Inhibitory effects of sucrose fatty acid esters on survival of Yersinia enterocolitica on eggshell surface and use of blue lake as indicator of bacterial penetration into eggs

Aims:  To determine the effectiveness of sucrose monolaurate (SML) and sucrose monocaprate (SMC), alone and in combination with ethylenediaminetetraacetic acid (EDTA), propionic acid (PA) or citric acid (CA) in reducing mesophilic aerobic bacteria (MAB) and Yersinia enterocolitica O:9 populations on eggshells and their damage potential on the microstructure of shell cuticle.
Methods and Results:  Uninoculated eggs and eggs submerged in a solution of Y. enterocolitica were immersed in solutions of the various treatments. MAB and Y. enterocolitica counts on the surface of the eggs were carried out before and after treatment. MAB counts decreased less than 2 logs on uninoculated eggshells irrespective of treatment and reductions of 3·2 and 3·0 logs of Y. enterocolitica were obtained with 1000 μg ml⁻¹ SML plus 0·1% CA or 1000 μg ml⁻¹ SML plus 600 μg ml⁻¹ EDTA solutions, respectively. Y. enterocolitica 2/O:9 was recovered from natural microflora. Use of blue lake staining revealed minimal damage to the shells from the washing treatments.
Conclusions:  SML and SMC at 1000 μg ml⁻¹ combined with CA or EDTA could be effective in reducing Y. enterocolitica on eggshells with a minimal risk of later bacterial recontamination.
Significance and Impact of the Study:  Eggs are a recognized vehicle for transmission of Y enterocolitica although a prevalence of only 2·7% was detected in this study. Washing eggs in solutions containing SML or SMC could eliminate Y. enterocolitica contamination of egg shells.