Multiscale modeling of transport mechanisms, strain, and stress in bananas during drying

Abstract

The two-scale Hybrid Mixture Theory-based mass balance and momentum balance equations, the multiscale energy balance equation, and the viscoelastic stress equation were solved to obtain the moisture, temperature, strain, and stress distributions during bananas’ convective drying. The model was validated against experimental average moisture contents (mean absolute errors (MAEs): 0.022–0.121 g/g solids), center and near-the-surface temperatures (MAEs: 0.6–7.7 °C), and volumetric strain (MAEs: 0.06–0.13). The model was then used to evaluate the effectiveness of the fan on/off strategy in reducing stress cracking compared to continuous drying. Simulation results of axial stress gradients and experimental results of global crack indices using a 5-point hedonic scale showed that the fan on/off strategy effectively reduced stress cracking compared to continuous drying. Thus, drying bananas at 60 °C by turning the fan on and off intermittently can be applied to reduce stress cracking in the product while requiring only 1.76% more energy compared to continuous drying.

Keywords:

• Drying
• stress
• strain
• stress-cracking
• multiscale modeling
• hybrid mixture theory

Disclosure statement

The authors report there are no competing interests to declare.

Additional information

Funding

This work was funded by the Center for Advanced Research in Drying (CARD) and the National Science Foundation (NSF) under the award number 1624812.