INFLUENCE OF STORAGE TEMPERATURE ON VIABILITY OF LISTERIA MONOCYTOGENS AND SALMONELLA TYPHIMURIUM IN WHITE SOFT CHEESE

The present experiment was carried out to study the effect of storage temperatures of white soft cheese on the survival and growth of Listeria monocytogenes and Salmonella typhimurium, L. monocytogenes showed slight decrease in viable cell count during the first few days of refrigerator storage (8.0 log CFU/g) followed by stationary period (4 weeks). The detectable cells increased gradually, near the end of the experiment which lasted for about 4 months, then the viable cell count decreased gradually again. Whereas at room temperature the organism exhibited slight decrease in number (0.4 log CFU/g) followed by short stationary period, then the viable cell count increases gradually but slowly till the end of the. experiment (20 days) at which the product Showed signs of spoilage. S. typhimurium appeared to be a microorganism of normal behavior. It showed decrease in number directly after storage by 0.3 and 0.9 Log CFU/g, followed by stationary phase for about 28 and 12 days, finally the organism tend to decrease gradually until the end of the experiment (65 and 36 days) for samples stored at 4°C and room temperature respectively due to the spoilage of thecheese. Public health importance and suggestcd control measures of the examined organisms were discussed to improve the keeping quality of the while soft cheese.