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

The aim of this study was to compare between the efficiency of thermal (Pasteurization) and non-thermal (Ozonation and gamma irradiation) treatments for their antimicrobial effects on three important foodborne pathogens: L. monocytogenes, S. aureus and E. coli in milk. Additionally, the effect of these treatments on sensory characteristics of milk samples was also monitored before and after treatments. Milk samples were collected and inoculated with the reference strains of L. monocytogenes "ATCC7644", E. coli "ATCC25922" and S. aureus "ATCC6538" where the count reached an approximately 107Log10 cfu/ml milk (Control sample). Pasteurization at 63{u00B0}C for 30 minutes, treatment with ozone at 1.5, 2 and 2.5mg/l for 5 minutes and finally milk samples were subjected to gamma irradiation at 2, 3, 4 and 5 kGy. A three trial based experiment was designed for each treatment and statistical analysis was performed. The results showed that the treatment using pasteurization was the most significant result as it could be eliminated all inoculated pathogens under study. Otherwise, the organisms could not be detected any more after application of pasteurization. All the samples are positive for inoculated pathogens post to the ozonation and gamma irradiation treatments. Gamma irradiation had no adverse effect on sensory characteristics of milk, while ozonation and pasteurization induce adverse effects on sensory characteristics of milk

Issued also as CD