Microbiological challenges of poultry egg production in the US

Abstract

Over the past 40 years there have been many changes in egg production and processing, as well as, the egg itself. Many of these changes have contributed to the microbial challenges of the egg that we face today. Salmonella enterica serovar Enteritidis (SE) and more recently Salmonella enterica serovar Heidelberg (SH) are the two organisms of most concern associated with eggs. Most U.S. egg producers utilize some type of control programme to ensure egg safety. Many use the United Egg Producers' “5-Start” Food Safety Programme. Commercial egg washing significantly reduced concentrations of aerobic bacteria, yeasts and moulds, Enterobacteriaceae, and E. coli on shell egg surfaces. However, refrigeration of eggs is often identified as one the most critical issues in minimizing the risks associated with Salmonella contamination in eggs. The condensation question always arises any time egg refrigeration is discussed. Moisture often condenses on the shell surface when cold eggs are moved from the cool storage into hot and/or humid conditions. Research has shown that the ability of any microbes present on the shell to penetrate the shell was not increased with egg sweating. Also, heat sensitivity of SE can be induced by exposure to low temperatures. Although low numbers of SE and SH can contaminate eggs via the transovarian or shell penetration route, these small numbers cannot be ignored. Storage at temperatures as low 4°C combined with natural defences does not completely prevent growth. Furthermore, rapid growth occurs at 25°C, so minimal temperature abuse could result in high levels of contamination within eggs. The need for proper management during production, properly controlled storage, cooking and serving is critical.