A model study of Escherichia coli O157:H7 survival in fermented dry sausages – Influence of inoculum preparation, inoculum procedure, and selected process parameters

Authors: Naim, Fadia; Messier, Serge; Saucier, Linda; Piette, Gabriel
Abstract: The in uence of inoculum preparation, inoculation level, and inoculation procedure on Escherichia coli O157:H7 inactivation during the manufacture of fermented sausage was evaluated in a model study. Prior growth in glucose-enrichedtryptone soya broth, which provided exposure to mildly acidic conditions (pH 4.8), had no effect on the later survival of E. coli O157: H7 strains 5-1 and ATCC 43894 under extremely acidic conditions (pH 2), but the same strains became sensitive to acidity after 7 days of incubation on the surface of refrigerated beef (as per the normal contamination route from slaughter to further processing). In subsequent sausage production trials, the extent of destruction observed for E. coli O157:H7 strains F-90, 5- 1, and ATCC 43894 inoculated directly into the meat batter was unchanged when the inoculation level was decreased from 7.3 to 4.7 log CFU/g, but the level of inactivation was ca. 1 log higher when the surfaces of beef cuts, rather than the batter, were inoculated 7 days prior to processing. Regardless of processing conditions (fermentation to a pH of #5.0 at 24 or 378C, drying at 148C to a water activity [aw] value of 0.91 or 0.79), strains F-90, 5-1, and ATCC 43894 showed similar survival capacities during the manufacture of sausage. A ;2-log reduction in pathogen numbers was generally obtained after samples were dried to an aw of 0.91, irrespective of fermentation temperature. The addition of a 5-day predrying holding stage at the fermentation temperature signi cantly (P , 0.05) increased pathogen inactivation when fermentation was carried out at 378C (but not when it was carried out at 248C). However, signi cant pathogen reductions (4 to 5 log CFU/g) were achieved only for extensively dried products (aw 5 0.79)
Document Type: Article de recherche
Issue Date: 1 December 2003
Open Access Date: Restricted access
Document version: VoR
Permalink: http://hdl.handle.net/20.500.11794/34956
This document was published in: Journal of food protection, Vol. 66 (12), 2267-2275
Alternative version: 10.4315/0362-028X-66.12.2267
Collection:Articles publiés dans des revues avec comité de lecture

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