C N Tango1,2, J H Park1, D H Oh1. 1. Department of Bioconvergence Science and Technology, College of Agriculture and Life Science, Kangwon National University, Chunchon, Korea. 2. Department of Chemistry and Agricultural Industries, Faculty of Agronomy, University of Kinshasa, Kinshasa, D.R. Congo.
Abstract
AIMS: To gain an understanding of the growth kinetics of Staphylococcus aureus to ensure the safety of pork, and to develop a predictive growth model of Staph. aureus in raw pork, ham and sausage pork under specific storage time and temperature conditions. METHODS AND RESULTS: Growth of Staph. aureus was evaluated at 5-40°C using 5-6 replicates in each sampling time in order to capture experimental variability. Growth curves were fit to Baranyi model to estimate Lag time (λ) and maximum growth rate (μmax). The effect of temperature on λ and μmax was modelled using natural logarithm of λ and square root of μmax. The variability between repetitions was higher at 15, 20 and 40°C than observed at 25, 30 and 35°C. After only 3 and 2 days of storage at 5 and 10°C, respectively, Staph. aureus populations decreased to limit of detection (≤1 log CFU g(-1) ). Staphylococcus aureus populations on ham presented higher μmax in comparison to those grown on raw pork and sausage. Linear regression lines showed that Staph. aureus populations in ham grew faster than those observed in sausage and raw pork. Staph. aureus presented a theoretical minimum growth temperature (Tmin ) depending on the processed pork products, which were different from in raw pork. CONCLUSION: Staphylococcus aureus model predicts faster growth in ham compared to raw pork and sausage. The validation of models showed good predictions, suggesting that the developed models are useful in estimating growth kinetics of Staph. aureus in different pork products. SIGNIFICANCE AND IMPACT OF THIS STUDY: Established here is a data-driven, in silico model on Staph. aureus growth kinetics on different pork products. The model is extensively validated by experiments and simulations and further supported by comparisons to previous modelling efforts in other species.
AIMS: To gain an understanding of the growth kinetics of Staphylococcus aureus to ensure the safety of pork, and to develop a predictive growth model of Staph. aureus in raw pork, ham and sausage pork under specific storage time and temperature conditions. METHODS AND RESULTS: Growth of Staph. aureus was evaluated at 5-40°C using 5-6 replicates in each sampling time in order to capture experimental variability. Growth curves were fit to Baranyi model to estimate Lag time (λ) and maximum growth rate (μmax). The effect of temperature on λ and μmax was modelled using natural logarithm of λ and square root of μmax. The variability between repetitions was higher at 15, 20 and 40°C than observed at 25, 30 and 35°C. After only 3 and 2 days of storage at 5 and 10°C, respectively, Staph. aureus populations decreased to limit of detection (≤1 log CFU g(-1) ). Staphylococcus aureus populations on ham presented higher μmax in comparison to those grown on raw pork and sausage. Linear regression lines showed that Staph. aureus populations in ham grew faster than those observed in sausage and raw pork. Staph. aureus presented a theoretical minimum growth temperature (Tmin ) depending on the processed pork products, which were different from in raw pork. CONCLUSION: Staphylococcus aureus model predicts faster growth in ham compared to raw pork and sausage. The validation of models showed good predictions, suggesting that the developed models are useful in estimating growth kinetics of Staph. aureus in different pork products. SIGNIFICANCE AND IMPACT OF THIS STUDY: Established here is a data-driven, in silico model on Staph. aureus growth kinetics on different pork products. The model is extensively validated by experiments and simulations and further supported by comparisons to previous modelling efforts in other species.