Yes, most canola oil sold in grocery stores is heavily processed. The standard bottle of canola oil has gone through at least six distinct industrial steps: cleaning, cooking, pressing, solvent extraction, refining, and deodorizing. Each step uses heat, chemicals, or both to transform raw canola seeds into the pale, neutral-tasting oil you’re familiar with. Less processed versions exist, but they’re the exception, not the norm.
How Standard Canola Oil Is Made
The process starts with canola seeds being cleaned, then cooked and flaked to break open the cell walls. These cooked flakes pass through screw presses (called expellers) that squeeze out most of the oil through sheer mechanical force. What’s left behind is a compressed cake that still contains a meaningful amount of oil.
To get that remaining oil out, manufacturers saturate the presscake with a petroleum-derived solvent called hexane. The hexane percolates through the cake and dissolves nearly all the leftover oil. The solvent is then evaporated off and recaptured for reuse. European regulations cap hexane residues in finished oil at 1 mg/kg, though the U.S. FDA does not specify a maximum residue limit for edible oils.
What Happens During Refining
Crude canola oil, whether pressed or solvent-extracted, is dark, strongly flavored, and contains compounds that shorten shelf life. The refining process strips all of that away in stages.
First comes degumming, where small amounts of phosphoric or citric acid are mixed into the oil to pull out phospholipids and other gummy compounds. Next, the oil is treated with caustic soda (sodium hydroxide), which reacts with free fatty acids and converts them into a soap-like byproduct that gets washed away. Then the oil passes through bleaching clays, activated carbon, or special silica to absorb pigments and remaining impurities. The goal is a pale yellow, visually “clean” oil that consumers associate with freshness.
The final and most aggressive step is deodorization. The oil is heated to temperatures between 200°C and 235°C (up to 455°F) under vacuum for an extended period. This strips out volatile compounds responsible for off-flavors and odors, along with contaminants like pesticide residues. The result is an oil with almost no taste or smell, which is exactly what food manufacturers want for cooking and processed foods.
What Processing Changes in the Oil
Canola oil’s basic fatty acid profile survives refining largely intact. Finished oil typically contains around 60 to 65% oleic acid (a monounsaturated fat), 17 to 21% omega-6 linoleic acid, and 9 to 10% omega-3 linolenic acid. That ratio is one of the reasons canola oil gets recommended as a heart-healthy option.
But some things do change. The high temperatures during deodorization convert a small portion of the oil’s unsaturated fats into trans fats. Refined canola oil contains roughly 1.9 to 3.6% trans fatty acids, with the omega-3 component being especially vulnerable to this transformation. These aren’t the same as the industrially produced trans fats in partially hydrogenated oils (which have been largely banned), but they are a byproduct of processing that wouldn’t be present in unrefined oil.
Refining also strips out about 25% of the oil’s tocopherols, which are natural forms of vitamin E that act as antioxidants. To compensate for this lost stability, some manufacturers add synthetic antioxidants like TBHQ, BHA, or BHT to the finished product. Check the ingredient label if this matters to you.
Cold-Pressed and Expeller-Pressed Alternatives
Not all canola oil goes through solvent extraction and chemical refining. Two alternatives skip parts of the process.
- Expeller-pressed canola oil uses a second round of mechanical pressing instead of hexane to extract remaining oil from the seed cake. No chemical solvents are involved, though heat is still generated by the friction of pressing, and the oil may still go through some refining steps.
- Cold-pressed canola oil is the least processed option. Seeds are not heated before, during, or after pressing, with extraction temperatures staying below about 50°C (122°F). The oil is extracted through mechanical force alone, with no solvents, no chemical refining, and no high-temperature deodorization.
Cold-pressed canola oil retains more of its natural color, flavor, and antioxidant content. It also retains compounds like chlorophyll that would be stripped during refining. The tradeoff is a shorter shelf life, a stronger taste, and a lower smoke point. Refined canola oil has a smoke point around 204°C (400°F), making it a popular choice for frying, while cold-pressed versions vary more and tend to be better suited for dressings and low-heat cooking.
How to Tell What You’re Buying
If a bottle of canola oil doesn’t say “cold-pressed” or “expeller-pressed” on the label, it was almost certainly made using hexane extraction and full chemical refining. That’s the industry default. The vast majority of canola oil on supermarket shelves falls into this category.
Cold-pressed and expeller-pressed versions are typically found in natural food stores or specialty sections and cost significantly more. They’ll also look different: darker in color, with a noticeable seed flavor rather than the bland neutrality of refined oil. If you’re specifically trying to avoid solvent-extracted, chemically refined oil, those label terms are what to look for.