Studies on the growth of Salmonella in table eggs under different storage temperatures

In Germany salmonellosis is one of the most common foodborne infections in humans. Contaminated table eggs are one of the main sources of the infection. The aim of the study was to obtain experimental data on the impact of temperature conditions on the behaviour of Salmonella Enteritidis (SE) in table eggs which may occur under practical conditions. For this purpose, 170 fresh eggs were contaminated by inoculating SE into the albumen of intact eggs and eggs were stored at different temperatures (group A: 5 degrees C; group B: 25 degrees C; group C: 25 degrees C/5 degrees C in alternating sequences of three-day intervals). Every six days, qualitative and quantitative examinations to detect SE were carried out during the following 30 days. Salmonella, which were inoculated into the albumen could be detected over the whole study period, i.e. it was not inactivated; however, only during storage at 5 degrees C, there was no growth of SE. By qualitative examination, SE could be detected in the egg yolk in all groups within six days after inoculation. By quantitative testing, a considerable bacterial growth was confirmed during storage at 25 degrees C or changing temperatures 125 degrees C/5 degrees C). By alternating storage temperatures, the highest migration rate into the yolk could be detected (64 %), but changing temperatures had no additional effect on the detection or concentration of Salmonella in fresh eggs. This study shows that eggs should be chilled immediately after laying; a storage temperature of <= 5 degrees C is recommended.