title: Role of incubation conditions and protein fraction on the antimicrobial activity of egg white against Salmonella Enteritidis and Escherichia coli.
abstract: The mechanism of egg white antimicrobial activity involves specific molecules and environmental factors. However, it is difficult to compare the data from the literature because of the use of various bacterial strains and incubation conditions. The aim of our study was to determine the effect of temperature, pH, inoculum size, and egg white protein concentration on egg white antimicrobial activity and to investigate the putative interactions among these factors by conducting a complete factorial design analysis. The behavior of Salmonella Enteritidis and Escherichia coli was studied after precultivation in tryptic soy broth and Luria-Bertani broth, respectively, using three different egg white protein concentrations (0, 10, and 100%), five temperatures (37, 40, 42, 45, and 48°C), two pHs (7.8 and 9.3), and six inoculum levels (3 to 8 log CFU/ml). The essential role of temperature was identified. An inverse relationship was observed between bacterial growth and an increase in temperature. The role of egg white proteins was clearly demonstrated. In the absence of egg white proteins, bacterial growth occurred under most incubation conditions, whereas the presence of 10 and 100% protein produced bacteriostatic or bactericidal effects. The interaction between temperature and protein concentration was significant. At the highest tested temperatures, proteins were less involved in the bactericidal effect. Bacterial destruction was higher at pH 9.3 than at pH 7.8. Under our experimental conditions, Salmonella Enteritidis was more resistant to inactivation by egg white than was E. coli.
authors.affiliation: AGROCAMPUS Ouest, UMR1253 Science et Technologie du Lait et de l'Œuf, F-35042 Rennes, France.
authors.forename: Maria
authors.initials: M
authors.lastname: Alabdeh
authors.forename: Valérie
authors.initials: V
authors.lastname: Lechevalier
authors.forename: Françoise
authors.initials: F
authors.lastname: Nau
authors.forename: Michel
authors.initials: M
authors.lastname: Gautier
authors.forename: Marie-Françoise
authors.initials: MF
authors.lastname: Cochet
authors.forename: Fabienne
authors.initials: F
authors.lastname: Gonnet
authors.forename: Sophie
authors.initials: S
authors.lastname: Jan
authors.forename: Florence
authors.initials: F
authors.lastname: Baron
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004305:Dose-Response Relationship, Drug; D004527:Egg Proteins / Q000494:pharmacology*; D004529:Egg White; D004531:Eggs / Q000382:microbiology*; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D005506:Food Contamination / Q000517:prevention & control; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D005519:Food Preservation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests; D012477:Salmonella enteritidis / Q000187:drug effects* / Q000254:growth & development; D013696:Temperature
chemical_list: D000900:Anti-Bacterial Agents; D004527:Egg Proteins