Survival of Listeria monocytogenes during the manufacture, ripening and storage of Turkish white cheese made from cow's and sheep's milk

Authors: MUHAMMET ARICI, MEHMET DEMİRCİ, H. HÜSNÜ GÜNDÜZ

Abstract: In this research survival Listeria monocytogenes has been investigated during manufacturing, ripening and storage of the turkish white cheese made from cow's milk and sheep's milk. Pasteurized cow's and sheep's milk were inoculated with 10^3 L. monocytogenes /ml and than processed into cheese. Cheese samples were stored in PET jars after pre-ripening during 20 weeks at 4°C and analysis were carried out at certain period. In all samples after 5 days in room temperature L. monocytogenes count has reached to 10^5/g and pH decreased to 5.0. L. monocytogenes count in the cold stored cheese samples was determined as >10^4/g after 8 weeks; >10/g in cheese samples made of cow's milk and >100/g in cheese samples made of sheep' milk after 20 week of storage. pH values in the cheese samples of cow's milk and sheep's milk were found as 4.18 and 3.95 respectively after 20 week of storage. Water activity (a_w) in all samples was calculated as 0.97 after 1 week and 0.966 after 20 week of storage.

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