Hybrid mixture theory-based modeling of moisture transport coupled with quality changes in strawberries and carrots

Abstract

Hybrid mixture theory-based multiscale fluid transport equations were solved for drying of strawberries and carrots to predict the moisture transport during the process. The fluid transport equation was coupled with the selected product quality and nutritional attributes to predict changes in stress distribution, shrinkage, color parameters, and ascorbic acid/β-carotene content. The fluid transport equation includes a non-Fickian term that incorporates the effect of glass transition on moisture transport. A transformation between Eulerian and Lagrangian coordinates was used to include the moving volume effects due to shrinkage. Good agreements between the experimental and the predicted values of moisture content (RMSE ≤ 0.095, RMSE ≤ 0.579), color parameters (R² ≥ 0.958, R² ≥ 0.934), and volume changes (R² ≥ 0.871, R² ≥ 0.865) were obtained for strawberries and carrots, respectively. Drying in the vicinity of glass transition regime led to sharper moisture profiles, indicating non-Fickian transport. However, drying at temperatures higher than glass transition temperature of strawberries and carrots resulted in Fickian characteristics-round and smooth drying profiles for drying at 70 °C. Drying at higher temperature caused higher loss of quality attributes; it resulted in samples with lower color parameters and ascorbic acid or β-carotene content. Higher drying temperature resulted in greater shrinkage and deformation throughout the structure, leading to cracks and openings and faster degradation in quality attributes. The developed model would allow improving quality attributes and finding optimum processing conditions of strawberries and carrots.

Keywords:

• Drying
• strawberries
• carrots
• moisture transport
• non-Fickian

Disclosure statement

The authors declare that they have no conflicts of interest.

Additional information

Funding

The authors wish to thank NSF/IUCRC-Center for Advanced Research in Drying (CARD) and USDA-NIFA for providing partial financial support under the award numbers 1624812, and ILLU-698-308, respectively.