Behavior of Yersinia-enterocolitica and Aeromonas-hydrophila in Yogurt Made with Probiotic Bacteria - Bifidobacterium Infantis and Lactobacillus-acidophilus

The antagonistic effects of probiotic bacteria on some foodborne pathogens are well known. Inhibition of growth of Yersinia enterocolitica and Aeromonas hydrophila in yogurt made with probiotic bacteria were investigated. Lactobacillus acidophilus and Bifidobacterium infantis were used in different proportions with yogurt bacteria to produce 3 types. All samples were inoculated separately with A. hydrophila and Y. enterocolitica before incubation of yogurts. Yogurt samples were stored at 4+/-1 degrees C for 11 d and at appropriate intervals, pathogenic bacterial counts were performed. pH values of yogurts were also examined.Counts of A, hydrophila and Y. enterocolitica decreased in all yogurt types during the cold storage. While the numbers of viable A. hydrophila and low-level inoculated Y. enterocolitica in yogurts were markedly reduced after 4 d, high-level inoculated Y. enterocolitica survived after 6-8 d of storage.Yogurts containing probiotic bacteria suppressed the A, hydrophila and Y. enterocolitica more effectively than control yogurts.