Shown is a two stage filtration system for treatment of fibrous vegetable matter, particularly oilseed materials such as oil-extracted canola flakes to separate the low valued fibrous material from soluble material and small non-structural water-insoluble material of higher value. The filtration system receives a vegetable matter slurry and passes the slurry through first stage filter which is an impeller type filter that operates to separate the slurry into a filtrate and a moist retentate. The moist retentate is further filter in a second compression filtration stage or a centrifuge to remove additional water. Small non-structural insoluble matter is removed in the filtrate.