Drying 2004 – Proceedings of the 14th International Drying Symposium (IDS 2004) São Paulo, Brazil, 22-25 August 2004, vol. C, pp. 1599-1603 1599 MICROWAVE-ASSISTED AIR DRYING OF CASSAVA SLICES Ana M Andrés; Noelia Betoret, N.; Bernardet Guillermo and Pedro Fito Food Technology Department. Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain e-mail: aandres@tal.upv.es. Keywords: osmotic dehydration, microwaves, cassava ABSTRACT Microwave-assisted hot-air dehydration of cassava slices was performed under different drying conditions. The objective of the investigation was to compare hot air drying and microwave-assisted hot-air drying and to analyze the influence of the osmotic dehydration prior to drying. Osmotic pre-treated samples were obtained by submerging the cassava slices in a 20% -salt solution (w/w) for 60 minutes at 30ºC. The microwave output power and the air temperature were the variables in the experiments. An important reduction in the drying time was observed when applying microwaves, mainly for samples osmotically pre-treated as a consequence of the influence of salt ions in the dielectric properties of the material. INTRODUCTION Cassava is one of the main tubercles cultivated in the tropical and subtropical zones of Africa, Asia and Latin America, regions where high temperatures and highrelative moisture predominate. The most popular names used to identify this plant are: yuca, manihot, mandioca and cassava. Cassava belongs to the Euphorbiaceae family, and the genus Manihot has about 200 species, with, Manihot Esculenta Crantz being the most important in commercial scale. (Lopes et al., 1995). The high water activity of fresh cassava, demands the application of some method of preservation necessary for its storage . A technological operation that can be applied is the dehydration. Drying is a technique of conservation that consists on the elimination of large amount of water present in a food by application of heat under controlled conditions, with the objective to diminish the chemical , enzymatic and microbiological activities, that are responsible for the deterioration of foods (Fellows, 1988). Sun drying and air drying are some of the traditional methods used for food dehydration, but recent studies pointed out the efficiency in water removal when air drying is combined with microwaves heating