Cyclical variation of drying air temperature on Mytilus galloprovincialis convective drying

Abstract

Cyclic drying has been reported as an innovative drying technique for the drying of food materials in terms of drying time, energy cost and product quality. In this study, drying characteristics and product quality of continuous and cyclic drying of Mytilus galloprovincialis in a convective solar dryer were investigated. A two-stage increasing–decreasing drying air temperature (sinusoidal pattern) of the solar dryer was used to obtain the desired cyclical variation of the drying temperature while keeping other drying air parameters constants. The advantages of employing cyclic heating on the drying kinetics, energy consumption are demonstrated. Analytical results illustrated an effective drying time of mussels by a reduction of 1.5% and optimum energy consumption does not exceed 23 kWh of drying process by applying cyclic drying technique compared to continuous drying of air temperature. Furthermore, According to the proximate composition of AOAC method and following Total viable count (TPC) of the dried mussels, it was observed that cyclic air temperature allows to yield higher retention of protein, glycogen, reduce significantly the effect of stresses compared to the constant conditions of drying, and it is possible the reduce the overall color change as well as an accepted texture. Several empirical and semi-empirical models were used to fitting drying curves of experimental data. It was found that the Page model seems to be most suitable to describe the drying curves of Mytilus galloprovincialis. The second law of Fick’s was used to determine the effective moisture diffusivity at different conditions of drying. As results, the values of effective diffusivity obtained by applying cyclic drying were in the margin with the drying at constant conditions that was reached 2.84 × 10−9 m2/s.