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- Title
INACTIVATION OF VEROCYTOTOXIGENIC ESCHERICHIA COLI AND LISTERIA MONOCYTOGENES CO-CULTURED WITH LACTOBACILLUS SAKEI IN A SIMULATED MEAT FERMENTATION MEDIUM.
- Authors
PAPATHOMOPOULOU, K.; KOTZEKIDOU, P.
- Abstract
The effect of bacteriocin producing Lactobacillus sakei 4413 (an isolate from a Greek dry-fermented sausage) on inhibition of co-cultured verocytotoxigenic Escherichia coli or Listeria monocytogenes strains was investigated. In the simulated meat fermentation medium (containing a mixture of nitrogen sources, glucose, sodium chloride and curing agents, with initial pH 6.5) incubated at 25C, L. sakei 4413 produced the highest concentration of bacteriocin in the exponential growth phase, reducing the pH of the medium to 4.3 and producing 0.54% w/v lactic acid. Three primary models (i.e., the Gompertz model, the Baranyi model and the Whiting-Buchanan model) were evaluated for modeling survival curves of different verocytotoxigenic E. coli and L. monocytogenes strains co-cultured with L. sakei 4413. The inactivation models evaluated indicated an acceptable degree of goodness-of-fit. However, the Whiting-Buchanan model seems more accurate for fitting microbial inactivation curves, showing the highest R2 values and lowest root mean square values in co-cultures of L. sakei and E. coli or L. monocytogenes. Using the Whiting-Buchanan model, a 4-D (99.99%) inactivation of E. coli and L. monocytogenes strains was achieved after 50.9 and 48.7 h, respectively, in co-cultures with L. sakei 4413 in the simulated meat fermentation medium incubated at 25C. In a synthetic medium containing a mixture of different nitrogen sources (i.e., peptone from meat, meat extract, yeast extract) the effect of temperature and glucose on the inhibitory action of L. sakei 4413 against E. coli O157 EDL-932 was studied by central composite response surface methodology. The results indicate that the minimum time for a 4-log decline (11.5 h) for E. coli O157 EDL-932 in co-culture with L. sakei 4413 can be achieved at 26C and 2% w/v glucose. The results indicate that L. sakei 4413 could be used as bio-preservative or starter adjunct in meat fermentations in order to minimize the risk associated with the survival of the above foodborne pathogens. PRACTICAL APPLICATIONS The development of indigenous starters is very promising in order to produce fermented sausages with high sanitary and sensory qualities. This work contributes to the development of a starter adjunct from an indigenous L. sakei (isolated from a traditional sausage manufactured by a Greek producer). L. sakei added in a model system inactivates verocytotoxigenic E. coli and L. monocytogenes. As L. sakei strain is well adapted to the meat environment, it will lead to sausages that do not present a sanitary risk.
- Subjects
ESCHERICHIA coli; LISTERIA monocytogenes; VEROCYTOTOXINS; LACTOBACILLUS; FERMENTATION; MEAT
- Publication
Journal of Food Safety, 2009, Vol 29, Issue 3, p331
- ISSN
0149-6085
- Publication type
Article
- DOI
10.1111/j.1745-4565.2009.00160.x