Effects of disinfectants and spray washing on Salmonella Enteritidis contamination on the shell surface of eggs

The effects of disinfectants and antibacterial chemicals used in food production on Salmonella Enteritidis contamination on the shell surface of eggs were examined from the viewpoint of prevention of Salmonella foodborne disease due to intact eggs and egg products (whole egg, eggwhite, yolk, sugared yolk, salted yolk, etc.). Eggs artificially contaminated with S. Enteritidis in various ways were immersed in a solution of sodium hypochlorite, organic acid (fumaric acid or acetic acid) or trisodium phosphate for 2 to 20 min. After drying, these eggs were stored at 8 or 25 degrees C for 14 days. S. Enteritidis on the shell surface was evaluated by direct plating on DHL agar (direct method) and by enrichment with EEM broth (enrichment method) at intervals of 0 (examined immediately), 1, 3, 7 and 14 days. The number of eggs contaminated with S. Enteritidis was decreased effectively by storage for 7 to 14 days at 8 degrees C or 25 degrees C after immersion in 5 similar to 15% trisodium phosphate solution. Eighty to one hundred percent of eggs examined were free from S. Enteritidis by the direct method, whereas 65 similar to 87% of eggs were uncontaminated according to the enrichment method. The number of S. Enteritidis on the shell surface of eggs artificially contaminated with the organism in 2% whole eggs and 1% gelatin was decreased effectively by spray washing with fresh water after immersion in 1 similar to 2% trisodium phosphate solution. From these results, trisodium phosphate may be effective for removing Salmonella from the shell surface of eggs during washing of eggs in grading and packing centers and in egg-product plants.