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One of the most contentious issues in using olive oil for cooking is its smoke point.

When frying the oil in the pan is heated between 160-240°C. The optimal temperature is around 180°C .Lower temperatures are used in other forms of cooking – roasting, baking etc. In Asian countries where the wok is used for stir frying, temperatures higher than this can be expected.

The importance of smoke point from a chef’s point of view was brought home to me by a chef in Blenheim, New Zealand when I quizzed him about which oil he used for frying. His answer was avocado oil because of its high smoke point, and secondly he liked the flavour. Pursued as to why he didn’t use some of the locally produced extra virgin olive oil, his answer was that he was so busy in the kitchen that he could not watch the frying all the time and the lower smoke point of olive oil often caught him out with the food he was frying being spoilt. Price was not an issue.

There is also a perception that ‘burned’ frying oil has deteriorated producing toxic and, in some cases, cancer inducing substances. Some of the deterioration products formed in fats and oils heated to high temperatures for prolonged periods are peroxides, aldehydes, ketones and and hydroperoxides. Any of these can have toxic effects. Some are volatile – aldehydes and ketones – so do not get into the food, others are not absorbed by the intestine, but some are.

The bluish smoke given off at the smoke point is the aldehyde acrolein, a result of the breakdown of the glycerol associated with triglycerides. The smoke point marks the beginning of nutritional and flavour degradation and the production of the free radicals which play an important role in causing diseases. The presence of anti-oxidants help prevent this and increase the smoke point.

 

Fat

Quality

Smoke Point

Almond oil

 

420°F

216°C

Avocado oil

 

520°F

271°C

Butter

 

350°F

177°C

Canola oil

Expeller Press

464°F

240°C

Canola oil

High Oleic

475°F

246°C

Canola oil

Refined

470°F

240°C

Coconut oil

Unrefined

350°F

177°C

Coconut oil

Refined

450°F

232°C

Corn oil

Unrefined

320°F

160°C

Corn oil

Refined

450°F

232°C

Cottonseed oil

 

420°F

216°C

Flax seed oil

Unrefined

225°F

107°C

Ghee (Indian Clarified Butter)

 

485°F

252°C

Grapeseed oil

 

420°F

216°C

Hazelnut oil

 

430°F

221°C

Hemp oil

 

330°F

165°C

Lard

 

370°F

182°C

Macadamia oil

 

413°F

210°C

Olive oil

Extra virgin

375°F

191°C

Olive oil

Virgin

420°F

216°C

Olive oil

Pomace

460°F

238°C

Olive oil

Extra light

468°F

242°C

Olive oil, high quality (low acidity)

Extra virgin

405°F

207°C

Palm oil

Difractionated

455°F

235°C[1]

Peanut oil

Unrefined

320°F

160°C

Peanut oil

Refined

450°F

232°C

Rice bran oil

 

490°F

254°C

Safflower oil

Unrefined

225°F

107°C

Safflower oil

Semirefined

320°F

160°C

Safflower oil

Refined

510°F

266°C

Sesame oil

Unrefined

350°F

177°C

Sesame oil

Semirefined

450°F

232°C

Soybean oil

Unrefined

320°F

160°C

Soybean oil

Semirefined

350°F

177°C

Soybean oil

Refined

450°F

232°C

Sunflower oil

Unrefined

225°F

107°C

Sunflower oil

Semirefined

450°F

232°C

Sunflower oil, high oleic

Unrefined

320°F

160°C

Sunflower oil

Refined

450°F

232°C

Tea seed oil

 

485°F

252°C

Vegetable shortening

 

360°F

182°C

Walnut oil

Unrefined

320°F

160°C

Walnut oil

Semirefined

400°F

204°C

Comparison of smoke point of a range of vegetable oils used in cooking. The comparative list of smoke points given above is from Wikipedia. Other sources confirm that within a few degrees these figures are generally accepted. 

You will note that refining oils tends to increase the smoke point as impurities and free fatty acids are removed. Hence refined ‘extra light’ olive oil has a higher smoke point than extra virgin olive oil. The table shows that high quality extra virgin olive oil has a higher smoke point than refined – due to the presence of anti-oxidants and low free fatty acid levels. Another selling point for high quality extra virgin olive oils.

Another point to consider is that when frying very little oil penetrates the food and so even if smoke point is exceeded, the toxins formed are unlikely to enter into the component that is eaten in any quantity. Drying the food after frying to remove the external oil also reduces toxin intake.

This penetration of the food is related to the viscosity of the oil. ‘Fluid’ oils such as soy, peanut and sunflower oil give a light fried food because of the small amount of oil penetration, on the downside there are health issues because of the high low level of unsaturation. But chefs are less concerned with health than presenting a palatable and good looking dish.

Olive oil is a good cooking medium given the smoke point, health and penetration issues. 

As far as the loss of health attributes provided by the anti-oxidants in extra virgin olive is concerned, tocopherols are destroyed or inactivated at 180°C while phenols are more resistant to heat and will be retained at higher temperatures.

In summary on smoke point, with frying at the ideal temperature around 180°C high quality extra virgin olive oil is fine, and there are the added health attributes.

Another issue with chefs and frying with extra virgin olive oils is the aroma, which can be quite strong especially with oils from varieties such as picual. This can be overcome by the use of oils from varieties which have less strong aromatic profiles or the use of later harvested oils. However, as always there is a compromise, later harvested oils will have lower anti-oxidant levels and possible higher free fatty acid and peroxide value.