How does expeller-pressed canola oil differ from regular canola oil, and is it worth the added expense?
To understand expeller pressing, it helps to first understand the standard extraction process for canola oil. Manufacturers typically use a chemical called hexane to extract oil from a hybrid version of rapeseed, then remove the chemical with further processing, refine the oil, and bleach it to lighten its color and reduce odors. Expeller pressing, on the other hand, involves a mechanical screw-type press that uses friction and pressure to squeeze the oil out of the seeds. While it isn’t as efficient as standard extraction (hence its higher price), the oil undergoes fewer chemical changes. The result, some manufacturers claim, is more natural flavor and less damage to the oil’s nutrients.
To see if we could tell these types of oil apart, we bought a bottle of Spectrum’s organic expeller-pressed canola oil ($9.99 for 32 ounces) and Wesson canola oil ($3.50 for the same quantity) and used the oils to make stir-fried beef and simple lemon vinaigrette. Both oils produced equally well-browned crusts in the beef with no difference in taste. The expeller-pressed vinaigrette was cloudier than the vinaigrette made with regular canola oil, but again, tasters found they had exactly the same flavor.
Our advice: If you are buying for taste alone, it’s not worth spending more for expeller-pressed canola. But if you want to avoid chemical processing, expeller-pressed oil is worth the extra cost.