Theoretical and experimental analysis of the drying kinetics of okra using infrared dryer

Abstract

AbstractIn this research, the thin‐layer drying characteristics and quality parameters of okra pods were investigated by subjecting it to drying using an infrared drier. The drying process was achieved at three different radiation intensities of 0.167, 0.235, and 0.520 W/cm2 and included three air velocities of 0.3, 0.5, and 0.7 m/s. A detailed analysis of their drying kinetics (drying curve, drying rate curve, effective moisture diffusivity, and mathematical modeling), shrinkage and rehydration, and total color change were performed. Results showed the drying process occurred in the falling‐rate period. The drying time was reduced with rising infrared intensity and declining air velocity. The Midilli et al. model provided the best fitting for each drying curve (coefficient of determination (R2) > 0.99, reduced chi‐square (χ2), and root mean square error [RMSE] closer to zero). The effective moisture diffusivity values among various drying conditions ranged from 2.89 to 12.23 × 10−10 m2/s, which were within the normally predictable range for food materials. The rehydration ratio increased as air velocity increased and decreased as infrared radiation intensity increased. The phenomenon of shrinkage ratio had a positive relationship with higher levels of infrared radiation and a negative association with faster airflow. As the air velocity and radiation intensity rose, there was an observed increase in the overall color difference between fresh and dried okra. The current study's results will provide additional insights into the optimal drying conditions for preparing okra as a snack, breakfast item, or other culinary applications.Practical applicationsOkra is important commodity in terms of global agricultural production. As okra is a perishable product with a short shelf life, the food industry has been forced to find methods, such as drying, that extend its storage life by months. The conventional system of hot air dying displays many disadvantages. Infrared drying intended a substitute way to improve the quality of dehydrated products. However, infrared is rarely expended alone as a drying method and is frequently combined with other drying systems. The main goal of this work is to study an innovative process to extend the storage life of okra reducing energy and time consumption and ensuring sample quality.