Infrared and Microwave Drying of Rainbow Trout: Drying Kinetics and Modelling

Abstract

Rainbow trout (Oncorhynchus mykiss) fillets were subjected to microwave and infrared drying. For microwave drying, four different microwave power levels of 90, 180, 270 and 360 W were used, while for infrared drying, three different infrared power levels of 83, 104 and 125 W were used. A comparison of the drying kinetics showed microwave drying to be more effective for shortening the drying time that was required to reach a certain moisture content when compared with infrared drying. For determination of drying kinetics of fish, the experimental data for moisture content changes with time were evaluated using various empirical drying models while the effective diffusion coefficient was evaluated using Fick's law of diffusion. The activation energy values of fish samples dried by microwave drying were relatively higher than those for infrared drying. The logarithmic model was found to be the most suitable in describing the drying characteristics of rainbow trout fillets. Kinetic parameters for the color change were determined using Hunter L, a, b values and total color difference values. L and b values increased and a value decreased after drying. The Hunter color parameters changed more with infrared drying.