Antimicrobial Efficacy of Aqueous Ozone and Ozone-Lactic Acid Blend on Salmonella -Contaminated Chicken Drumsticks Using Multiple Sequential Soaking and Spraying Approaches

Ozone (O ) is an attractive alternative antimicrobial in the poultry processing industry. The optimal operational conditions of O for improving food safety concerns are poorly understood. The main objective of this study was therefore to characterize the microbial killing capacity of aqueous O and O -lactic acid blend (O -LA) at different operational conditions on chicken drumsticks contaminated with high load using sequential soaking and spraying approaches. Four hundred forty-eight chicken drumsticks (280-310 g) were soaked into two-strain cocktail, and the initial load on the surface of the skin was 6.9-log cell forming unit (CFU)/cm [95% confidence interval (CI), 6.8-7.0]. The contaminated drumsticks were then sequentially (10×) soaked and sprayed with aqueous O (8 ppm) and O -LA. Following O exposure, quantitative bacterial cultures were performed on the post-soaking and post-spraying water, skin surface, and subcutaneous (SC) of each drumstick using 3M Petrifilm Rapid Aerobic Count Plate (RAC) and plate reader. The average killing capacity of aqueous O /cycle on the skin surface was 1.6-log /cm (95% CI, 1.5-1.8-log /cm ) and 1.2-log /cm (95% CI, 1.0-1.4-log /cm ), and it was 1.1-log /cm (95% CI, 0.9-1.3-log /cm ) and 0.9-log /cm (95% CI, 0.7-1.1-log /cm ) in SC for soaking and spraying approaches, respectively. Six sequential soaking and seven sequential spraying cycles with ozonated water of 8 ppm reduced the heavy load below the detectable limit on the skin surface and SC of drumsticks, respectively. Addition of LA seems to increase the microbial killing capacity of aqueous O with average differences of 0.3-log /cm ( = 0.08) and 0.2-log /cm ( = 0.12) on the skin surface using soaking and spraying approaches, respectively. Aqueous O did not cause any significant changes in the drumstick skin color. The load of < 4.5-log /cm was a strong predictor for the reduction rate ( < 0.001, = 0.64). These results provide important information that helps the poultry processing facilities for selecting the optimal operational strategy of O as an effective antimicrobial.