Microwave Assisted Convective Drying Characteristics of Elephant Foot Yam

F. M. Sahu, Parth Pandit

Elephant Foot Yam was blanched at 80°C for 4 min in hot water and exposed to microwave treatment under different microwave power ranging from  300 W to 900 W and exposure time (1, 1.5 and 2 min) and then dried in convective dryer at 60°C to study their effect on microwave assisted convective drying characteristics. Drying time, average drying rate, effective moisture diffusivity, activation energy and rehydration ratio were various factors studied. Increased in microwave power and exposure time increased drying rate and decreased the drying time. The whole drying took place in falling rate period only. Midilli et al. model was found to describe the drying behaviour of elephant foot yam most precisely (highest R² = 0.9996; least RMSE = 0.0051). The effective moisture diffusivity values ranges from 4.2 × 10^-10 to 1.1× 10^-9 m²/s and activation energy from 3.14 to 4.48 W/g. From storage study and sensory evaluation with quality in terms of protein, total sugar, ash and oxalate content was found to be acceptable in all drying treatments. Based on oxalate content and drying characteristics, exposure of 900 W microwaves for 2 min followed by hot air drying at 60°C was found to be most acceptable.