Thesis (Ph.D.) - Cairo University - Faculty of Veterinary Medicine - Department of Food Hygiene and Control

Two hundred & eighty samples [100 samples of raw milk, 50 samples of ice cream, 30 samples of plain yogurt and 100 samples of cheese (25 each of soft, hard, processed and Kariesh)] were randomly collected from dairy farms, dairy shops and groceries in Cairo and Giza governorates. Coliforms could be detected in 96%, 58%, 50%, 80%, 84%, 72 % and 60% of raw milk, ice cream, plain yogurt, Kariesh cheese, soft cheese, hard cheese and processed cheese samples, respectively. Escherichia coli and other species of coliforms could be detected in the examined samples at varying percentages. The incidence of Enterohemorrhagic E. coli by using MUG test were 22.60%, 30%, 25%, 25%, 66.67%, 57.14% and 42.86% of the examined samples of raw milk, ice cream, plain yogurt, kariesh cheese, soft cheese, hard cheese and processed cheese, respectively, also shigatoxigenic E.coli could be serologically identified which belonged to O157, O78, O103, O118, O124, O145 and O164, it was evident that shiga toxins could be detected using ELISA test in raw milk, ice cream, Kariesh cheese and processed cheese samples. By using PCR technique, shiga toxin (Stx2) gene was confirmed in the examined raw milk samples. Shigatoxigenic and non toxigenic E. coli strains survived for shorter period in acidophilus yogurt than in traditional yogurt when stored at 4 {u00B0}C, also its behavior in raw, pasteurized and boiled milk stored at different storage temperatures (4, 8 and 12 {u00B0}C) was studied. The public health significance of isolated strains from the examined samples of milk and some dairy products are discussed as well as the suggestive hygienic measures for improving the quality of milk and its products.

Issued also as CD