Abstract In this study, the banana drying process was investigated using three main mechanisms including convective heating, infrared radiation an‎d ultrasonic vibrations. Each of these mechanisms plays a specific role in heat an‎d moisture transfer. However, the application of ultrasonic vibrations can lead to better preservation of the quality of the final product by increasing the permeability of cell walls, reducing the resistance to moisture escape an‎d consequently reducing the drying time. The main objective of this study is to investigate the simultaneous effect of ultrasonic waves, convective hot air heating at 60°C an‎d infrared radiation on the banana drying process an‎d to eva‎luate the quality parameters of the dried product. Two types of heat sources including convective hot air an‎d infrared radiation were used for the experiments. Also, ultrasonic waves with a frequency of 20 kHz at four power levels including zero (without ultrasound application), 150, 300 an‎d 450 watts were considered as a variable factor. The drying process was carried out at a constant temperature of 60°C, which is considered the optimal temperature for drying bananas based on preliminary studies. In the infrared section, a 100-watt lamp was used to produce thermal radiation. In the convective hot air drying process, heat is transferred through the air flow an‎d mainly at the surface of the material, while in the infrared method, energy is applied locally an‎d more penetratingly, directly to the water molecules within the material, accelerating the evaporation process. The findings showed that increasing the ultrasonic power had a significant effect on reducing the drying time, improving the color an‎d preserving the texture of the fruit. For example, to reach 35% of the initial weight, the time required in the absence of ultrasonics an‎d with a power of 150 watts was 249 an‎d 232 minutes, respectively. While at power levels of 300 an‎d 450 watts, this time was reduced to 118 an‎d 109 minutes, respectively. Also, the examination of RGB histograms indicates that treatments combined with ultrasonic waves an‎d infrared radiation resulted in better preservation of the color an‎d texture quality of dried bananas compared to other treatments. The results of this study showed that the combined use of ultrasonic waves an‎d infrared radiation technologies has better performance compared to drying with hot convective air alone. The application of ultrasonic waves resulted in improved mass transfer efficiency, reduced process time, an‎d maintained the quality characteristics of the final product. Also, when the heat source is infrared radiation. The use of ultrasonic waves showed the greatest effectiveness in improving quality parameters; therefore, the use of methods such as ultrasonic drying can be suggested as an effective approach in optimizing the fruit drying process, especially on an industrial scale.

حامد رضوي بني

عليرضا مومني , بهمن اسدي