Thermal inactivation kinetics of Staphylococcus aureus in ground beef – one-step analysis of isothermal and dynamic heating

Authors: OZTURK, SAMET - Oak Ridge Institute For Science And Education (ORISE); Huang, Lihan; Sheen, Shiowshuh; Hwang, Cheng An

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2026
Publication Date: 6/18/2026
Citation: Ozturk, S., Huang, L., Sheen, S., Hwang, C. 2026. Thermal inactivation kinetics of Staphylococcus aureus in ground beef – one-step analysis of isothermal and dynamic heating. Journal of Food Protection. https://doi.org/10.1016/j.ijfoodmicro.2026.111916.
DOI: https://doi.org/10.1016/j.ijfoodmicro.2026.111916

Interpretive Summary: Staphylococcus aureus is a common foodborne pathogen associated with meat and poultry products. Thermal processing is an effective approach to inactivate this pathogen in foods. Laboratory observations showed that heat inactivation of S. aureus in ground beef does not follow the typical first-order kinetics, but a nonlinear pattern. This study shows that one-step dynamic analysis can be used to more accurately determine thermal inactivation kinetic parameters. This method can be used to design more accurate thermal processing conditions to achieve food safety, while preventing overcooking and undercooking of final products.

Technical Abstract: This study was conducted to investigate the thermal resistance of Staphylococcus aureus in ground beef and develop kinetic models for designing effective thermal processes. A 3-strain cocktail of S. aureus was inoculated to irradiation-sterilized ground beef (10% fat) and subjected to both isothermal (55 - 65 ') and dynamic (0.3 - 1.8 '/min) heating to observe the bacterial survival. All isothermal survival curves were nonlinear, matching the characteristics of the Weibull model. The kinetic parameters of thermal inactivation were estimated using one-step kinetic analysis (OSKA) of isothermal survival curves and one-step dynamic analysis (OSDA) of both isothermal and dynamic survival curves. Depending on the methodology (OSKA or OSDA) used for inverse analysis, the exponent (shape parameter) of the Weibull model ranged from 0.5 to 0.6, suggesting the upward concavity of the survival curves. However, the results showed that the Weibull kinetic parameters from isothermal survival curves underestimated the bacterial inactivation under dynamic conditions, while the parameters estimated from the dynamic survival curves suggested that S. aureus became less heat-resistant under dynamic heating conditions. The kinetic parameters determined from dynamic survival curves by OSDA could more accurately predict the inactivation of S. aureus in ground beef (RMSE = 0.4 log CFU/g). This study affirmed the necessity to directly determine the thermal inactivation kinetics from dynamic conditions for developing more accurate thermal processes to prevent overcooking and undercooking.