Abstract
Ozone (O3) is an attractive alternative antimicrobial in the poultry processing industry. The optimal operational conditions of O3 for improving food safety concerns are poorly understood. The main objective of this study was therefore to characterize the microbial killing capacity of aqueous O3 and O3–lactic acid blend (O3–LA) at different operational conditions on chicken drumsticks contaminated with high Salmonella load using sequential soaking and spraying approaches. Four hundred forty-eight chicken drumsticks (280–310 g) were soaked into two-strain Salmonella cocktail, and the initial load on the surface of the skin was 6.9-log10 cell forming unit (CFU)/cm2 [95% confidence interval (CI), 6.8–7.0]. The contaminated drumsticks were then sequentially (10×) soaked and sprayed with aqueous O3 (8 ppm) and O3–LA. Following O3 exposure, quantitative bacterial cultures were performed on the post-soaking and post-spraying water, skin surface, and subcutaneous (SC) of each drumstick using 3MTM PetrifilmTM Rapid Aerobic Count Plate (RAC) and plate reader. The average killing capacity of aqueous O3/cycle on the skin surface was 1.6-log10/cm2 (95% CI, 1.5–1.8-log10/cm2) and 1.2-log10/cm2 (95% CI, 1.0–1.4-log10/cm2), and it was 1.1-log10/cm2 (95% CI, 0.9–1.3-log10/cm2) and 0.9-log10/cm2 (95% CI, 0.7–1.1-log10/cm2) 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 Salmonella 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 O3 with average differences of 0.3-log10/cm2 (P = 0.08) and 0.2-log10/cm2 (P = 0.12) on the skin surface using soaking and spraying approaches, respectively. Aqueous O3 did not cause any significant changes in the drumstick skin color. The Salmonella load of < 4.5-log10/cm2 was a strong predictor for the reduction rate (P < 0.001, R2 = 0.64). These results provide important information that helps the poultry processing facilities for selecting the optimal operational strategy of O3 as an effective antimicrobial.
Highlights
Chicken meat is the second most popular meat in the world, which accounts for ∼30% of meat production preceded by pork with 38% of the total meat production
Five sequential soaking cycles were sufficient to reduce the heavy bioload of aSTC (6.9-log10/ml) below the detectable limit on the skin surface (Supplementary Table S1 and Figure 1A)
O3–lactic acid blend (O3–lactic acid (LA)) blend showed higher aSTC killing capacity than aqueous O3 with a total average difference of 0.3-log10/cm2 (P = 0.08), where four sequential soaking cycles were sufficient to reduce the heavy bioload of aSTC below the detectable limit (Supplementary Table S1 and Figure 1A)
Summary
Chicken meat is the second most popular meat in the world, which accounts for ∼30% of meat production preceded by pork with 38% of the total meat production. In the United States, poultry meat is the most popular consumed meat, and the consumption has steadily increased in recent years. The annual poultry meat consumption per capita has increased from 27 lb in 1970 to 60 lb in 2005 (National Chicken Council, 2011). The reasons for the popularity of this kind of meat are the competitive price, absence of cultural and religious obstacles, fast preparation, low fat content, and the high nutritional value (Food and Agriculture Organization of the United Nations [FAO], 2014). In 2009, 12% of broilers were consumed as whole birds, and 42% as parts (National Chicken Council, 2011). The new standards include culture for foodborne pathogens at the end of the chilling line and in the cut-up room (United States Department of Agriculture, Food Safety, and Inspection Service, 2015)
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