Drying kinetics of common agricultural products under different processing factors and methods

Michael Onwuka, B.E.

Master's thesis

Abstract:

This study investigated the effect of infrared (IR) drying on sliced Golden Delicious apples, focusing on drying kinetics, color changes, and quality parameters. The influence of drying temperature (40, 50, and 60°C) was evaluated. The research shows that drying rates increased significantly with higher temperatures, reflecting faster moisture removal. Three mathematical models were meticulously chosen and our result identified the logarithmic and Weibull distribution models as the most effective in representing the drying curves within the investigated temperature range. The Weibull model exhibited the most consistent performance across temperatures. The goodness-of-fit of each model was assessed using 4 major statistical measures: root mean square error (RMSE), chi-square (χ2), coefficient of determination (R2), and modelling efficiency (EF). Lower RMSE and χ2 values alongside higher R2 and EF values indicate a better fit between the model and the experimental data. Higher drying temperatures within the studied range (40-60°C) correlated with better color preservation, potentially due to advantages of IR drying technology. The browning index (BI) and total color change (ΔE) increased with temperature, while the whiteness index (WI) decreased. Rehydration capacity, a measure of water uptake ability peaked at a moderate temperature (50°C), suggesting its importance for process optimization. Shrinkage values showed complex interactions with the drying temperature.

Keywords

Agricultural products, Drying behaviour, Color measurements, Shrinkage, Specific energy consumption

Language used: English

Date on which the thesis was submitted / produced: 2. 4. 2024

Thesis defence

• Date of defence: 20. 5. 2024
• Supervisor: doc. Ing. Abraham Kabutey, Ph.D.
• Reader: Cimen Demirel, externi

Czech University of Life Sciences Prague

Faculty of Engineering

Master programme:
Technology and Environmental Engineering