Inactivation of Salmonella Enteritidis on Hatchery and Table Eggs Using a Gas-phase Hydroxyl-Radical Process

Area of Science:

• Food Safety and Microbiology
• Environmental Science and Engineering
• Agricultural Science

Background:

• Eggs are a significant transmission vehicle for Salmonella Enteritidis, posing risks to both hatchery chicks and consumers.
• Current decontamination methods, such as egg washing, have limitations in efficacy and potential for cross-contamination.

Purpose of the Study:

• To evaluate the efficacy of a gas-phase hydroxyl-radical process for decontaminating hatchery and table eggs.
• To determine optimal treatment parameters for Salmonella reduction without compromising egg quality or safety.

Main Methods:

• Developed a continuous hydroxyl-radical reactor using UV-C lamps, hydrogen peroxide (H₂O₂) mist, and ozone gas.
• Optimized treatment conditions (H₂O₂ concentration, flow rate, UV-C dose, ozone level, treatment time) for a >5 log CFU/egg reduction of Salmonella.
• Assessed impacts on egg quality metrics (Haugh value, yolk index, pH) and cuticle integrity over 35 days.
• Evaluated effects on fertilized egg hatching rates and observed for defects.

Main Results:

• A treatment of 2% v/v H₂O₂, 30 mL/min, 19 mJ/cm² UV-C dose, 20 ppm ozone, and 10s achieved >5 log CFU/egg reduction of Salmonella.
• No negative impact on egg quality metrics or cuticle integrity was observed post-treatment.
• Hatching rates of treated fertilized eggs were comparable to controls (75% vs. 71-79%), with no observed defects.
• Hydroxyl-radical treatment significantly outperformed conventional egg washing (2.76 log CFU/egg reduction).

Conclusions:

• Gas-phase hydroxyl-radical treatment is a highly effective and safe method for decontaminating both hatchery and table eggs against Salmonella Enteritidis.
• The process is compatible with existing industry egg washing practices and offers a significant improvement in pathogen reduction.
• This technology represents a valuable preventative control strategy to enhance food safety in the egg industry.