The smoke point, also referred to as the burning point, is the temperature at which an oil or fat begins to produce a continuous bluish smoke that becomes clearly visible, dependent upon specific and defined conditions. Smoke point values can vary greatly, depending on factors such as the volume of oil utilized, the size of the container, the presence of air currents, the type and source of light as well as the quality of the oil and its acidity content, otherwise known as free fatty acid (FFA) content. The more FFA an oil contains, the quicker it will break down and start smoking. The lower in FFA, the higher the smoke point.[dubious ] It is important to consider, however, that the FFA represents typically less than 1% of the total oil and consequently renders smoke point a poor indicator of the capacity of a fat or oil to withstand heat.
Smoke point decreases at different pace in different oils.
Considerably above the temperature of the smoke point is the flash point, the point at which the vapours from the oil can ignite in air, given an ignition source.
The following table presents smoke points of various fats and oils.
|Fat||Quality||Smoke point[caution 1]|
|Almond oil||221 °C||430 °F|
|Avocado oil||Refined||270 °C||520 °F|
|Mustard oil||250 °C||480 °F|
|Beef tallow||250 °C||480 °F|
|Butter||150 °C||302 °F|
|Butter||Clarified||250 °C||482 °F|
|Canola oil||220-230 °C||428-446 °F|
|Canola oil (Rapeseed)||Expeller press||190-232 °C||375-450 °F|
|Canola oil (Rapeseed)||Refined||204 °C||400 °F|
|Canola oil (Rapeseed)||Unrefined||107 °C||225 °F|
|Castor oil||Refined||200 °C||392 °F|
|Coconut oil||Refined, dry||232 °C||450 °F|
|Coconut oil||Unrefined, dry expeller pressed, virgin||177 °C||350 °F|
|Corn oil||230-238 °C||446-460 °F|
|Corn oil||Unrefined||178 °C||352 °F|
|Cottonseed oil||Refined, bleached, deodorized||220-230 °C||428-446 °F|
|Flaxseed oil||Unrefined||107 °C||225 °F|
|Lard||190 °C||374 °F|
|Olive oil||Refined||199-243 °C||390-470 °F|
|Olive oil||Virgin||210 °C||410 °F|
|Olive oil||Extra virgin, low acidity, high quality||207 °C||405 °F|
|Olive oil||Extra virgin||190 °C||374 °F|
|Olive oil||Extra virgin||160 °C||320 °F|
|Palm oil||Difractionated||235 °C||455 °F|
|Peanut oil||Refined||232 °C||450 °F|
|Peanut oil||227-229 °C||441-445 °F|
|Peanut oil||Unrefined||160 °C||320 °F|
|Pecan oil||243 °C||470 °F|
|Rice bran oil||Refined||232 °C||450 °F|
|Safflower oil||Unrefined||107 °C||225 °F|
|Safflower oil||Semirefined||160 °C||320 °F|
|Safflower oil||Refined||266 °C||510 °F|
|Sesame oil||Unrefined||177 °C||350 °F|
|Sesame oil||Semirefined||232 °C||450 °F|
|Soybean oil||234 °C||453 °F|
|Sunflower oil||Neutralized, dewaxed, bleached & deodorized||252-254 °C||486-489 °F|
|Sunflower oil||Semirefined||232 °C||450 °F|
|Sunflower oil||227 °C||441 °F|
|Sunflower oil||Unrefined, first cold-pressed, raw||107 °C||225 °F|
|Sunflower oil, high oleic||Refined||232 °C||450 °F|
|Sunflower oil, high oleic||Unrefined||160 °C||320 °F|
|Grape seed oil||216 °C||421 °F|
|Vegetable oil blend||Refined||220 °C||428 °F|
Hydrolysis and oxidation are the two primary degradation processes that occur in an oil during cooking. Oxidative stability is how resistant an oil is to reacting with oxygen, breaking down and potentially producing harmful compounds while exposed to continuous heat. Oxidative stability is the best predictor of how an oil behaves during cooking.
The Rancimat method is one of the most common methods for testing oxidative stability in oils. This determination entails speeding up the oxidation process in the oil (under heat and forced air), which enables its stability to be evaluated by monitoring volatile substances associated with rancidity. It is measured as "induction time" and recorded as total hours before the oil breaks down. Canola oil requires 7.5 hours, for example, whereas extra virgin olive oil (EVOO) and virgin coconut oil will last over a day at 110 °C of continuous heat. The differing stabilities correlate with lower levels of polyunsaturated fatty acids, which are more prone to oxidation. EVOO is high in monounsaturated fatty acids and antioxidants, conferring stability. Some plant cultivars have been bred to produce "high-oleic" oils with more monounsaturated oleic acid and less polyunsaturated linoleic acid for enhanced stability.
The oxidative stability does not directly correspond to the smoke point and thus the latter cannot be used as a reference for safe and healthy cooking.
Table 2-3 Smoke Points of Common Fats and Oils.