The effect of a commercial UV disinfection system on the bacterial load of shell eggs

Abstract

Aims: To study the effect of UV irradiation on the bacterial load of shell eggs and of a roller conveyor belt.

Methods and results: The natural bacterial load on the eggshell of clean eggs was significantly reduced by a standard UV treatment of 4.7 s; from 4.47 to 3.57 log CFU per eggshell. For very dirty eggs no significant reduction was observed. Eggs inoculated with Escherichia coli and Staphylococcus aureus (4.74 and 4.64 log CFU per eggshell respectively) passed the conveyor belt and were exposed to UV for 4.7 and 18.8 s. The reduction of both inoculated bacteria on the eggshell was comparable and significant for both exposure times (3 and 4 log CFU per eggshell). Escherichia coli was reduced but still detectable on the conveyor rollers. The internal bacterial contamination of eggs filled up with diluent containing E. coli or S. aureus was not influenced by UV irradiation.

Conclusions: There is a significant lethal effect of UV irradiation on the bacterial contamination of clean eggshells and recent shell contamination, contamination of rollers can be controlled and the internal contamination of eggs is not reduced.

Significance and impact of the study: The penetration of UV into organic material appears to be poor and UV disinfection can be used as an alternative for egg washing.