The Dominant Chemicals: Fatty Acid Composition
Canola oil is characterized by its favorable fatty acid profile, which is a major reason for its widespread use in cooking and food manufacturing. These fatty acids are primarily organized into triglycerides, the main component of the oil. The balance of monounsaturated, polyunsaturated, and saturated fats is a key feature of its chemical structure.
Monounsaturated Fatty Acids (MUFAs)
- Oleic Acid (Omega-9): Comprising approximately 60-65% of the oil, oleic acid is the most abundant fatty acid in canola oil. It is known for its role in potentially reducing LDL ('bad') cholesterol levels without affecting HDL ('good') cholesterol.
Polyunsaturated Fatty Acids (PUFAs)
- Linoleic Acid (Omega-6): Making up about 21% of the total fat, linoleic acid is an essential fatty acid that the body cannot produce on its own. It is important for brain function and overall growth.
- Alpha-Linolenic Acid (ALA) (Omega-3): Canola oil contains a notable percentage of ALA, typically around 9-11%. This plant-based omega-3 fatty acid is known for its anti-inflammatory effects and benefits to cardiovascular health.
Saturated Fatty Acids (SFAs)
Canola oil has one of the lowest saturated fat contents of any vegetable oil, at less than 7%. This low level contributes to its reputation as a heart-healthy choice when used as a replacement for high-saturated fat alternatives.
Minor but Important Compounds
Beyond the primary fatty acid content, canola oil also contains several other compounds that influence its nutritional value and stability.
- Tocopherols (Vitamin E): Canola oil is a rich source of Vitamin E, which functions as a potent antioxidant. The refining process, however, can reduce the concentration of these beneficial compounds.
- Phytosterols: These plant-derived compounds, such as beta-sitosterol and campesterol, are present in canola oil and are known to inhibit cholesterol absorption in the body.
- Polyphenols: Crude, unrefined canola oil contains polyphenols like canolol and sinapic acid, which have antioxidant and anti-inflammatory properties. However, the deodorization stage of conventional refining removes almost all of these compounds.
- Vitamin K: The oil provides a small but significant amount of Vitamin K, which is essential for proper blood clotting and bone health.
Chemicals Affected by Processing and Breeding
The very existence of modern canola oil is a story of chemical modification through plant breeding, aimed at removing historically harmful compounds from its ancestor, rapeseed oil.
The Erucic Acid Story
Original rapeseed oil contained dangerously high levels of erucic acid, a fatty acid linked to cardiac issues in animal studies. To create a safe, edible oil, Canadian scientists bred a new variety of the plant. This new variety, named 'canola' (short for 'Canadian oil, low acid'), is defined by having less than 2% erucic acid. Today's commercial canola oil typically contains less than 0.1% erucic acid, well below the established safety threshold.
Refining and Trace Chemicals
The vast majority of canola oil available for sale is a refined, bleached, and deodorized (RBD) product. The refining process involves multiple chemical treatments and high heat, which have specific chemical consequences.
- Hexane: A solvent, typically hexane, is used to extract the final amounts of oil from the seeds. While trace amounts of hexane can remain, extensive safety testing has found these levels to be far below any concentration that could cause health concerns.
- Trace Trans Fats: The high heat used during the deodorization step can cause a small percentage of the unsaturated fatty acids to convert to trans fats. However, commercial processors work to minimize this and the levels are extremely low, often below 1%.
- Loss of Antioxidants: As mentioned, refining removes many of the antioxidants and other minor compounds present in the crude oil. Cold-pressed, unrefined canola oil, on the other hand, retains more of these natural components but has a lower smoke point.
Comparison of Canola Oil to Other Common Oils
This table highlights the differences in the fatty acid composition of canola oil versus two other popular cooking oils, based on typical market values.
| Fatty Acid Type | Canola Oil | Olive Oil | Soybean Oil |
|---|---|---|---|
| Monounsaturated Fat (%) | ~63% | ~55-83% | ~23% |
| Polyunsaturated Fat (%) | ~28% | ~3.5-21% | ~58% |
| Saturated Fat (%) | ~7% | ~7.5-20% | ~16% |
| Omega-6:Omega-3 Ratio | ~2:1 | Varies | ~7.3:1 |
Conclusion
Canola oil's chemical composition is defined by its advantageous fatty acid profile, dominated by monounsaturated oleic acid and a balanced mix of essential polyunsaturated omega-3 and omega-6 fatty acids. This was achieved through specific plant breeding that dramatically reduced the problematic erucic acid content found in older rapeseed varieties. The commercial refining process, while removing some beneficial minor components like polyphenols and chlorophylls, ensures a stable, safe, and neutral oil for a variety of culinary applications. For consumers concerned with maximum nutrient retention, less refined options exist, though they are less suited for high-heat cooking. Ultimately, the chemicals in canola oil present a balanced and nutritionally valuable fat source that has been carefully developed for human consumption.
An excellent resource for learning about the history of canola and its development can be found on the Canola Council of Canada's website..
