Inactivation of Listeria innocua in ground meats by ohmic heating at different voltages
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Résumé en langage clair
The objective of this study was to determine the impact of ohmic heating (OH) treatments on a microbial contamination of ground meats by Listeria spp.. The OH system consisted of a Teflon cylinder cell, two Titanium electrodes, two fiber optic thermometers, a variable frequency AC power supply, a data logger and a PID controlling system. Pork and poultry meats (50 g) were contaminated with Listeria innocua ATCC 33090 at 5 log ufc/g. Treatments applied were a frequency of 10kHz and different voltages (10, 15 and 20V) to reach up 80oC internally. The microbial population in both meat types was impacted similarly by the treatments. There was no significant lost on the microbial population (0.24 log ufc/g) when the meat was exposed to OH for half of the time (50%) required to reach 80oC whereas a higher bacterial decrease was observed at 75% of the cooking time (2.42 log ufc/g). Treatments at 80oC (100%) showed a reduction ≥4.02 log ufc/g. For both meat types, the final microbial population was not function of the applied voltage. The Weibull model was used to fit the data and it provided an acceptable fit of the data for all conditions resulting in a model that could be used by the industry. Results indicated that OH could be a suitable alternative to process solid food products but further research is required to confirm the safety of the end product and to extend its application.
Résumé
The objective of this study was to determine the impact of ohmic heating (OH) treatments on a microbial contamination of ground meats by Listeria spp.. The OH system consisted of a Teflon cylinder cell, two Titanium electrodes, two fiber optic thermometers, a variable frequency AC power supply, a data logger and a PID controlling system. Pork and poultry meats (50 g) were contaminated with Listeria innocua ATCC 33090 at 5 log ufc/g. Treatments applied were a frequency of 10kHz and different voltages (10, 15 and 20V) to reach up 80oC internally. The microbial population in both meat types was impacted similarly by the treatments. There was no significant lost on the microbial population (0.24 log ufc/g) when the meat was exposed to OH for half of the time (50%) required to reach 80oC whereas a higher bacterial decrease was observed at 75% of the cooking time (2.42 log ufc/g). Treatments at 80oC (100%) showed a reduction ≥4.02 log ufc/g. For both meat types, the final microbial population was not function of the applied voltage. The Weibull model was used to fit the data and it provided an acceptable fit of the data for all conditions resulting in a model that could be used by the industry. Results indicated that OH could be a suitable alternative to process solid food products but further research is required to confirm the safety of the end product and to extend its application.