A mathematical model from literature was adapted to predict the pressure profile and oil yield for canola in a lab-scale extruder. Changing the description of the expression process from filtration to consolidation significantly improved the performance and physical meaning of the model. The model predicts the trends in pressure and residual oil content with varying screw rotational speed and choke opening very well, but the residual oils content is always overestimated. The model was unable to describe the influence of temperature on pressure and residual oil content. With the developed model, four extruder designs were compared based on the resulting residual oil contents at the same process conditions. Conventional extrusion followed by a gas assisted mechanical extraction stage was found to result in the lowest residual oil content (14.5 wt%) compared to single-stage conventional residual oil content of 19 wt%.
- Gas assisted mechanical expression