Note:: Behaviour of Escherichia coli O157:H7, Listeria monocytogenes 4b and Yersinia enterocolitica O3 in pasteurised and non-pasteurised kefir fermented for one or two days

The behaviour of three selected food-borne pathogens, E. coli O157:H7, L. monocytogenes 4b and Y. enterocolitica O3, added to fermented and pasteurised kefir was monitored. Populations of the three strains increased in one-day-fermented kefir, but only E. coli O157:H7 increased in two-days-fermented kefir during fermentation. None of the strains grew during cold storage (4 +/- 1degreesC), although E. coli O157:H 7 and L. monocytogenes 4b survived up to 21 days in all samples cold. Y. enterocolitica 03 was the most susceptible strain that was present in one-day-fermented kefir for at least 14 days. Two-days-fermented kefir samples were more acidic than those of one-day-fermented samples, but none of the samples was safe enough to create an environment to eliminate the pathogens.