|HONG, YOON-KI - Kangwon National University|
|YOON, WON BYONG - Kangwon National University|
|LIU, FANG - Washington State University|
|TANG, JUMING - Washington State University|
Submitted to: Journal of Food Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2016
Publication Date: 6/23/2016
Citation: Hong, Y., Huang, L., Yoon, W., Liu, F., Tang, J. 2016. Mathematical modeling and Monte Carlo simulation of thermal inactivation of non-proteolytic Clostridium botulinum spores during continuous microwave-assisted pasteurization. Journal of Food Engineering. 190(12):61-71. doi: 10.1016/j.foodeng.2016.06.012.
Interpretive Summary: Microwave-assisted pasteurization (MAP) is a novel technology currently under development for application in food processing. This technology combines microwave energy with hot water immersion to enhance heating, and is used for manufacturing higher quality refrigerated food products with extended shelf-life. This study uses computer simulation to analyze the effect of various processing parameters on thermal inactivation of non-proteolytic Clostridium botulinum spores in two products. The results of this study are used to guide the design development of MAP systems and processes for industrial applications.
Technical Abstract: The objective of this study is to develop a mathematical method to simulate the internal temperature history of products processed in a prototype microwave-assisted pasteurization system (MAPS) developed by Washington State University. Two products (10 oz. beef meatball trays and 16 oz. salmon fillet trays) are tested in this study. The aim of thermal processing is to inactive the spores of Clostridium botulinum Types B and E in beef meatball trays and Type E in salmon fillet trays. Analytical results show that a time-delayed exponential model can accurately describe the internal temperature histories of the products, with the root mean square error (RMSE) only 1.23 and 1.43, respectively, for beef meat ball and salmon fillet trays. The correlation coefficients (R2) between the simulated and measured temperature histories are > 0.995. Analytical results also show that the pre-heating section does not contribute to the total lethality. The majority of the lethality (63-70%) is accumulated in the microwave-assisted heating (MAH) section, while the remaining lethality is completed in the cooling section, suggesting that the cooling section can contribute a significant portion of the lethality and should be included in the calculation of the total lethality during thermal process development to avoid overheating. Monte Carlo simulation is 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, the simulation results show that more than 98.8% of the process 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 show that the MAH section is critical to the accumulation of lethality in the products, 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. In addition, the simulation results also show that the variations in the cooling water temperature do not significant alter the total lethality, suggesting that it may not be necessary to precisely control the cooling water temperature, which may simplify the design of the system and reduce the operational costs. The results of this study may be used to improve the design and operation of the MAPS.