Changes in Eggshell Surface Microstructure after Washing with Cetylpyridinium Chloride or Trisodium Phosphate

The effects of egg-washing chemicals on microstructural changes of the eggshell were examined. Fresh-laid eggs were washed with solutions of cetylpyridinium chloride (CPC) at 10, 50, or 100 ppm, or trisodium phosphate (TSP) at 0.5, 1.0, or 5.0% and changes in the shell surface were examined using scanning electron microscopy (SEM). As the concentration of CPC increased, the eggshell surface became pitted and the cuticle layer became thinner. TSP caused the cuticle layer to fissure and flake and even cuticle-free areas were observed at 5.0%. When the porosity of eggs was measured by using the blue lake staining method, there were significant differences between control and TSP- or CPC-washed eggs as observed by SEM. These results suggest that depending on the types of chemicals used in the wash water, different microstructural changes occur in eggshell surfaces, and the more damaged eggshell surfaces allow more bacterial penetration.