Dielectric properties and microwave and infrared‐microwave combination drying characteristics of banana and kiwifruit

Abstract

AbstractThe scope of this study was to investigate the effects of initial moisture content, different drying methods and different microwave power on quality and dielectric properties of banana (Musa cavendishii) and kiwifruit (Actinidia deliciosa) and it was also aimed to examine the correlation between dielectric properties and microwave and microwave‐infrared combination (MW‐IR) drying characteristics of banana and kiwifruit. Samples with different initial moisture contents were dried by using different microwave powers (180 W, 270 W, 360 W for banana) and (350 W, 420 W, 490 W for kiwifruit). For combination drying of banana, the application parameters were adjusted as 360 W for microwave power and 600 W for upper and lower halogen lamps (600 W) and for kiwifruit those were adjusted as 420 W and 600 W, respectively. The drying characteristics investigated throughout the study were moisture content and color values (L*, a*, and b*). Dielectric properties of fresh and processed samples were also detected. It was observed that an increase in microwave power resulted in an increase in rate of drying and a decrease in processing time. It was also found that combining infrared with microwaves resulted in higher rates of moisture loss from the product. Dielectric properties of banana and kiwifruit samples decreased with increasing microwave power and initial moisture content. When microwave and combination dried samples were compared with conventionally dried ones, products with lower final moisture content and higher quality could be produced with a time saving of approximately 98%.Practical applicationsConventional drying like hot‐air drying takes a long time even at high temperatures which results in a decrement of the dried product quality. To overcome such a problem, as well as to obtain a product with better nutritional and sensory properties, the process could be speeded up by the application of microwave energy. In this study, both microwave and microwave‐infrared combination drying were investigated. The most important property of combination drying is the ability to combine the time saving advantages of microwave with surface moisture removal advantage of infrared heating. There is a lack of knowledge of literature about an appropriate drying method to preserve the best quality of banana and kiwifruit samples, thus in this study the basic scope is developing an efficient, time‐saving drying method to improve quality characteristics of banana and kiwifruit samples.