Growth of pathogenic Yersinia enterocolitica strains in minced meat with and without protective gas with consideration of the competitive background flora.
The growth of two pathogenic Yersinia enterocolitica strains (O:3, O:9 at 1 degree C, 4 degrees C, 10 degrees C and 15 degrees C) in minced meat produced under sterile conditions and in minced meat with a normal background flora was investigated. In addition, the influence of treatment with a protective gas (20% CO2, 80% O2) was tested. In minced meat produced under sterile conditions and incubated under normal atmospheric conditions, Y. enterocolitica increased in numbers by only 1 log at 1 degree C and 3.5 logs at 4 degrees C within 14 days. At 10 and 15 degrees C, there was about a 5-log increase in cell numbers within 5 days. There was a marked inhibition of growth by the background flora on Y. enterocolitica. This effect was so marked that only a slight additional inhibition on the growth of Y. enterocolitica at 1, 4 and 10 degrees C was observed under the CO2:O2 modified atmosphere. This is in contrast to the situation where minced meat with a low total bacterial count was used, and the growth of Y. enterocolitica was adversely affected by the CO2:O2 environment. The significance of raw minced meat in the development of human Y. enterocolitica infections is also discussed.
Kleinlein
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N
Institut für tierärztliche Lebensmittelhygiene, Universität Zürich, Switzerland.
Untermann
F
F
D000818:Animals; D001419:Bacteria / Q000254:growth & development; D002245:Carbon Dioxide / Q000494:pharmacology*; D002417:Cattle; D015169:Colony Count, Microbial; D005516:Food Microbiology; D008460:Meat; D010100:Oxygen / Q000494:pharmacology*; D013696:Temperature; D015008:Yersinia enterocolitica / Q000187:drug effects / Q000254:growth & development*
D002245:Carbon Dioxide; D010100:Oxygen