Mathematical modeling of shrinkage deformation in eggplant undergoing simultaneous heat and mass transfer during convection-oven roasting

• A theoretical description of shrinkage in a visco-elastic material was provided.
• Shrinkage velocity is equal to water lost during roasting of eggplant.
• Directional analysis shows more shrinkage in thickness than in the radial direction.
• Estimation of internal evaporation improves the simulated results.
• Interactions between transport phenomena and shrinkage were successfully modeled.

This study aimed to analyze experimentally and by modeling the shrinkage deformation of Japanese eggplant (Solanum melongena) during roasting by simultaneous heat and moisture transport model coupled with a structural mechanics model applicable to a body undergoing volumetric changes, as a consequence of moisture removal. Cylindrical slices (45 mm × 10 mm) were roasted for up to 15 min. Roasting experiments were performed using a convection-oven at 250 °C. Several coefficients and parameters required for calculations were experimentally obtained. An implicit finite element method was applied using a FORTRAN program. In this study, an approximately equal reduction rate in moisture content losses and volume shrinkage was observed (R2 ≥ 0.99). The volumetric (Sv) and directional shrinkage were successfully estimated by developed empirical equations (e.g. R2 > 0.98 for Sv). The simulation of temperature and moisture distribution undergoing shrinkage deformation confirmed the importance of internal evaporation in the transport model.