Comparative Analysis of Dehydration Methods for Apple Fruit

Abstract

Fruit dehydration is a key option for food preservation, in order to increase shelf life and promote exportation. Numerous methods of dehydration have been developed in recent decades. The aim of the present work is to perform an assessment of the dehydration methods used more frequently with apple fruit, and subsequently, compare them as to the conditions of operation (temperature, speed of drying and drying time) and energy aspects (energy requirement and energetic efficiency). The comparative analysis shows that drying with microwave associated with a second method of drying has greater benefits in terms of quality of the final product. In addition, using the two methods it is possible to overcome the limitations of each one used individually. The microwave drying and microwave drying combined with vacuum present the lowest drying times, 0.87-h and 0.28-h, respectively, as opposed to traditional techniques (sun drying and solar drying). In terms of energy efficiency, it was found that among the methods analysed the higher rates were observed for the fluidized bed dryer (28.0-64.0%), microwave drying (79.0%) and drying by infrared radiation (30.0-60.0%). The infrared drying method appears to be the most efficient, presenting lower costs and providing greater benefits in terms of drying times, energy efficiency and, organoleptic and nutritional characteristics of the final product.