مطالعه تاثيردوز تلقيح يرسينيا انتروكوليتيكا بر بقاء آن در پنير سفيد نگه داري شده در آب نمك

The effect of inoculation levels of Yersinia enterocolitica on its survival in brined white cheese

The effect of inoculation levels on survival of Yersinia enterocolitica during the manufacture and storage of white cheese in brine was studied. Because of the capability of Y. enterocolitica to grow and survive at 0-4 °C, low pH values and presence of salt, it is probable for it to survive during the manufacture, ripening and storage of brined white cheese at refrigerator temperature. Lyophilized Y. enterocolitica (serotype O: 3) was activated by two consecutive cultures in BH1 broth. In order to determine the initial inoculumsʹ level of Y. enterocolitica, the turbidity of culture tubes were measured. Pasteurized cowʹs milk inoculated with different inoculumsʹ levels (102, 103 and 104 cfu/ml of cheese milk) of Y. enterocolitica was used for cheese making. Y. enterocolitica was enumerated during the manufacture, ripening and storage period. Selected Y enterocolitica colonies were confirmed biochemically. Cheese samples were also examined periodically for total solids, moisture, salt contents and pH values. The results indicated an increase in the number of Y. enterocolitica during cheese manufacture. However, following salting and during the ripening and storage period, the number of Y. enterocolitica decreased significantly (p<0.05). The inoculums level had significant (p