“High dockage means extra work for the pre-cleaning step,
and it can add extra handling costs if dockage exceeds the
amount that can be added to meal,” Ghabour says.
Canola processing is an important and necessary step in
producing the end products our customers want. The extra
costs to process lower grade canola exhibit precisely why
Canada has grading standards and why striving for quality
has its economic rewards.
Jay Whetter is the editor of Canola Digest magazine, a joint
publication of the Alberta Canola Producers Commission, Sask-Canola, the Manitoba Canola Growers Association and the
Canola Council of Canada. This article originally ran in Canola
Digest and is reprinted with permission.
Canola meal leaves the processing facility in pellet form for easy handling.
Canola goes through 11 major steps as it moves through a
processing facility to be made into refined customer-ready oil
and meal pellets.
1. Seed is delivered by truck either by individual producers or
grain companies. The truck is inspected and sampled, then
graded according to Canadian Grain Commission Standards
to determine the value to the vender along with the current price for the grower. Seed is segregated as to the type
and/or grade and stored until used by the processing plant.
Modern processing plants usually just have a week or two
of storage capacity.
2. Seed is cooked and then flaked by roller mills to ensure all
oil is exposed to as much surface area as possible. Optimum flake thickness is 0.3–0.38 mm. Flakes thinner than
0.2 mm are very fragile while flakes thicker than 0.4 mm
result in lower oil yield.
3. A mechanical screw-type expeller squeezes about
two-thirds of the oil from the flakes.
4. After expelling, the high-oil expeller cake (meal plus
remaining oil) goes through solvent (hexane) extraction
to separate the remaining oil. The cake moves through
a long wash chamber as hexane is poured over top,
dissolving the oil from the meal.
5. Meal is then heated to remove the hexane, which is
condensed and used again. Meal is then ground and/
or pelleted for sale into the feed market.
6. Oil removed from cake in step 4 is desolventized by heating it under vacuum. Hexane becomes a gas at 60–65°C,
so it boils off at a much lower temperature than the oil,
making for easy separation. This gas is vacuumed from
the heating chamber and condensed back into a liquid
7. Oil removed from expellers in step 2 has the solids
removed by filters or centrifuges and is combined with oil
from the extraction process in step 6.
8. The combined oil then goes for refining. Step one in
refining combines oil with sodium hydroxide—“soda”—to
react with water soluble components. This removes gums
and free fatty acids to create a product called soapstock,
which is a high energy feed ingredient. Soapstock is
separated from the oil with a centrifuge.
9. Oil is then clarified using a clay that adsorbs any pigments
remaining in the canola oil. Oil is filtered to remove the
10. The final refining step is deodorization. Oil is heated to
240°C under almost perfect vacuum to distill off short
chain molecules, such as any remaining free fatty acids,
along with flavor and odor compounds. The final product
is mild tasting, light colored canola oil.
11. This oil is then weighed and shipped in rail cars, truck
tanks or smaller containers to a packaging facility where it