Validation of a pickling process for controlling pathogens associated with hard-cooked eggs

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 (20min) to obtain a population of ≥6.55 log₁₀ cfu/g, treated with a prepickling solution (∼22C, 48h) and followed by a treatment with a packing solution (∼22C, 48h). Microbial populations on eggs and in the pickling solutions, water activity (A_w) 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 96h (22C). Pathogens associated with polyethylene terephthalate jars and subjected to packing solution for 72h could not be recovered, resulting in a >6.70 log₁₀ cfu/mL reduction. During pickling, the pH of pickling solutions increased, while pH and A_w 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.