VALIDATION OF A PICKLING PROCESS FOR CONTROLLING PATHOGENS ASSOCIATED WITH HARD-COOKED EGGS

Abstract

ABSTRACT This study was conducted to determine if foodborne pathogens could be inactivated on hard-cooked eggs (HCEs) subjected to a pickling process. Commercially processed, HCEs were inoculated with a pathogen cocktail consisting of ∼8 log10 cfu/mL of Salmonella spp., Staphylococcus aureus, Listeria monocytogenes and Escherichia coli O157:H7 (20 min) to obtain a population of ≥6.55 log10 cfu/g, treated with a prepickling solution (∼22C, 48 h) and followed by a treatment with a packing solution (∼22C, 48 h). Microbial populations on eggs and in the pickling solutions, water activity (Aw) and pH of treated eggs were determined. Results demonstrated that prepickling and packing solutions achieved >4.85 log10 cfu/g reduction for all pathogens on eggs within 96 h (22C). Pathogens associated with polyethylene terephthalate jars and subjected to packing solution for 72 h could not be recovered, resulting in a >6.70 log10 cfu/mL reduction. During pickling, the pH of pickling solutions increased, while pH and Aw of the eggs decreased. This study demonstrates the effect of a pickling process on foodborne pathogens associated with HCEs and may be of interest to regulatory agencies or the egg industry that are interested in validation processes to improve the microbiological safety of this product. PRACTICAL APPLICATIONS Pickling processes have been used for hundreds of years in a variety of commodities and are considered safe and effective food preservation methods. However, very little published information that addresses the effects of pickling on pathogens associated with hard-cooked eggs (HCEs) exists. Regulatory agencies, such as the United States Department of Agriculture (USDA) and U.S. Food and Drug Administration (FDA), may require food processors to validate their pickling processes for pathogen reduction as part of their Hazard Analysis and Critical Control Point plans. Validation of pickling processes may be accomplished by conducting challenge studies with pathogens under laboratory-controlled conditions. Therefore, a challenge study was conducted to determine if a two-step pickling process, applied to HCEs, is effective for reducing pathogens such as Salmonella spp., Staphylococcus aureus, Listeria monocytogenes and Escherichia coli O157:H7. The information from this study may be of interest to the USDA, FDA and egg processors.