Techno-economic, environmental impact and exergy analysis of microwave assisted drying of nutmeg mace

This study aimed to reduce the drying time of mace under microwave pre-treatment and to analyze the energy, exergy, and techno-economic feasibility of the process. Effect of microwave pretreatments were studied under three microwave power levels of 160, 320, and 480 W for an exposure time of 60 s. Drying time during convective drying without microwave pretreatment was 5.5 h, which was decreased by 18.2%, 27.3%, and 36.4% at microwave powers of 160, 320, and 480 W respectively. Moisture content of mace decreased from 45.66 ± 1.14% to 6%. under various drying conditions. The two-term exponential model fitted the drying data under optimized conditions. The drying efficiency and exergy efficiency of the microwave assisted drying of mace was observed to be 29.53% and 26.74%, respectively. The values of economic attributes indicated the benefit cost ratio of 1.9 and payback period of 2.1 years. The sustainability index and environment destruction coefficient of the system was determined to be 1.10 and 2.41, respectively. Waste energy ratio, environmental impact factor and improvement potential of the developed drying process was 0.72, 1.52, and 0.46, respectively. The study concluded that microwave at optimal power of 320 W can be utilized for commercial production of mace with better retention of essential oil, oleoresin and color.