IN a recently completed research project funded by the U.S. Poultry & Egg Foundation, researchers investigated current and alternative practices for shell egg sanitization.
Drs. Craig Coufal and Christine Alvarado of Texas A&M University surveyed egg processors across the U.S. to determine current practices and costs of shell egg sanitization. In addition, they conducted a microbial survey to evaluate the effectiveness of current practices.
Their research also involved evaluating the effectiveness of prewash egg disinfection procedures, determining the efficacy and quality parameters of current methods compared to alternative methods and conducting an economic analysis to compare current and alternative methods of shell egg sanitization.
Their findings will provide guidance in formulating future best practices for the industry, the foundation said.
Coufal and Alvarado said salmonella contamination of shell eggs and subsequent recalls in 2010 resulted in economic losses to the egg industry and increased consumer concerns about the safety of eggs.
Treatment of eggs with chlorine or quaternary ammonium (QAC) sprays as a final disinfection step following washing has been the standard for egg processing in the U.S. for decades, the researchers explained.
The use of ultraviolet light (UV) as a final disinfection step for shell egg processing has been approved by the U.S. Department of Agriculture but has not gained widespread use in the U.S. egg industry, they added.
Coufal and Alvarado said previous research has indicated that none of those egg sanitization processes completely disinfect the surface of shell eggs during processing. As a result, more effective shell sanitization technologies are needed to help ensure the safety of shell eggs and egg products.
The overall goal of their project was to develop and evaluate improved egg sanitization processes for shell eggs to enhance food safety.
The project's specific objectives were to: (1) survey egg processors across the U.S. to determine current practices and costs of shell egg sanitization, (2) conduct a microbial survey of egg processing facilities to evaluate current sanitization of shell eggs, (3) evaluate the effectiveness of prewash egg disinfection procedures, (4) determine efficacy and quality parameters of current methods of egg sanitization compared to alternative technologies and (5) conduct an economic analysis to compare current and alternative methods for the sanitization of shell eggs.
The survey of egg processors across the U.S. indicated that egg sanitization practices are quite standardized across the egg industry, Coufal and Alvarado reported, noting that this is not surprising, since 77% of respondents indicated that they were processing eggs under inspection (presumably by USDA) and must, therefore, follow set guidelines.
Coufal and Alvarado noted that 83% of egg processors are using a chlorine solution rinse in the final disinfection step. Results also indicate that few processors apply a sanitization process prior to egg washing or conduct microbiological monitoring.
Eggs sampled from six egg packing plants in Texas verified that currently used egg sanitization methods significantly reduce the microbial load on eggshells but usually leave a low level of bacteria remaining on the shell's surface, Coufal and Alvarado said.
They conducted four trials to evaluate the use of hydrogen peroxide in combination with UV light to treat eggs prior to washing. Results indicated that treatment prior to washing resulted in fewer dirty eggs following washing, and visibly clean eggs after washing had lower microbial counts if they were treated prior to washing, Coufal and Alvarado reported.
Several experiments were conducted to compare the effectiveness of eggshell disinfectants that are currently used in the egg industry to the alternative methods of peracetic acid (PAA), PAA in combination with UV light and hydrogen peroxide in combination with UV light.
Coufal and Alvarado said PAA was found to be more effective than chlorine but less effective than QAC. Hydrogen peroxide with UV light was the most effective sanitizer, resulting in zero microbial counts on most eggshells.
A sensory panel evaluation indicated that eggs treated with hydrogen peroxide and UV light were perceived by consumers to be equal to untreated eggs and eggs treated with QAC, the researchers said, but eggs treated with chlorine received the highest scores for taste and texture.
While hydrogen peroxide with UV light was found to be a superior eggshell disinfectant compared to methods currently used in the egg industry, the cost is greater, Coufal and Alvarado noted.