Microwave fluidised bed drying of red lentil seeds: Drying kinetics and reduction of botrytis grey mold pathogen

Abstract

Botrytis grey mould (BGM) is a problematic seed-borne disease of lentil crop, with little known about its possible physical control. Microwave fluidized bed dryers have been widely studied for grain, fruit and vegetable drying. In the present study, simultaneous drying and disinfection of red lentil seeds, were investigated in a microwave fluidized bed at 4 microwave powers of 0, 300, 400 and 500W using fluidizing hot air at 50 and 60°C. Moisture diffusivities of lentil seeds were defined by considering the Fick's second law of diffusion in one direction in a sphere with convective boundary conditions as well as negligible external resistance to mass transfer. They varied from 0.44×10−10 for hot air alone at 50°C to 3.06×10−10m2/s for microwave power and air temperature combinations of 500W and 60°C by considering convective boundary condition for the seeds. Drying times obtained from well-fitted Page's model were applied for drying of the seeds contaminated with BGM. The results indicated that infected seeds percentage (IS%) could be reduced by 30% by applying combinations of microwave power and hot air at 300W and 60°C or 400W and 50°C, without a significant loss of seed viability. Thus, microwave fluidized bed drying has a good potential to reduce seed born BGM in lentil crop.