Fate of aflatoxin M1 in cheese whey processing

Abstract

AflatoxinM1 (AFM1) is an important mycotoxin frequently found in milk and in dairy products. It is aminor metabolic product of Aspergillus flavus and A parasiticus. However, it occurs in dairy products as a metabolite formed in cows from aflatoxin B1 contained in animal feeds. In cheese production, AFM1 distributes between curd and whey, being present in products derived from cheese whey processing. In this study, cheese whey from dairy processing was artificially contaminated with the mycotoxin at about 0.1 μg lֿ¹. Ultra-filtration experiments of whey were carried out in order to determinate AFM1 distribution between retentate (protein-rich fraction) and permeate (lactose-rich fraction). Recoveries of AFM1 in retentate were 72.6–86.4% while, in permeate, recoveries were in the range 2.4–14.7%. Partition coefficients of AFM1, lactose and protein were calculated to determine whether there was an interaction between AFM1 and protein. In all experiments, AFM1 partition coefficient was lower than 1, whilst for lactose coefficients close to 1 were determined, showing an affinity of aflatoxin M1 to the protein-rich fraction (retentate).