Canola seed damaged in storage by heating does a number of
things to degrade quality. Heating will burn off oil, so there is
less oil per ton of seed. Heating also changes the color of oil and
it increases free fatty acid content. For these reasons, processing plants tend to get very picky about how much they’ll take.
Processors can handle low levels of heated seed, but it still
adds cost. Heating will “set” the natural red color pigments in
canola. All canola oil contains some red pigments, which are
removed with the same clay process that removes the green
chlorophyll molecules. “Red color set in by heating is very dif-
ficult to remove,” Thiessen says. “Deodorizers can’t remove it,
and we end up with darker oil in the end.”
Heated canola also has higher levels of free fatty acids.
Fatty acids are usually in triglyceride bonds—three fatty acid
molecules are attached to a central glycerol molecule. Free
fatty acids are broken from the glycerol bond, and these “free”
fats greatly reduce the stability and shelf-life of oil.
Free fatty acids are found in all canola. Good quality new
canola seeds will have about 0.5% of fatty acids in the free
form. After a year in storage, oxidation through the aging process will push that up to around 1.0%. Heated canola will
have much higher free fatty levels as heat breaks the glycerol
bonds. Free fatty acids are removed with sodium hydroxide—
or “soda”—in the refining process. The sodium molecule in the
soda attaches to the fatty acid molecule to make “soapstock,”
which is removed from the oil in a centrifuge.
The optimum moisture content for canola entering a processing facility is between 7 and 7.5%. That is the target moisture
for ideal cooking and flaking results. (See step 2 in “The 11-step
process” on page 32.) Processing plants adjust canola moisture
up or down as needed before cooking.
“This delays product flow, which is an economic factor,”
Optimum moisture levels are also important to limit the
risks associated with seed spoilage and potential incubation of
harmful bacteria and mold. Artificially increasing moisture levels by adding water to the canola seed prior to delivery has the
potential to exacerbate these risks. Although this is an uncommon practice and illegal in the United States, it is important to
understand that adulterating the seed with water to increase
product weight not only increases costs associated with handling, it also poses a risk on the quality and safety of the downstream products.
Processing plants clean the seed prior to processing. Dockage
removed in cleaning the canola is typically added back to the
process after extraction. Scalpings, which are items screened
out of the seed that cannot be reincorporated into the meal,
are taken to the land fill.
CONTINUED ON PAGE 32