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Effet d'un chauffage micro-ondes et conventionnel sur la thermorésistance d'une Salmonelle traitée dans un produit à basse activité d'eau. Conséquences sur la qualité du produit

Abstract : We explored in this study the incidence of traditional heating (water bath) and microwave on the thermotolerance of one strain of Salmonella enterica arizonae treated in a low water activity product (aw = 0.51), the sesame cream bought from the Lebanese market. A sodium chloride solution with a higher water activity (aw = 0.99), was also been artificially contaminated by the same strain of bacteria and treated by the two way of treatment. In addition of water bath and microwave treatments, experiments, under the same thermal ramp were realized in the order to compare the kinetic incidence and the way of heating on the thermotolerance of the bacterial strain treated in the sesame cream. We further examined the influence of the microwave treatment on the quality of the sesame cream in order to build an optimization of the treatment. Three criteria have been studied: viscosity, color and the peroxide index. Thereafter, an optimization of this decontamination treatment was highlighted. For both treatments, the water activity seems to have an influence on the thermotolerance of bacteria: the decimal reduction time (D₅₉) of S. enterica, in the sodium chloride solution (aw = 0.99), is two times higher than that obtained in the sesame cream (aw = 0.49, rich in lipids). On the other hand, the Salmonella treated in the cream of sesame (aw = 0.49), rich in lipids, showed a thermotolerance stronger than that treated in the solution of NaCl (aw = 0.99). This protector effect of lipids was known and has previously been reported by many authors who conclude that the protective effect of lipids is attributable to increase the thermotolerance of bacteria. We noted that the thermotolerance of this strain decrease with the pH. The sesame cream has a pH of 5.80 at 20°C where the sodium chloride solution has a pH of 6.50 at 20°C: pH and aw contribute together to increase the thermotolerance of the bacteria in the sesame cream against the NaCl solution. Furthermore, according to our works, it would appear that the same thermal ramp made with two types of heat treatment: water bath or microwave, does not provide equivalent results in terms of destruction of S. enterica. Indeed, for the same temperature reached, microwave treatment systematically gives higher number of decimal reduction than the water bath treatment.
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https://pastel.archives-ouvertes.fr/pastel-00005601
Contributor : Ecole Agroparistech <>
Submitted on : Monday, January 11, 2010 - 8:00:00 AM
Last modification on : Saturday, June 6, 2020 - 5:37:17 PM
Long-term archiving on: : Friday, September 10, 2010 - 2:52:39 PM

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  • HAL Id : pastel-00005601, version 1
  • PRODINRA : 246657

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Lara Hanna-Wakim. Effet d'un chauffage micro-ondes et conventionnel sur la thermorésistance d'une Salmonelle traitée dans un produit à basse activité d'eau. Conséquences sur la qualité du produit. Sciences du Vivant [q-bio]. ENSIA (AgroParisTech), 2008. Français. ⟨NNT : 2008AGPT0047⟩. ⟨pastel-00005601⟩

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