Dissertation
Optimization of Microwave Assisted Thermal Sterilization and pasteurization processes using analytical models and computer simulation
Washington State University
Doctor of Philosophy (PhD), Washington State University
2022
DOI:
https://doi.org/10.7273/000005061
Abstract
The busier lifestyle of the population has led to increasing market demand for Ready-To-Eat (RTE) meals. For this reason, Microwave Assisted Thermal Sterilization (MATS) and Pasteurization Systems (MAPS) were developed at Washington State University for the commercial production of chilled and shelf-stable RTE meals. For process development using these technologies, it is desirable to have an effective production tool that predicts the heating of a product as affected by food composition, package size and microwave power setting. Understanding the influence of those contributing factors is critical to ensure safe and quality food production. Thus this research aimed at: (i) developing engineering charts for process development based on the MAPS; (ii) developing engineering charts for process development based on the MATS; (iii) analyzing the dielectric properties of purified and tap circulating waters used in both systems for assessing energy delivery to the food package; and (iv) to validate the effect of using purified circulating water to improve energy efficiency in the MATS. The governing Maxwell's and heat transfer equations, numerical simulation tools, Finite-Difference Time-Domain (FDTD) method, MATLAB and QuickWave software were used in the research. The developed charts accurately predicted dielectric properties, optimal preheating temperature, optimal salt content, heating temperature and time. The validation experiment with the pilot-scale MAPS and MATS systems showed that the measured heating rates at the cold spots of the food samples in the microwave heating sections were positively correlated with predicted heating rates from the chart (R2 > 0.95). Furthermore, the experimental heating pattern results agreed with the predicted optimal salt contents for mashed potatoes, peas, and rice samples. Analytical and computer simulation results confirm the advantage of purified circulating water over tap water. In purified water, 4 – 7% of the 915 MHz microwave power was lost, compared to 11 – 20% loss in tap water; the electric field intensity and power dissipation within food were higher by 45 – 57% and 19 – 32%, respectively, compared to tap water. In experimental validation, purified circulating water reduces the use of microwave power by 35.8% compared to tap water. Finally, this research demonstrated the application of engineering charts for process schedule development and the advantage of purified circulation water to improve heating and energy efficiency.
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Details
- Title
- Optimization of Microwave Assisted Thermal Sterilization and pasteurization processes using analytical models and computer simulation
- Creators
- Yonas Gezahegn
- Contributors
- Juming Tang (Advisor)Patrick D Pedrow (Committee Member)Shyam S Sablani (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Biological Systems Engineering
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 258
- Identifiers
- 99901019940101842
- Language
- English
- Resource Type
- Dissertation