Rapid growth of Salmonella enteritidis in egg white reconstituted from industrial egg white powder.
The aim of this study was to evaluate the consequences of the egg white-drying process on egg white ability to limit Salmonella Enteritidis growth in addition to the elucidation of the factors involved. We observed rapid growth of Salmonella Enteritidis inoculated in egg white reconstituted from industrial powder in comparison with that observed in liquid egg white collected in the laboratory: Salmonella cell counts rose from 10(3) to 10(8) cells/ml of egg white from powder during 24 h incubation at 30 degrees C. This rapid growth was observed in powder from all egg-breaking factories investigated, and it was comparable to that observed in optimum medium (tryptone soy broth). In view of the mechanism of egg white resistance and the major role played by iron availability and by ovotransferrin, we investigated several hypotheses to explain this rapid growth: iron provided during the drying process and/or denaturation of protein (especially ovotransferrin). The rapid growth observed in egg white reconstituted from powder was in relation to egg white protein denaturation and especially ovotransferrin denaturation during powder pasteurization that enhanced the availability of iron necessary for Salmonella growth. The major role played by ovotransferrin and iron deficiency on Salmonella growth in egg white was illustrated in this study.
Baron
F
F
Laboratoire de Technologie Alimentaire, Ecole Nationale Supérieure Agronomique, Rennes, France. baron@epi.roazhon.inra.fr
Gautier
M
M
Brulé
G
G
D000818:Animals; D002645:Chickens; D015169:Colony Count, Microbial; D003207:Conalbumin / Q000737:chemistry; D003470:Culture Media; D003890:Desiccation; D004529:Egg White / Q000382:microbiology*; D004530:Egg Yolk / Q000382:microbiology; D005519:Food Preservation; D005525:Food-Processing Industry; D007501:Iron / Q000032:analysis; D011489:Protein Denaturation; D012477:Salmonella enteritidis / Q000254:growth & development*
D003470:Culture Media; D003207:Conalbumin; D007501:Iron