Abstract
We built a prototype rectangular-waveguide microwave applicator to heat rapeseed in a continuous process for the pre-treatment of rapeseed for oil expression in a press. The short-circuit plate of the waveguide was moved back and forth by a quarter of the guide wavelength at a frequency of 0.5 Hz to form an oscillating electric field in the applicator. While the plate was being moved, the rapeseed was irradiated. This method could heat rapeseed up to 115 ± 4 ℃ continuously at a throughput of 35 kg/h. In the following oil expression test, with a choke opening of 7.5 mm, the oil recovery rate increased from 22.6 % without heating to 28.4 %. The acid value and oxidative stability of the oil showed no major changes, and the content of chlorophyll tended to be higher. These results show that the technique is effective as a pre-treatment for oil expression with a small-scale press.
