摘要
The public health significance of Yersinia spp. gives a new dimension to the prevailing food chain, wherein the foods do get exposed to heat and cold treatments. In this study, the effect of heat treatment on the native isolates of Yersinia enterocolitica CFR 2301 and Y. intermedia CFR 2303 revealed the D-values ranging from the lowest of 0.08 min at 65℃ in skim milk/beef gravy to the highest of 18.52 min at 50℃ in beef gravy. The heat sensitivity of both these cultures was in the order of Milli-Q water > 0.85% saline > skim milk > beef gravy. The z-values of the test cultures ranged from 7.55℃ for Y. intermedia to 12.08℃ for Y. enterocolitica. The heat sensitivity in Y. enterocolitica appeared to be related with growth incubation temperatures and also fatty acid profile of cell membrane. The effect of low temperature treatments (–20 ℃, 0℃ and 4℃ for 20 d) in water, saline and skim milk revealed the ability of Y. enterocolitica to survive more efficiently at –20℃, while Y. intermedia was more tolerant at 0℃. In packaged drinking water, Y. enterocolitica could survive and grow at 4℃ and 16℃, while at 30℃, inactivation was rapid. The findings did indicate that heat and cold treatments would not always ensure safety from Y. enterocolitica and Y. intermedia in the food chain.
The public health significance of Yersinia spp. gives a new dimension to the prevailing food chain, wherein the foods do get exposed to heat and cold treatments. In this study, the effect of heat treatment on the native isolates of Yersinia enterocolitica CFR 2301 and Y. intermedia CFR 2303 revealed the D-values ranging from the lowest of 0.08 min at 65℃ in skim milk/beef gravy to the highest of 18.52 min at 50℃ in beef gravy. The heat sensitivity of both these cultures was in the order of Milli-Q water > 0.85% saline > skim milk > beef gravy. The z-values of the test cultures ranged from 7.55℃ for Y. intermedia to 12.08℃ for Y. enterocolitica. The heat sensitivity in Y. enterocolitica appeared to be related with growth incubation temperatures and also fatty acid profile of cell membrane. The effect of low temperature treatments (–20 ℃, 0℃ and 4℃ for 20 d) in water, saline and skim milk revealed the ability of Y. enterocolitica to survive more efficiently at –20℃, while Y. intermedia was more tolerant at 0℃. In packaged drinking water, Y. enterocolitica could survive and grow at 4℃ and 16℃, while at 30℃, inactivation was rapid. The findings did indicate that heat and cold treatments would not always ensure safety from Y. enterocolitica and Y. intermedia in the food chain.
