Levulinic acid plus SDS treatment to inactivate Salmonella on Poultry and Poultry-Associated Equipment and Facilities

Summary

Coupons composed of five different materials including stainless, polyvinyl chloride, nitrile rubber, glass, and ultra-high molecular weight polyethylene, were tested for the ability of Salmonella biofilms on them. Results revealed that S. Enteritidis biofilms were formed well on all of them. Applying 3% levulinic acid plus 2% SDS as a liquid reduced S. Enteritidis population from 8 log to undetectable levels as deterined by a direct plating method (>7 log reduction) and to 1.7 log (>6 log reduction) within 1 min in coupons composed of stainless, glass, and ultra-high molecular weight polyethylene, and polyvinyl chloride and nitrile rubber, respectively. These coupons with well-formed S. Enteritidis biofilms were further tested by chemical treatment with 3% levulinic acid plus 2% SDS as a foam. Results revealed that the foam remained for more than 20 min in a 50-ml centrifuge tube containing one of the coupons. The treatment reduced S. Enteritidis population from 7 to 8 log to 3 to 4 log within 5 min. A total of 100 chicken cages following the transportation of chickens from growout houses to the slaughterhouse were selected for the chemical treatment studies. Results revealed that the Salmonella isolation rate was 19% (19/100), the fecal coliform population averaged 6.8 CFU/cm2 log (ranged from 3 to 9.3 log CFU/25 cm2) and the total aerobic bacteria count averaged 7.9 log CFU/25 cm2 (ranged from 5.7 to 9.9 log CFU/25 cm2) before chemical treatment. After treatment with 3% levulinic acid plus 2% SDS as a foam, the Salmonella isolation rate was 1% (1/100), the fecal coliform population averaged 1.15 log CFU/25 cm2 (ranged from 0.6 to 3.1 log CFU/25 cm2), a 5.6 log CFU/25 cm2 reduction; and the aerobic bacteria count averaged 4.8 log CFU/cm2 (ranged from 1.6 to 7.5 log CFU/25 cm2), a 3.2 log reduction. A 10 x 10-foot loading area at a poultry slaughterhouse was selected for treatment with 3% levulinic acid + 2% SDS as a foam. Results revealed that the Salmonella isolation rate was 0%, the fecal coliform count averaged 8.0 log CFU/25 cm2 (ranged from 7.5 to 8.6 log FU/25 cm2), and the aerobic bacteria count averaged 8.4 log CFU/25 cm2 (ranged from 7.7 to 9.5 log CFU/25 cm2) before treatment. After treatment the Salmonella isolation rate was 0%, the fecal coliform count averaged 0.78 log CFU/cm2 (ranged from 0.6 to 3.2 log CFU/cm2), a reduction of 7.1 log CFU/cm2; and the aerobic bacteria count averaged 3.6 log CFU/25 cm2 (ranged from 3 to 4.6 log CFU/cm2), a reduction of 4.9 log CFU/cm2. Five chickens with feathers were treated with 3% levulinic acid plus 2% SDS at 21°C for 5 min. Results revealed the Salmonella counts before and after treatment averaged at 8.4 and 1.8 log CFU/9 cm2, respectively; a reduction of 6.6 log CFU/9 cm2. Treatment with 2% levulinic acid and 1% SDS resulted in a substantial reduction of Salmonella populations on the chicken surface, with average Salmonella counts before and after treatment 8.0 and 4.9 log CFU/9 cm2, respectively, for an average reduction of 3.1 log CFU/9cm2.

Situation

Studies have revealed that chickens when they arrive at processing facilities, generally have high populations of bacteria, which can include Campylobacter and/or Salmonella in their viscera and externally on feathers and skin. During processing, such contamination is frequently transferred to processing equipment, other carcasses, and final products. a recent study of the prevalence of Salmonella on surfaces of processing equipment, in water, and on broiler chickens during poultry slaughter revealed a total Salmonella-positive rate of 5.4% (33 of 615), including transport cages (16.7%), boxes (10%), scald water (16.7%), chill water (6.7%), carcasses before evisceration (6.7%), carcasses after chilling (3.3%), fresh legs (10%), frozen wings (13.3%, frozen legs (13.3%), intestines (6.7%), breast and leg skin (10%), and neck skin (6.7%). USDA-FSIS has become increasingly concerned about reduction of Salmonella on fresh poultry. Regulators are requiring that more processing facilities conduct validation and verification of their intervention strategies and provide evidence that their intervention strategies are effective in controlling microbiological hazards (U.S. Department of Agriculture, Food Safety and Inspection Service. 2006. Salmonella verification sample result reporting: agency policy and use in public health protection. Fed. Regist. 71:9772-9777).

