87-8 |
Kinetic analysis of nonlinear thermal inactivation of microorganisms |
L. HUANG, USDA-ARS-Eastern Regional Research Center, 600 E. Mermaid Ln., Wyndmoor, PA 19038-8598 Although the first-order thermal inactivation kinetics of microorganisms has been successfully used in the food industry for more than a century, sufficient evidence exits that not all the thermal inactivation curves are linear. According to the literature, approximately 2/3 of the thermal inactivation curves possess different degrees of nonlinearity. Therefore, thermal process calculation based on the first-order kinetics for nonlinear inactivation behaviors may not be accurate. The objective of this research was to develop and validate a new kinetic model that is capable of describing both linear and nonlinear (concave and convex) thermal inactivation curves. The hypothetic kinetic model was modified from the traditional first-order thermal inactivation kinetics, and was validated using E. coli O157:H7 in ground beef and L. monocytogenes in beef, pork, and chicken. Results indicated that the new model can be used to describe both the linear and nonlinear thermal inactivation behavior of microorganisms, and is particularly suitable for describing both concave ( E. coli ) and convex ( L. monocytogenes ) curves. Since the model can provide a better description of the nonlinear (convex and concave) thermal inactivation behavior of microorganisms, it can be used to design thermal processes with higher accuracy and thus substantially reduce overcooking or undercooking when the target microorganism exhibits nonlinear thermal inactivation behavior.
Session 87, Food Microbiology: General
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