Evaluation of Egg Wash Sanitizers to Reduce Salmonella Contamination on and in Turkey Eggs


to Reduce Salmonella Contamination on and in Turkey Eggs

Institution: Cargill, Inc.

Principal Investigator:

Dr. Ted Brown
Cargill, Inc.
Cargill Scientific Services
300 West First Street North
Wichita, KS 76202

Salmonella remains the number one cause of foodborne illness in the U.S., which causes an economic burden for the poultry industry as well as public concern for the consumers. The poultry industry must be diligent at all steps of processing to reduce Salmonella risk, including interventions for hatch eggs. Salmonella is frequently found on hatch eggs even after the sanitization process. Chlorine is widely used by turkey breeders for egg sanitization. Although it can be an effective sanitizer, there are drawbacks to using it, such as: 1) chlorine dissociates quickly with presence of organic loads, 2) it can be very corrosive to equipment, and 3) ensuring chlorine is at effective levels requires strict management practices. While there are other well-known and more effective sanitizers available, many sanitizers can damage the egg cuticle and allow more bacteria to enter the egg. Prior studies have evaluated non-chlorine sanitizers, such as peracetic acid (PAA) and peroxide, as egg sanitizers. However, none of these trials evaluated the effect on the cuticle layer to ensure hatchability. There is a critical need to find an improved egg sanitization process to reduce Salmonella contamination in breeder eggs but not negatively impact hatchability. This project evaluated several new antimicrobials on the market as egg sanitization chemicals and assessed their impact on the egg cuticle.

Objective 1 used a Salmonella inoculation trial to determine the most effective hatch egg sanitizers to reduce Salmonella contamination on the external egg surface. The sanitizers evaluated included thymol, PAA, bromine, peroxide and quaternary ammonium. Chlorine (commonly used in the industry today) was included as a positive control, and an unwashed set of eggs served as the negative control. Sanitization efficacy was evaluated by inoculating the eggshell with Salmonella, treating the egg with each sanitizer wash treatment, shaking the washed eggs in a bag with sterile media, and measuring contamination by plating the rinsate and quantifying aerobic plate counts and Salmonella (Log CFU/egg by enumeration).

Objective 2 assessed the hatch egg sanitizers from Objective 1 on their ability to cause potential cuticle damage and allow Salmonella to penetrate the egg. Bacterial penetration into the egg was evaluated by inoculating the eggshell with Salmonella, treating the egg with each sanitizer wash treatment, and measuring transmission by plating the internal egg contents and quantifying Salmonella (Log CFU/g by enumeration).  Egg penetration was also evaluated by a Blue Lake Dye test performed at one day of storage.

The peroxide product proved to be the most effective egg sanitizer at reducing Salmonella prevalence on the egg surface by more than 73%. Chlorine, quaternary ammonia, PAA and bromine all proved to be equally effective egg sanitizers by reducing Salmonella prevalence detected on the egg surface. PAA and bromine reduced Salmonella by 34% and 30%, respectively. This was slightly less than chlorine (reduction of 43%) and quaternary ammonia (reduction of 37%). The thymol product was the least effective sanitizer assessed in the study (only reduced Salmonella prevalence by less than 5%). All treatments reduced Salmonella levels on the surface of the inoculated eggs by three logs when compared to the unwashed treatment. When assessing aerobic plate counts, all treatments performed significantly better than thymol and bromine. Peroxide and quaternary ammonia were most effective at reducing aerobic plates counts, which demonstrated a 4.25 and 4.33 Log CFU/egg reduction, respectively.

The two methods utilized to assess the cuticle during the trial generated results demonstrating the sanitizers tested in this trial did not damage the cuticle and Salmonella did not penetrate the egg. A true hatchability trial should be completed to ensure hatch rates are not affected by the sanitizers assessed in this study.

In the short-term, this project produced updated information on new and current egg sanitizing washes to guide industry on the best process to mitigate Salmonella contamination in and on hatch eggs during the washing process at breeder facilities. Findings from this work are of direct relevance across the turkey industry, as well as the broader poultry industry.