Response

Previous studies revealed that surface contamination (skin and feathers) of Salmonella on broilers during grow out and transportation is a primary location of contamination. Our objective for the second year of this project was to develop a practical, effective intervention to reduce Salmonella contamination on poultry skin and feathers during production and transport. Such an intervention must not adversely affect the animal's health and growth rates, and should be environmentally friendly.

Impact

Three treatment approaches were evaluated. The first was to determine Salmonella reduction/elimination in biofilms well-developed on different materials. Treating with 3% levulinic acid plus 2% SDS as a fluid or a foam biofilms of salmonellae on coupons comprised of stainless steel, polyvinyl chloride, nitrile rubber, glass, or ultra-high molecular weight polyethylene reduced Salmonella cell numbers by >5 log within 5 and 20 min, respectively. Chicken treated with a foam formula containing 3% levulinic acid plus 2% SDS sprayed on the surface of chicken cage doors after transportion of chickens reduced Salmonella from 19% (19/100) before treatment to 1% (1/100) after treatment. Fecal coliform counts were 6 to 8 log CFU/9 cm2 before treatment and 2 to 4 log CFU/9 cm2 after treatment, and aerobic plate counts were 7 to 9 log CFU/9 cm2 before treatment and 4 to 6 log CFU/9 cm2 after treatment. Similar results were obtained with this treatment when applied to the loading area. Whole chickens with feathers were contaminated in a suspension (2 L) of 108 S. Enteritidis cells/ml for 1 min and dried in a laminar hood for 30 min. Five chickens were selected as a group for each treatment. Chickens were sampled for Salmonella at five different sites including the left wing, right wing, left breast, right breast, and neck area before and after treatment. Two treatment procedures, including surface spray (with and without electric charge) and soaking in a container containing 72 L of solution at 21° and 55°C, were evaluated for their effects on inactivation of Salmonella. Results revealed that Salmonella counts on chickens treated with water (72 L) only (negative control) at 21°C for 5 min were 6.8 to 8.5 log CFU/9 cm2, whereas counts on chickens treated with 50 ppm calcium hypochlorite (positive control) for 5 min were 7.6 to 8.9 log CFU/9 cm2. Salmonella counts on chickens treated by soaking with 3% levulinic acid plus 2% SDS at 21°C for 5 min were between <1.7 to 2.8 CFU/9 cm2 (a 4-log reduction), whereas counts were 6.0 to 8.8 CFU/9 cm2 for chickens treated with spray (no significant reduction) and between 7.2 to 8.9 CFU/cm2 for chickens sprayed with an electric charge (no significant reduction). Salmonella counts after soaking contaminated chickens in 2% levulinic acid plus 1% SDS solution (72 L) at 21°C for 5 min were between 3.9 to 6.6 CFU/9 cm2 (a 3 log reduction). Increasing the treatment temperature to 55°C had minimal effect on Salmonella reductioon with chickens treated with 3% levulinic acid plus 2% SDS for 5 min of <1.7 to 5.5 log CFU/9 cm2 (ca. a 3 log reduction), whereas Salmonella counts on chickens treated with 50 ppm calcium hypochlorite were 5.9 to 8.3 log CFU/9 cm2 (a 1 log reduction). Treatment of poultry (including feathers and skin) and equipment surfaces with a combination of 3% levulinic acid plus 2% SDS either as a foam or liquid may be used as an effective intervention technology by the poultry industry to control Salmonella and possibly Camylobacter contamination, and reduce the total bacterial load. This includes treatment of chicken surfaces before delivered to processing facilities, the chicken farm environment, chicken transportation cages and vehicles. Results obtained from biofilm studies on chicken cages and whole chickens revealed that the levulinic acid plus SDS treatment when used as either a liquid or foam effectively removed and inactivated Salmonella populations within 5 min. This technology has been licensed by UGARF to HealthPro Brands.

State Issue

Food Safety

Details

• Year: 2009
• Geographic Scope: International
• County: Spalding
• Program Areas:
  • Agriculture & Natural Resources