Influence of Infrared Heating Parameters on the Drying Characteristics of Onion Slices

The overall performance of the onion was statistically evaluated based on slice variables such as thickness, infrared power, and air velocity. Drying time, color, shrinkage, water activity, and rehydration ratio are critical parameters in the analysis of material properties. The onion slices were subjected to drying under the ensuing settings: infrared powers of 0.13, 0.22, and 0.34W/cm², air velocities of 0.5, 1.0, and 1.5m/s, and slice thicknesses of 2, 4, and 6 mm. The experimentally acquired dehydrating curves were subjected to a curve-fitting process to align them with the thin-layer drying equations. The findings indicated that the drying time increased with air velocity and slice thickness but decreased with increasing infrared power. The mean activation energy was determined to be 19.02-29.83kJ/mol under various conditions. While the shrinkage ratio increased and declined with air velocity, the rehydration ratio grew and dropped with increasing infrared radiation intensity and air velocity. The increased infrared and reduced air velocity improve water disappearance from the exteriors of the onion. The color change is accompanied by increased airflow and IR.