Development of Best Practices for Shell Egg Disinfection Based upon Efficacy and Egg Quality

This study was conducted to compare current commercial egg sanitizers to new technologies developed to improve egg safety and quality. Objectives included: 1) conduct a survey on current industry egg washing practices along with a microbial survey; 2) assess the efficacy of chlorine, quaternary ammonium compounds (QAC), peracetic acid alone or in combination with ultraviolet (UV) light and hydrogen peroxide (H2O2) (3.5%) in combination with UV light as post-wash sanitizers against aerobic plate counts (APC) and Salmonella Enteritidis (SE) inoculation; 3) conduct a consumer acceptability test to evaluate the influence of chlorine, QAC, and H2O2 and UV light using a 9-point hedonic test; and 4) investigate the effectiveness of H2O2 and UV light applied to eggs prior to washing on APC and the number of dirty eggs.

Results from the egg processing survey indicated that chlorine was the most frequently used sanitizer (81.7%) in the United States and most egg processors are operating in-line type facilities. Moreover, most facilities are not performing any egg treatment prior to washing, and very little in-plant microbiological monitoring was being conducted. The microbial survey indicated that 15 out of 18 visits had significantly less APC in post wash versus prewash eggs, and 11 out of 18 had significantly less APC in the final sanitizer than in the post wash stage. However, mean APC ranges after sanitization were 1.0 to 3.0 log_10 cfu/egg.

In laboratory trials evaluating the effectiveness of various egg sanitization treatments, the combination of H_(2)O_(2) and UV light had the lowest eggshell APC (1.30, 1.05, and 1.10 log_10 cfu/egg) at d 0, 7, and 14, respectively, of storage among all treatments. No differences in overall consumer acceptability were determined among the treatments. However, chlorine-treated eggs received a higher score for texture compared to the other treatments. The combination of H_(2)O_(2) and UV light prior to egg washing resulted in higher percentage of Grade A eggs and lower APC (2.1 log_10 cfu/egg). Therefore, this new technology can be used as an effective sanitizer to improve the quality and safety of shell eggs.