The applicability of Weibull model for the kinetics inactivation of Listeria monocytogenes and Escherichia coli O157: H7 on soybean sprouts submitted to chemical sanitizers in combination with ultrasound at mild temperatures

This research was performed to evaluate the inactivation kinetics of slightly acidic electrolyzed water (SAEW), fumaric acid (FA) and their combination simultaneous with ultrasound (US) at a mild temperature against L.monocytogenes and E.coli O157:H7 on sprouts. The effects of combined treatments on sensory quality of sprouts were also examined. A t4D equal to 10 min was needed for the combined SAEW with FA (SAEW + FA) at 40 °C to reach 4 log reduction of L.monocytogenes; while the same combination simultaneous with ultrasound (SAEW + FA + US) provided the t4D value of 12; 7 and 3 min for L.monocytogenes at 23°, 30° and 40 °C respectively. For E.coli O157:H7, only (SAEW + FA + US) gave the t4D of 14; 9 and 3 min at 23°, 30°, and 40 °C respectively. The Weibull model provided a good fit with R2 ≥ 0.9 for both bacteria and the root mean square errors (RMSEs) were in the range of 0.01-0.48 for L.monocytogenes and 0.02-0.54 for E.coli O157:H7. The samples submitted to both combined treatments remained in good quality at the end of storage with slight deterioration due to ultrasound usage. This study suggests that the Weibull model could successfully be used to determine exact contact time for inactivating foodborne pathogens on food.