Stability of aflatoxins in processed ras cheese during manufacture and storage

Processed Ras-cheese was made from Ras cheese naturally contaminated with aflatoxin B1, B2, G1 and G2, secreted from toxigenic strains of Aspergillus flavus and Aspergillus parasiticus. The processing of the cheese blend at 90-92 centigrade for 5 minutes reduced its total aflatoxin content by 18.7%, while aflatoxins B1, B2, G1, G2 were reduced by 18.8, 21.3, 16.3 and 20.3% respectively. The storage of processed Ras-Cheese for 60 days at 4 +/- reduced its total aflatoxins by 14.1%, whereas the levels of B1, B2, G1 and G2 were reduced by 13.0, 11.5, 17.2 and 13.8% respectively. The data indicate that the processed Ras-cheese manufactured from contaminated cheese will not be safe for human consumption

Stability of aflatoxin M during processing and storage of yoghurt

Yoghurt was manufactured from three types of standardized cow's milk [3.5% fat, 12.5% solids not fat]; i.e. A, Milk free from aflatoxins [control]; B, Milk artificially contaminated with 10 ug aflatoxin M/kg. The yoghurt was stored for 7 days at 5 +/- 1 centigrade, and the changes in its chemical composition and in its residual aflatoxins were measured. The storage of control or the contaminated yoghurt under these conditions increased its acidity; soluble nitrogen; soluble tyrosine and soluble tryptophane and decreased its pH, dry matter%, fat% and total nitrogen% depending on the length of the storage period. Heating the contaminated milk used for yoghurt manufacture at 85 centigrade for 30 minutes reduced its aflatoxin M content up to 11.2%. Additionally, storing the processed yoghurt at 5 +/- 1 centigrade for a period of 7 days caused a gradual decrease in aflatoxin level that amounted to 23.0, 27.8% and 18.6, 22.0% of aflatoxins M1 and M2 in treatments B and C, respectively. The contamination of milk used for yoghurt manufacture with aflatoxin M affected the activity of starter culture and thereby the production of acidity. It also made the produced yoghurt not safe for human consumption due to the incomplete degradation of the toxin during processing and storage