Energy and exergy analysis, drying kinetics, modeling and quality parameters of microwave-dried turmeric slices

Abstract

The aim of this study was to evaluate the effect of curing and microwave power levels on energy analysis, drying characteristics, modeling and quality parameters of turmeric slices in microwave dryer. Drying experiments were carried out for fresh and cured turmeric slices. Four microwave power levels of 30%, 50%, 80% and 100% with the total output power of 900 W were used for this study. From the drying rate curve, it was observed that the drying process mainly takes place in the warming up and falling rate periods. Among the eight models evaluated in the study, Midilli et al. and Page model had a good agreement with the experimental data. Moisture diffusivity values increased (1.83 × 10−08 to 1.59 × 10−07 m2/s) as the microwave power level increases. From the energy analysis, it was found that specific moisture extraction rate and specific energy consumption values varied in the range of 0.146–0.395 kg/kWh and 9.1093–24.6093 MJ/kg, respectively. Energy efficiency values (9.24–24.75%) were found to be higher than the exergy efficiency values (2.18–12.77%). Quality parameters such as color value and curcumin content of the fresh samples were found to be higher when compared to cured samples. SEM analysis revealed the porous internal structure of the dried samples. From this study, it is revealed that curing of turmeric slices has negligible effect on the parameters analyzed. A moderate microwave power level would be suitable for turmeric drying to produce high-quality product with lesser energy consumption.