Modeling the Growth of Salmonella in Raw Poultry Stored under Aerobic Conditions

Abstract

The presence of Salmonella in raw poultry is a well-recognized risk factor for foodborne illness. The objective of this study was to develop and validate a mathematical model that predicts the growth of Salmonella in raw poultry stored under aerobic conditions at a variety of temperatures. One hundred twelve Salmonella growth rates were extracted from 12 previously published studies. These growth rates were used to develop a square-root model relating the growth rate of Salmonella to storage temperature. Model predictions were compared to growth rate measurements collected in our laboratory for four poultry-specific Salmonella strains (two antibiotic-resistant and two nonresistant strains) inoculated onto raw chicken tender-loins. Chicken was inoculated at two levels (103 CFU/cm2 and ≤ 10 CFU/cm2) and incubated at temperatures ranging from 10 to 37°C. Visual inspection of the data, bias and accuracy factors, and comparison with two other published models were used to analyze the performance of the new model. Neither antibiotic resistance nor inoculum size affected Salmonella growth rates. The presence of spoilage microflora did not appear to slow the growth of Salmonella. Our model provided intermediate predicted growth rates when compared with the two other published models. Our model predicted slightly faster growth rates than those observed in inoculated chicken in the temperature range of 10 to 28°C but slightly slower growth rates than those observed between 30 and 37°C. Slightly negative bias factors were obtained in every case (−5to −3%); however, application of the model may be considered fail-safe for storage temperatures below 28°C.