Microwave pre-treatment of canola seeds and flaked seeds for increased hot expeller oil yield.

Abstract

Microwave (MW) pre-treatment of canola seeds or flaked seeds was found to be a superior alternative to the conventional thermal pre-treatment (steam). Flaked seeds were "cooked" (heat-treated) with steam or using microwave treatments in the temperature range of 62-130°C prior to expeller pressing. Microwave cooking at 100°C resulted in the highest increase in the pressed oil yield, which is an increase of 3.7% (w/w) on a pressed oil basis or 9.0% (oil in seed basis) compared with steam cooking. Whole canola seeds conditioning was conducted with microwaves or steam, in the temperature range of 40-75°C, followed by microwave or steam cooking at 100°C to evaluate the effect of MW treatment during conditioning on the expeller oil yield. The use of a continuous microwave process for combined conditioning of whole seeds at 55°C and subsequent cooking of flaked seeds at 100°C resulted in a 4.0% increase in expeller oil yield, compared with steam conditioningand cooking. The influence of dry basis (db %) moisture contents of 5%, 11.5%, and 16.5% on oil yield after steam or MW treatments of seeds and flaked seeds was also studied. The moisture content of 11.5% (db %) yielded the highest net oil yield for both MW and steam at best conditioning and cooking temperatures of 55°C and 100°C, respectively. No significant impact of MW cooking was seen on oil quality compared with conventional steam cooking.