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pp.175-180
Escherichia coli O157:H7 and Salmonella ser. typhimurium are pathogens involved in food poisoning in numerous countries. This study aimed to obtain knowleges on the survival of E. coli O157:H7 KSC 109 and S. ser. typhimurium ATCC 14028 in fermented milk products which were on sale in Suwon Yakult supplier. To the final concentration of 10³-10⁴ cfu/ml of E. coli O157:H7 KSC 109 or S. ser. typhimurium ATCC 14028 in the fermented milks, Metchnikoff, Ace, Yakult, Mastoni and Super100 were inoculated with these pathogens and then were stored at 4 and viable cells of these pathogens were periodically counted. The results showed that the survival of two pathogens differed in the different types of fermented milks tested. Number of surviving E. coli O157:H7 KSC 109 and S. ser. typimurium ATCC 14028 cells (initial inoculum, 10³-10⁴ cfu/ml) were decreased to 10', 102 cfu/ml in Ace after 100 hours, and were decreased gradually to 10¹ cfu/ml in Yakult after 250 hours. In the other fermented milks, viable cells of E. coli O157:H7 KSC 109 was not drastically decreased but those of S. ser. typhimurium ATCC 14028 was decreased gradually to 10² (Mastoni), and to 10¹ cfir/ml (Super100) after 250 hours. It appeared that S. ser. typhimurium ATCC 14028 was more susceptible than E. coli O157: H7 KSC 109 at low pH. Vibale cells of E. coli O157:H7 KSC 109 was not drastically decreased in most of fermented milks tested except Ace and Yakult, but in general, S. ser. typhimurxum ATCC 14028 was drastically decreased in most of the fermented milks. The major inhibition factor against these pathogens in the fermented milks during storage at 4℃ appeared to be the acidity and the metabolites produced by the starters bacteria used in fermented milk products.
