An experimental validated in silico model to assess Staphylococcus aureus growth kinetics on different pork products.

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.

Synergetic effect of combined fumaric acid and slightly acidic electrolysed water on the inactivation of food-borne pathogens and extending the shelf life of fresh beef.

AIMS: To evaluate synergetic effect of slight acidic electrolysed water (SAEW) and fumaric acid (FA) on inactivation of total viable count (TVC) and Staphylococcus aureus, Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella Typhimurium in fresh beef and to study shelf life and sensory quality of beef. METHODS AND RESULTS: Inoculated samples was dipped for 1, 3 and 5 min and immersed at 25, 40 and 60°C in SAEW, strong acidic electrolysed water (StAEW) and SAWE + FA. Treated meat was air-packaged and stored at 4 or 10°C. During storage, sampling was performed at 2-day intervals for microbiological and sensory changes. TVC was decontaminated at 40°C for 3 min by more than 3·70 log CFU g(-1) , and examined pathogens were reduced by more than 2·60 log CFU g(-1) with SAEW + FA treatment. This treatment prolonged shelf life of beef meat up to 9 and 7 days when stored at 4 and 10°C, respectively. CONCLUSION: The combined treatment of SAEW + FA showed greater bactericidal effect and prolonged shelf life compared with individual treatments. SIGNIFICANCE AND IMPACT OF THE STUDY: Combined treatment of SAEW and FA can be a suitable hurdle technology reducing bacteria in fresh beef, substantially enhancing their microbial safety and decreasing pathogens growth during storage.