Evaluation of infrared drying for okra: Mathematical modelling, moisture diffusivity, energy activity and quality attributes

Abstract

Okra (Hibiscus esculentus L.) was dried using an infrared drier at radiation intensities of 0.167, 0.235, and 0.520 W/cm2 and air velocities of 0.3, 0.5, and 0.7 m/s to determine its thin-layer drying characteristics and quality parameters. Okra dried during falling rates, and drying time was reduced with rising infrared intensity and declining air velocity. Eleven alternative numerical simulations fit the data gathered through the drying kinetics. The equation developed by Midilli et al. was determined to be the most useful model for illuminating okra's drying behavior. Fick's diffusion model was used to derive effective moisture diffusion coefficients (Deff), which ranged from 2.89 to 12.23 ×10−10 m2/s for the drying conditions. The rehydration ratio improved with increasing air velocity and reduced with higher infrared radiation intensity. In contrast, the shrinkage ratio increased with raised infrared radiation intensity and reduced with higher air velocity. The overall color difference between fresh and dried okra increased as air velocity and radiation intensity increased.

Keywords

• Infrared
• Drying kinetics
• Quality
• Okra