Survival of virulent Yersinia enterocolitica during the manufacture and storage of Turkish Feta cheese.

The ability of virulent Y. enterocolitica (serotype 0:3) to grow and survive during the manufacture and storage of Turkish Feta cheese was studied. Pasteurized whole cow's milk inoculated with different amounts of Y. enterocolitica was used to make cheese. Y. enterocolitica was examined during the manufacture and ripening period of Feta cheeses with particular reference to (a) different inoculation levels of Y. enterocolitica, (b) the addition of starter culture, (c) salt concentration and (d) storage time. Cheeses were also examined periodically for total solids, moisture and salt contents, pH values, and aerobic plate count. Selected Y. enterocolitica colonies were confirmed biochemically. An increase in the number of Y. enterocolitica was observed during manufacture. Following salting and throughout the storage period, the numbers of Y. enterocolitica decreased at a rate which depended on salt concentration, starter activity, and storage time.