Experimental Evaluation of Hot Air-Assisted Continuous Microwave Drying of Oyster Mushroom (Pleurotus ostreatus)

Abstract

This study evaluated the efficiency of hot air−assisted continuous microwave (HACM) drying for oyster mushrooms (Pleurotus ostreatus), focusing on drying kinetics, quality attributes, and economic feasibility. Response surface methodology was used to optimize drying parameters viz., microwave power (600–1000 W), air temperature (40°C–60°C), and airflow rate (0.5–1.5 m/s), to minimize drying time and water activity while maximizing rehydration ratio. Optimal conditions obtained were air temperature, microwave power, and air flow rate of 55.05°C, 1000 W, 0.81 m/s, respectively, with a drying time of 5 h, water activity of 0.532, and rehydration ratio of 2.49. The dried mushrooms showed 29.63% shrinkage, a total color change of 28.51, pore sizes of 2.06–15.70 µm, and a sensory acceptability score of 8.1. Proximate analysis indicated enhanced protein (33.21%) and carbohydrate (47.34%) contents. The HACM system achieved energy efficiency and specific energy consumption of 23.12% and 2.71 kWh/kg, respectively. The benefit-cost ratio of 1.55 and a payback period of 2.56 years confirmed the economic viability of the system and its potential for scalable and high-quality mushroom preservation.