A novel infrared drying technique for processing of apple slices: Drying characteristics and quality attributes

Most conventional drying methods often result in significant degradation of food items' flavor, color, and bioactive compounds due to the drying process. One of the effective drying methods for improving food quality and reducing the drying process's duration is applying heat through infrared radiation. Infrared-dried apple slice quality was evaluated experimentally and statistically in terms of the drying period, rehydration ratio, colour, and shrinkage as a function of infrared intensity levels, slice thicknesses, and air velocity. Apple slices were dried at infrared intensities of 0.130, 0.225, and 0.341 W/cm2, air velocities of 1.0, 0.5, and 1.5 m/s, and slice thicknesses of 6, 4, and 2 mm. Throughout the procedure, the dried slices were reduced from an initial moisture content of 87.5 %-11 % (w.b.). According to the findings, the drying time needed to decrease the moisture level of sliced apples to roughly 0.12 g water/g dry matter ranged from 200 to 280 min, 170-240 min, and 130-190 min at infrared radiation intensities of 0.130, 0.225, and 0.341 W/cm2, respectively. Water activity values for dried apple slices ranged from 0.371 to 0.450. The rehydration ratio increased with increasing air velocity and reduced with increased infrared radiation intensity. In contrast, the shrinkage ratio increased with increased infrared radiation intensity and decreased with increased air velocity. Slices of fresh and dry apples had a more significant overall colour difference as radiation intensity and air velocity increased.