Superheated steam sterilization of foodborne pathogens on pork belly: Biphasic kinetics, dual-action mechanisms, and logistic model validation.

Abstract

This study pioneered an integrated investigation of superheated steam (SHS) sterilization by quantifying kinetics and unraveling dual-action mechanisms against foodborne pathogens (Salmonella Typhimurium, Listeria monocytogenes and Staphylococcus aureus) on pork belly surfaces. Sterilization kinetics of SHS with different treatment temperature (160-200 °C) and flow rates (20-30 kg h-1) during 60 s were modeled using Weibull and Logistic equations. Comparatively, the Logistic equation was rigorously validated as superior (R2 ≥ 0.998, RMSE ≤ 0.097, Af ≤ 1.183), enabling precise prediction of microbial inactivation dynamics. Kinetic analysis revealed a novel biphasic pattern: rapid pathogen reduction (≤20 s) followed by a distinct tailing phase (20-60 s), challenging conventional single-phase sterilization assumptions. Mechanistically, SHS induced immediate disruption of cell wall/membrane integrity, evidenced by a decline from 2.07 to 2.25 to 0.52-0.75 King units·(100 mL)-1 in AKP activity, an increase from 2.88 to 2.98 to 3.93-4.18 mS cm-1 in conductivity, and concurrent surges in nucleic acid/protein leakage within 20 s. Critically, ATPase activity plummeted 68-77 %, from 3.46 to 3.53 to 0.8-1.1 U·mg prot-1, directly linking membrane destabilization to energy metabolism collapse. These findings established SHS as a multi-modal intervention, synergizing thermal inactivation with targeted biochemical disruption of microbial homeostasis (cellular ion balance disruption, material exchange, and ATPase activity interference). By providing mechanistic insights and predictive modeling tools, this research validated SHS as a scalable, eco-friendly alternative to chemical sanitizers, reducing antimicrobial resistance risks and environmental footprint in meat processing.