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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Microbial and Chemical Food Safety » Research » Publications at this Location » Publication #422489
Title: Effect of heating rate on thermal inactivation kinetics of Escherichia coli O157:H7 in ground beef

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

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2025
Publication Date: 3/10/2025
Citation: Ozturk, S., Huang, L., Sheen, S., Hwang, C. 2025. Effect of heating rate on thermal inactivation kinetics of Escherichia coli O157:H7 in ground beef. International Journal of Food Microbiology. 434. https://doi.org/10.1016/j.ijfoodmicro.2025.111152.
DOI: https://doi.org/10.1016/j.ijfoodmicro.2025.111152

Interpretive Summary: Thermal processing is an effective intervention method to ensure food safety. A thermal process is usually developed based on isothermal inactivation kinetics. However, the effect of heating rate on thermal resistance of microorganisms is not well understood and documented. This study investigated the effect of heating rate on thermal resistance of Escherichia O157:H7 in ground beef and discovered that slow heating significantly increased the bacterial thermal resistance. A more accurate unified kinetic model was developed to account for the increased thermal resistance using one-step dynamic analysis. The results from this study may be used by the food industry to design adequate thermal processes and to properly inactivate foodborne pathogens during dynamic heating.

Technical Abstract: The objective of this study was to investigate the effect of heating rate on thermal inactivation kinetics of microorganisms in food, testing the survival of Escherichia coli O157:H7 in ground beef under linear heating profiles and isothermal heating. A 4-strain cocktail of E. coli O157:H7 was inoculated to irradiation-sterilized ground beef (10% fat) and then subjected to isothermal heating (55 – 63°C) and linear heating (20 – 63°C). The kinetic parameters were determined from isothermal and dynamic survival curves using one-step analysis. Compared with isothermal heating, different degrees in the elevation of thermal resistance were observed in E. coli O157:H7 inoculated to ground beef during dynamic heating. For fast heating (1.2 – 1.8°C/min), the thermal resistance of E. coli O157:H7 was slightly increased in comparison to that exposed to isothermal heating. For slow heating (0.3 – 0.9°C/min), however, significantly increased thermal resistance was observed due to heat adaption at temperatures below 61.3°C due to heat adaptation, but E. coli O157:H7 became more sensitive to heat above this temperature, suggesting the increased resistance may diminish after reaching a critical temperature. To account for increased heat resistance, a unified kinetic model was developed and validated by applying one-step dynamic analysis to determine the kinetic parameters that can accurately describe the survival curves of all heating rates. This study demonstrated the necessity to consider the effect of heating rate, the use of dynamic heating to determine the thermal inactivation kinetic parameters, and the applicability of using one-step dynamic analysis for evaluating thermal processes. The results of this study may be particularly useful for designing slow-heating processes, such as sous vide cooking, to ensure proper cooking of products.