Microwave Drying of Corn (Zea mays L. ssp.) for the Seed Industry

Abstract

Microwave drying of corn (Zea mays L. ssp.) was conducted in this study and its germination was tested after drying. The objective of the test was to determine an optimum microwave drying method for corn seeds to achieve maximum germination and minimum drying time, as well as to obtain the maximum temperature that can achieve the best results without reducing the viability. The different methods used for drying included constant temperature drying at 30, 40, and 50°C; intermittent power microwave drying; and fixed power microwave drying at 2, 3, 3.5, and 4 W/g. The drying was started with an initial moisture content of 33% (wb) and ended with a final moisture content of 16% (wb). In the constant temperature method, the microwave power was automatically controlled to keep the temperature constant throughout the drying period. A control cycle of 20 s was used for intermittent drying in which the microwave generator was on for 12 s and off for 8 s throughout the drying process. In fixed power microwave drying, the power was constant throughout the process. The germination tests were conducted on all samples with the rolled blotting paper method. The minimum drying time was reached with 4 W/g fixed power where 0% germination resulted. The optimum method for drying of corn seeds for maintaining a high germination rate was 4 W/g intermittent power microwave drying, which took 110 min to dry from 33% moisture content to 16% (wb). The germination percentage of 4 W/g intermittent power was 93.3%. The maximum permissible temperature of corn seeds when subjected to intermittent microwave power resulting in maximum germination was 67°C.

Keywords:

• Constant temperature
• Corn
• Fixed power
• Intermittent power
• Microwave drying

ACKNOWLEDGMENT

The authors are grateful to the Natural Sciences and Engineering Research Council of Canada and Le Fonds Québécois de la Recherche sur la Nature et les Technologies for financial assistance for this study.