Most canola oil sold in grocery stores is highly processed. It goes through a multi-stage industrial procedure involving chemical solvents, high heat, bleaching, and deodorizing before it reaches the bottle. This process, known in the industry as RBD (Refined, Bleached, and Deodorized), is standard for nearly all conventional vegetable oils, not just canola.
How Canola Oil Is Made
Canola oil starts as tiny seeds from the canola plant, a variety of rapeseed bred to contain very low levels of erucic acid (capped at no more than 2% of fatty acids under FDA standards). Turning those seeds into the clear, neutral oil you see on shelves requires several industrial steps.
First, the seeds are crushed and mechanically pressed to extract some of the oil. But pressing alone doesn’t get all of it out, so the remaining seed meal is mixed with hexane, a petroleum-derived solvent that dissolves the leftover oil. The hexane-oil mixture is then heated and distilled to evaporate the hexane, which is collected and reused. After extraction, the crude oil still contains compounds that affect its color, taste, and shelf life, so it moves through three more stages: refining (removing gums, free fatty acids, and other impurities), bleaching with clay to strip out pigments, and deodorizing with high-temperature steam to remove volatile compounds that give the oil an unpleasant smell or flavor.
The result is a nearly colorless, odorless oil with a neutral taste and a smoke point around 400°F (204°C), which makes it versatile for cooking. But the journey from seed to bottle involves significant chemical and thermal manipulation.
What Happens to the Oil During Processing
Each stage of refining changes the oil’s composition in measurable ways. The deodorization step is the most consequential. It uses temperatures high enough to alter the structure of some fatty acids. Research published in Chemical Engineering and Processing found that the initial trans fat content in crude canola oil (0.1 to 0.3%) can rise to as high as 5% in the refined product, entirely due to deodorization. This is a different source of trans fats than partial hydrogenation, the process used to make margarine, but the chemical result is similar.
Canola oil is often promoted for its omega-3 content, specifically a plant-based omega-3 called alpha-linolenic acid. But processing takes a toll here too. Heating bleached canola oil at 220°C for ten hours reduces that omega-3 content by nearly 20%, according to data cited by Harvard’s T.H. Chan School of Public Health. Standard commercial processing doesn’t necessarily heat oil for that long, but the finding illustrates how sensitive these fatty acids are to the temperatures involved.
Some refined canola oils also contain synthetic antioxidants added to extend shelf life. Common ones include TBHQ, BHA, and BHT. These are FDA-approved food additives, but their presence is another layer of processing that separates the final product from anything you’d find in nature.
Hexane Residues in the Final Product
One of the most common concerns about solvent-extracted oils is whether hexane remains in the finished product. The short answer: trace amounts typically do, but they’re extremely small. A study testing commercial vegetable oils found hexane residues in canola oil at levels up to 42.6 micrograms per kilogram. That’s roughly 0.04 parts per million, well below the European Union’s maximum residue limit of 1 milligram per kilogram (1 ppm). None of the samples tested exceeded that safety threshold.
Whether those trace amounts matter over a lifetime of daily use is a question without a definitive answer, but the levels are far below what regulators consider harmful.
Where Canola Oil Fits on the Processing Spectrum
The NOVA food classification system, widely used in nutrition research, sorts all foods into four groups based on how much industrial processing they’ve undergone. Refined canola oil falls into Group 2: processed culinary ingredients. This puts it in the same category as white sugar, butter, and table salt. It’s not classified as “ultra-processed” (Group 4) because it’s used as a cooking ingredient rather than being a ready-to-eat product loaded with additives like emulsifiers, flavorings, and modified starches.
That said, NOVA’s categories describe how a food is used, not just how it’s made. The extraction process for canola oil is undeniably industrial. The distinction matters because some people equate “processed” with “unhealthy,” while NOVA treats processing as a spectrum. Canola oil is processed, but it’s not in the same category as a packaged snack cake.
Less Processed Alternatives
If the processing itself concerns you, expeller-pressed canola oil offers a middle ground. Instead of using hexane, expeller pressing relies entirely on physical pressure to squeeze oil from the seeds. No solvents are involved, which eliminates the possibility of hexane residues entirely. The friction and pressure during pressing generate temperatures between 140 and 210°F, significantly lower than what occurs during conventional deodorization.
The tradeoff is practical. Expeller pressing extracts less oil from each batch of seeds, which makes it less efficient and more expensive. Cold-pressed canola oil takes this a step further by controlling temperatures even more tightly, but both versions still undergo some degree of refining to be shelf-stable. Unrefined expeller-pressed canola oil has a smoke point ranging from 375 to 450°F, which is comparable to refined versions, so cooking performance isn’t dramatically different.
You’ll typically find expeller-pressed canola oil in natural food stores or labeled as such on the bottle. If the label simply says “canola oil” with no further description, it was almost certainly made through conventional solvent extraction and full RBD processing.
The Bigger Picture
Canola oil is not unique in being highly processed. Soybean oil, corn oil, sunflower oil, and most other neutral cooking oils go through the same RBD procedure with the same solvents and temperatures. The only common cooking oils that skip this process entirely are those that can be extracted through simple pressing alone, like extra virgin olive oil or virgin coconut oil, where the oil content of the source material is high enough that mechanical pressure does the job.
Whether the level of processing in canola oil is a dealbreaker depends on what you prioritize. The finished product is low in saturated fat, has a useful smoke point, and contains some omega-3s, though less than the crude oil started with. It also contains trace solvent residues, industrially generated trans fats, and potentially synthetic antioxidants. For people who want to minimize industrial processing in their diet, expeller-pressed canola oil or less-processed oils like extra virgin olive oil are straightforward swaps.