Effects of ethyl oleate and microwave blanching on drying kinetics of bitter gourd.

In the present study effects of pre-treatments such as blanching with hot water and microwave, ethyl oleate dipping, and combinations of these treatments on drying characteristics of the bitter gourd (Momordica charantia L.) at various temperature were studied. The overall drying time was reduced significantly in the ethyl oleate treated and microwave blanched samples. The minimum diffusivity (2.65 × 10-8 m2/s) was observed in control samples whereas the maximum diffusivity (3.86 × 10-8 m2/s) was observed in ethyl oleate treated and microwave blanched samples at 50 °C. Ethyl oleate treated and microwave blanched samples dried at lowest temperature (50 °C) showed the lowermost shrinkage ratio (46.04%). The rehydration ratio increased from 3.49 to 4.90 as the temperature increased from 50 to 70 °C for control samples. Combined pre-treatment of ethyl oleate and microwave blanching had resulted in most acceptable drying characteristics and quality of bitter gourd. Drying of the samples were mathematically modelled. The drying characteristics of bitter gourd could be explained suitably by Page drying model.