Fate of Aflatoxin M1 During Manufacture and Brining of Feta Cheese

The effect of feta cheese manufacture on aflatoxin M1 (AFM1) content was studied using an enzyme immunoassay technique. Feta cheese was made from milk spiked with 1 and 2 μg AFM1 per kilogram milk. Pasteurization at 63 °C for 30 min caused \u3c10% destruction of AFM1. During cheese making, the remaining AFM1 in milk was partitioned between curd and whey with two-thirds retained in the curd and one-third going into the whey. Cheeses were then stored for 2 mo in 8%, 10%, and 12% brine solutions at 6 and 18 °C. There was a 22% to 27% reduction of AFM1 during the first 10 d of storage, with slightly more loss as salt concentration increased and when the cheese was stored at 18 °C. Further storage caused only slight decrease in AFM1 and after 30 d of brining there was no difference in AFM1 content of the cheese based upon salt concentration of the brine. At 18 °C, no further losses of AFM1 occurred after 30 d, and at 6 °C, there was continued slight decrease in AFM1 levels until 50 d. After 60 d of brining, there was a total loss of 25% and 29% of the AFM1 originally present for cheese brined at 6 and 18 °C, respectively. Thus, the combination of pasteurization, conversion of milk into feta cheese, and at least 50 d storage of cheese in brine caused a total loss of about 50% of the AFM1 originally present in the raw milk