بررسي جداسازي و شناسايي گونه هاي Listeria monocytogenes ازكارخانه هاي توليد كننده فرآورده هاي گوشتي و لبني شهرستانهاي تنكابن ونوشهر و بررسي الگوي مقاومت حرارتي آنها

Survey of contamination rate of Listeria monocytogenes in dairy and meet products from Tonekabon and Noshahr factories and evaluation of its heat resistance pattern

In this research, products of Tonekabon and Noshahr dairy and meet factories were sampled and looked for Listeria monocytogenes. Dairy products were low and double fat milk, low and double fat yogurt, cream, cheese and butter. Meet products were hamburger and sausage. Sample size was 50 for each product. Finally, by the standard method for Listeria isolation, L.monocytogenes was isolated from a double fat milk sample from a dairy factory in Tonekabon city. Then the heat resistance of the isolated strain was measured under different heat conditions and its property was compared with standard strain. Comparison of data was evaluated with ANOVA table (SPSS program). Given data were log10 numbers of bacteria colonies after heat condition on PALCAM agar based on the suggested method by Brocklehurst and Parker. Comparison of standard strain and isolated strain data shown significant difference between their heat resistances properties. The results showed that the isolated L. monocytogenes is heat resistance.