheese by a sodium citrate solution without the use of organic solvents, and analysis by HPLC-fluorescence detection after purification by immuno-affinity.The method proved to be fit-for-purpose and was successfully verified by participating to proficiency tests.Finally, starting from milk artificially contaminated with AFM1 we prepared four different types of Italian cheese to evaluate AFM1 transfer from milk to cheese and calculate concentration factors occurring during cheese-making processes. We observed an increase of AFM1 concentration in hard cheeses compared to soft cheeses.