The survival of listeria monocytogenes in yoghurt and ice cream

The ability of L. monocytogenesas an opportunistic pathogen of humans and animals, to survive and grow under various adverse environmental conditions, makes it a potential health hazard afterthe consumption of contaminated dairy products, it often implicated in several outbreaks of listeriosis. This study was conducted to investigate the survival of L. monocytogenes strain (NCTC13372) when inoculated with a population level of 6.95 log cfu/g and 7.64 logcfu/g and stored at 4ºC for 15 days and 3 months at -18ºC for yoghurt and ice cream respectively. The obtained results indicated that complete inactivation of the tested organism wasn’t achieved till the end of storage periods and the inoculated L. monocytogenes was survived in both yoghurt and ice cream throughout the trial. It is concluded that in the dairy industry, we cannot rely upon either fermentation process and storage at refrigerating temperature or upon storage at freezing temperature during yoghurt and ice cream manufacturing to control L.monocytogenes pathogen in order to provide safe products for consumption.