A mathematical model for predicting the transport process and quality changes during intermittent microwave convective drying

Nghia Duc Pham; M I H Khan; M A Karim

doi:10.1016/j.foodchem.2020.126932

A mathematical model for predicting the transport process and quality changes during intermittent microwave convective drying

Food Chem. 2020 Apr 27:325:126932. doi: 10.1016/j.foodchem.2020.126932. Online ahead of print.

Authors

Nghia Duc Pham¹, M I H Khan², M A Karim³

Affiliations

¹ Science & Engineering Faculty, Queensland University of Technology, 2 George St, Brisbane, QLD 4000, Australia; Engineering Department, Vietnam National University of Agriculture, Viet Nam.
² Science & Engineering Faculty, Queensland University of Technology, 2 George St, Brisbane, QLD 4000, Australia; Department of Mechanical Engineering, Dhaka University of Engineering & Technology, Gazipur 1700, Bangladesh.
³ Science & Engineering Faculty, Queensland University of Technology, 2 George St, Brisbane, QLD 4000, Australia. Electronic address: azharul.karim@qut.edu.au.

PMID: 32387989
DOI: 10.1016/j.foodchem.2020.126932

Abstract

Intermittent microwave convective drying (IMCD) is an advanced drying method where volumetric heating of samples drives the drying process. Understanding of the physical effects of IMCD on simultaneous heating and mass transfer as well as quality changes during IMCD is essential to predict accurately drying processes and quality attributes of end products. However, there is a lack of studies in this particular interest area. The aim of this research was to develop an IMCD model coupled with quality degradation kinetics by integrating a simultaneous heat and mass transfer model with Maxwell's equations for microwave heating and the chemical reaction kinetics model. The simulated results were compared with experimental results and a good agreement was observed. As it was found that power ratio (PR) had a vital role in altering quality attributes, different PR and drying conditions were considered to investigate the effects of IMCD on the drying kinetics. The simulated results showed that the model was capable of predicting accurately moisture and temperature distributions along with heath beneficial compounds, such as total phenolic content (TPC) and ascorbic acid (AA) as well as colour changes during IMCD processing. About 70% of AA was degraded during IMCD drying using PR of 1/3. However, losses were reduced when PR was reduced to 1/4 or 1/5. Likewise, TPC degraded significantly during the early stages (first 60 min) of IMCD processing but stabilised at later stages.

Keywords: 3D mathematical model; Ascorbic acid; Heat and mass transfer; IMCD; Total phenolic content.