Investigations on the Effect of Ozone as a Disinfectant of Egg Surfaces

The feasibility of gaseous ozone to reduce the number of microorganisms on the shell surface, of Salmonella Enteritidis (S. E.) in particular, of avian hatching eggs was investigated. Shell eggs were externally contaminated with S. E. to contain either 10(2)-10(4) or 10(5)-10(6) cfu/shell. Subsequently, the eggs were exposed to several ozone concentrations ranging from 0.5% to 5% wt/wt in combination with two relative humidities (< 30, > 70%) at room temperature. Exposure times varied between 20 minutes and 24 hours. A complete inactivation of 10(2)-10(4) cfu S.E./egg shell was reached by using an ozone concentration of 1% (wt/wt) for 120 min. Considering higher concentrations of S. E. on the shell ozone treatment caused approximately a 6 log(10) reduction. This demonstrates that gaseous ozonation is suitable for applications in hatcheries provided that high-power ozone generators are available. The parameters should be verified in large ozone cabinets.