Purpose: The objective of this study was to evaluate the thermal lethality of products (10 oz. beef meatball trays and 16 oz. salmon fillet trays) processed in a microwave-assisted pasteurization system (MAPS).
Methods: Thermal processing parameters were selected to inactivate the spores of C. botulinum Types B and E in beef meatball trays and Type E in salmon filet trays. After a mathematical method was developed to accurately simulate the internal temperature of products, Monte Carlo simulation was used to analyze the lethalities delivered at different processing steps of the pasteurization process.
Results: The simulation results showed that the majority of the lethality (63 - 70%) was accumulated in the microwave-assisted heating (MAH) section, while the remaining lethality was completed in the cooling section, suggesting that the cooling section can contribute a significant portion of the lethality. Monte Carlo simulation was also used to analyze the effect of different processing parameters on the total lethality of products. With a target lethality of 6 log-reductions in the spores, more than 98.8% of the processes will achieve a minimum of a 5-log reduction of the spores of C. botulinum Type B in 10 oz. beef meatball trays, and more 98.5% of the processes achieve > 5 log-reductions in the spores of C. botulinum Type E in 16 oz. salmon fillet trays. The results of sensitivity analysis showed that the MAH section is critical to the accumulation of lethality in the products, with the heating temperature being the most sensitive parameter influencing the total lethality, followed by the heating rate and time in this section and the temperature in the pre-heating section.
Significance: The results of this study may be used to improve the design and operation of the MAPS.