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Poster De Conférence Année : 2013

Specific industrial bacteria adhering on stainless steel equipments are able to further contaminate and spoil liquid egg products

Marie-Clarisse Techer
  • Fonction : Auteur
Sophie Jan
Florence Baron
  • Fonction : Auteur
  • PersonId : 1202779

Résumé

Introduction: Egg products resulting from the breaking of shell eggs, giving rise to egg yolk and egg white, or whole egg, are used in highly diversified sectors for their functionalities (coloring, thickening, emulsifying and gelling properties), such as in dairy, meat and seafood products. Liquid egg products are generally pasteurized at moderate temperatures because of the heat sensitivity of the proteins and stored at refrigeration temperatures. Contamination by Salmonella, which remains the major safety preoccupation of this sector, is now under the control of breeding surveillance and of effective pasteurization processes. However, the manufacturers now encounter new types of microorganisms selected by the preservation processes themselves. The spoilage flora resisting to pasteurization may adhere on the surfaces of the pipelines or inside the stainless steel equipment. This flora may lead to the contamination of the egg product passing through the pipelines, hence causing a massive and fast contamination of the final egg product. The spoilage flora can lead to technological and/or organoleptic problems (coagulation, changes in colour or in flavour) due to the production of hydrolytic enzymes, even at low temperature. The aim of this study was to investigate the whole egg spoilage potential of isolates collected from stainless steel equipment in the egg processing industry.[br/] Material and methods: Sterile stainless steel chips were suspended inside the pipelines of 7 egg processing companies, at two process levels, before and after the pasteurizer, and at two seasons (summer and winter). After two months, the adhering flora was harvested by sonication and scrapping in tryptone salt, followed by plating onto BHI-YE agar and incubation for 1 to 7 day(s) at 30°C, with or without oxygen. After incubation, the colonies were identified by 16S rDNA sequencing. Isolates were selected for further in vitro investigation on their ability to adhere on stainless steel surfaces. After bacterial adhesion, sterile liquid whole egg was added on the chips and incubated at various temperatures. Enumeration and visual observations were carried out in order to detect contamination and spoilage, i.e. transformation of whole egg into a white slurry cream. Results: A broad range of diversity was highlighted even if a majority of facultative aero-anaerobic Gram positive bacteria was found, such as Streptococcus, Micrococcus, Staphylococcus, Microbacterium, Lysinibacillus and Bacillus. The adhesion capacity of the harvested isolates did not depend on their location in the process (before or after pasteurization), neither on the season (cold or warm) nor on the company. The level of adhesion depended more on the species than on the genus. While the whole collection was able to grow in liquid whole egg, only the genera Lysinibacillus and Bacillus were able to provoke a detectable spoilage. Significance: The adhesion of microorganisms on industrial surfaces is frequently observed in the food industry. Poorly controlled, adhering bacteria can be the source of food product contamination and/or food spoilage, and therefore can lead to high economic losses for the industry.
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Dates et versions

hal-01135774 , version 1 (25-03-2015)

Identifiants

  • HAL Id : hal-01135774 , version 1
  • PRODINRA : 286953

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Marie-Clarisse Techer, Sophie Jan, Florence Baron. Specific industrial bacteria adhering on stainless steel equipments are able to further contaminate and spoil liquid egg products. Microbial Spoilers in Food, Jul 2013, Quimper, France. , 2013. ⟨hal-01135774⟩
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