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Evaluation of non-isothermal inactivation on survivals of pathogenic bacteria by predictive models
- Yoon, Jae-Hyun, Han, Areum, Paek, Jeongyeup, Lee, Sun-Young
- Lebensmittel-Wissenschaft + [i.e. und] Technologie 2019 v.101 pp. 366-373
- Cronobacter sakazakii, Escherichia coli O157, Listeria monocytogenes, Salmonella Typhimurium, Weibull statistics, bacteria, detection limit, equations, glucose, heat tolerance, models, prediction, virulent strains
- This study was conducted to examine thermal resistances of Escherichia coli O157:H7, Cronobacter sakazakii, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes upon exposure to non-isothermal inactivation at various heating rates (HRs) between 1.0 °C and 9.0 °C/min. Bacterial cultures were re-suspended in tryptic soy broth without dextrose and treated with non-isothermal inactivation processing (to maximally 60 °C) at different HRs. Predictive models were used to determine fundamental kinetic parameters that describe characteristic behaviors of these bacteria under dynamic environments. At a HR of 9.0 °C/min, viable numbers of these organisms declined below the detection limits (<1.0 log CFU/ml). In contrast, E. coli O157:H7, C. sakazakii, and S. Typhimurium survived at levels of <2.5 log CFU/ml at HRs of 1.5–6.0 °C/min. Under non-isothermal processing, the thermal tolerances increased with slow HRs. Lag time (LT) and δ from the modified Gompertz and the Weibull survival functions were significantly (p < 0.05) higher at the lower HRs. The Weibull distribution showed reliable goodness-of-fits ranging from 0.889 to 0.999, indicating that this equation model was shown to be effective in predicting survival kinetics of these bacteria under non-isothermal inactivation conditions at different HRs. In conclusion, slow HRs resulted in higher thermal tolerances of these bacteria under non-isothermal processing.