Impact of radio frequency-assisted hot air drying on drying kinetics behaviors and quality features of orange peel

Abstract

The aims of the study were to dry orange peel (OP) by radio frequency-assisted hot air drying (RF-HAD) and conventional hot air drying (HAD), and to investigate the drying efficiency of the drying methods and quality parameters of dried waste. Various electrode gaps (60, 70, and 80 mm) and sample thicknesses (10, 30, and 50 mm) were studied to investigate the effect of RF-HAD on drying characteristics of OP. RF-HAD method showed a shorter drying time (about 74% decrease in the drying time) than HAD method. The electrode gap of 70 mm and the sample thickness of 30 mm were determined as the best conditions of RF-HAD due to providing shorter drying time and better sample quality. Moreover, the samples dried by RF-HAD method had better quality properties (color values, total polyphenol content, total carotene content, ascorbic acid content, antioxidant activity, water retention capacity, flow behavior) than those dried by HAD method. Therefore, outputs of this effective drying technique in terms of time and quality are essential to recover the valuable components from OP.