Effect of Ras cheese manufacturing on the stability of DDT and its metabolites

Residue levels of DDT were analyzed in 25 samples of liquid milk as well as 25 samples of Ras cheese collected from different regions in Great Cairo Governorates. Levels of DDT and its metabolites in liquid milk samples were higher than those in Ras cheese. The detected levels of pesticides in milk and cheese were lower than the maximum acceptable limits (MAL(s)) recommended by FAO/WHO (1993). The reduction levels of total DDT in Ras cheese made from contaminated milk with different levels of DDT (0.1, 1.0 and 10.0 mg/kg fat) were 40.6, 33.9 and 25.5%, respectively, at the end of storage period. The isolated Ras cheese microorganisms reduced the total DDT residues by 10.8, 11.8 and 4.8% for Streptococci, lactobacilli and yeasts, respectively, at the end of incubation period. (C) 1997 Published by Elsevier Science Ltd. All rights reserved.