Evaluation of Listeria monocytogenes populations during the manufacture and vacuum-packaged storage of Kashar cheese
2007
Cetinkaya, F.,University of Uludag, Bursa (Turkey). Dept. of Food Hygiene and Technology | Soyutemiz, G.E.,University of Uludag, Bursa (Turkey). Dept. of Food Hygiene and Technology
The aim of the present study was to investigate the influence of special manufacturing steps and vacuum-packaged storage of Kashar cheese on the behaviour and survival of Listeria monocytogenes inoculated at four different levels varying between 3 to 6 log cfu/mL into the milk. The survival of the pathogen was determined in milk, coagulum, curd and cheese, and at the 1st and 7th days of the storage. The heat treatment process applied after curd acidification step at 75 deg C for 5 min was the most efficient barrier and greatly influenced the viability of the bacteria. Nevertheless, this step was not enough to destroy all the bacteria, especially when inoculated at the level of more than 3 log cfu/mL. For all the groups, this stage resulted in approximately 3 log decrease. Storage at 6+/-1 deg C had no influence on the viability. Results of this study indicate that neither production steps nor storage at 6 deg C for 7 days in vacuum packages was enough to eliminate L. monocytogenes in Kashar cheese, particularly if the initial level was high.
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