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Caractérisation de l'influence de facteurs environnementaux sur l'écologie microbienne du jambon cuit tranché.

Abstract : Reducing salt and nitrite used to limit cooked ham spoilage is a public health concern, but it can lead to changes in microbial ecosystems and enhance ham spoilage. Our objective was to characterize (i) the microbial communities of hams from a production plant, (ii) the production of spoilage metabolites and to predict how those factors would change in the context of a reduction in the salt and the nitrite content. Among the process parameters studied, the slicing line was an important factor. Two profiles of communities were observed at the use-by date according to the slicing line. They were composed of nine species representing 95% of abundance. The presence of those species was correlated with different productions of pyruvate-derived fermentation metabolites.Based on the species identified, we designed a synthetic bacterial community that we inoculated on a synthetic ham-like agar medium with different salt and nitrite concentrations. This synthetic ecology approach showed that a reduction under 12 g/kg of salt and 25-30 mg/kg of nitrite correlated with a stronger species disequilibrium, associated with an exponential Leuconostoc growth and a decreased Carnobacterium growth. This disequilibrium was correlated to a 30% increase of ethanol and D-lactic acid production, which suggests a higher spoilage risk for hams at those concentrations. We then tested those concentrations in industrial condition of production. Microbial behavior was very different according to the profiles of community of hams sliced on the different lines. For the first profile, the behavior of the community was similar to the one observed in the synthetic ecosystem: we observed a disequilibrium of species abundance under 12 g/kg of salt and 25-30 mg/kg of nitrite and a decrease in Carnobacterium divergens abundance. For the second profile, dominated by Serratia proteamaculans, community structure was only slightly affected by a reduction of salt and nitrite. Finally, we observed that reducing the salt and the nitrite content increased yeasts growth.This work highlights the importance of process in the structuration of microbial communities in the final product. This factor is to take into account to understand the impact of any other environmental change on microbial behavior.
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  • HAL Id : tel-03270836, version 1

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Marine Zagdoun. Caractérisation de l'influence de facteurs environnementaux sur l'écologie microbienne du jambon cuit tranché.. Biologie moléculaire. Université Paris-Saclay, 2020. Français. ⟨NNT : 2020UPASA003⟩. ⟨tel-03270836⟩

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