Optimization of a Combined Heat Pump–Microwave Drying Process of Tilapia Fillets Using a Comprehensive Weighted Scoring Method

Tilapia fillets were dried with combined method of heat pump drying followed by microwave drying in heat pump drying temperature (30, 35 and 40°C), moisture content at the transition point of drying stages (30, 40 and 50%),and microwave drying power (119, 252 and 385 W). The regression model for the comprehensive weighted scores of the drying energy consumption and the product rehydration rate at various weights as a function of heat pump drying temperature, moisture content at the transition point of drying stages, and microwave drying power and its corresponding optimized process parameters were obtained. The analysis of process parameter data optimized at different weight levels of the drying energy consumption and the product rehydration rate indicates that, when the ratio of weight of the drying energy consumption over weight of the product rehydration rate increases, the optimized value of the heat pump drying temperature rises slightly but the rise is insignificant, whereas the optimized value of the moisture content at the transition point of the combined drying processes and that of microwave drying power increase.