Effectivenes of a microwave fluidised bed dryer in eradication of seed-borne botrytis grey mold of lentil

Abstract

[EN] A single mode microwave cavity, with a 2.45 GHz microwave source, was modified to have a microwave fluidized bed and its potential to eliminate Botrytis grey mold (BGM) pathogen of lentil seeds was evaluated. Air speed was maintained at a constant value and was just enough to fluidize 100g of red lentil seeds in the sample holder. Two wet-based (w.b.) seed moisture contents (MC) of 10.5% and 18.5% were prepared and the process parameters were selected as air temperature at 50 and 60°C; microwave power at 0, 300, 400 W for 18.5% MC and 0, 400, 500 W for 10.5% MC; and exposure times of 5 and 10 min. The effect of the process parameters on seed moisture loss, seed germination, the electrical conductivity of seed soaking water and the percentage of infected seeds (IS%) were analyzed. The most effective factors on moisture loss, after seed moisture content, was exposure time, followed by microwave power and air temperature. While the final bed temperature was mostly affected by air temperature, and then by microwave power. Furthermore, based on general full factorial regression and Pareto chart of standardized effects, moisture content had a major influence on the reduction of IS%. Seed pathogen inoculum reduction, without significant seed viability loss, was obtained by applying microwave power of 300W and set air temperature of 60°C (actual inlet air temperature of 57±1°C) on seeds with MC of 18.5% for 10 min. This gave a 27% reduction in IS%, from 82% to 55%. Thus, these results showed that applying microwave fluidized bed dryer was able to reduce BGM pathogen in lentil seeds and it could be considered as part of integrated disease management