Multiphysics modeling of microwave processing for enzyme inactivation in fruit juices
Résumé
Microwave processing of fruit juice model solution containerized in a cylinder was evaluated by a numerical multiphysics model, aiming to understand the temperature and peroxidase inactivation profiles along processing. In order to rigorously simulate the microwave processing, a finite element model was developed by iteratively coupling electromagnetism, heat transfer, fluid flow and enzyme inactivation. Peroxidase inactivation was determined experimentally, presenting a first-order kinetic behavior (°D C 70 = 234.377 ± 7.068 s, z = 12.072 ± 0.295°C, R 2 = 0.97), which was implemented in the simulation. Enzyme inactivation could be well predicted, considering convection currents and spatial temperature distribution within the sample during microwave heating. Experimental results under various combinations of time and temperature were used to validate the results from simulation. Good agreement was obtained in terms of both temperature at the sample center (R 2 ≥ 0.99) and peroxidase inactivation (R 2 = 0.97). Therefore, the presented results highlight the relevance of a coupled modeling for predicting enzyme inactivation, taking into account the potential presence of cold spots during microwave heating, allowing further process optimization.
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