Effect of sequential treatments with sodium dodecyl sulfate and citric acid or hydrogen peroxide on the reduction of some foodborne pathogens on eggshell.

The aim of this study was to investigate the effect of sodium dodecyl sulfate (SDS), citric acid, and hydrogen peroxide (H2 O2 ), alone or in combination, on reducing the population of four foodborne pathogens, including Escherichia coli , Listeria monocytogenes , Salmonella typhimurium , and Staphylococcus aureus on eggshells. In each series of tests, eight fresh eggs were inoculated with each bacterial strain by being immersed in a bacterial suspension and exposed to SDS (1.5%), H2 O2 (0.5%), citric acid (1%), or sequential treatments with SDS + citric acid and SDS + H2 O2 . Viable cell counts were made and the bacterial concentrations results compared to pre-treatment levels. Results showed that all washing solutions except citric acid significantly (P<0.05) reduced the concentration of all tested bacteria (~2-4 log reductions). The sensitivity of S . typhimurium and E. coli to SDS and H2 O2 was similar (~2.5 log reduction). Listeria monocytogenes (4.1 Log reduction) and S. aureus (4.3 Log reduction) were more sensitive to SDS and H2 O2 , respectively. The combination of SDS and citric acid or H2 O2 in comparison to SDS alone, generally did not produce significant additive reductions in the viability of the bacteria on eggshells. These data suggest that SDS potentially could be used alone or in combination with citric acid or H2 O2 as an effective and inexpensive method to reduce bacteria, such as L. monocytogenes , on eggshells. Additionally, application of SDS may be useful for bacterial decontamination of other materials and surfaces in food industries.