Unrefined olive oil has a lower smoke point than refined cooking oils.
In cooking, it is extremely important to select the best oil. Cooking an oil above the smoke point can result in a bad taste and burning. Oil is said to reach this point when it starts to smoke, and many oils have a flash point very close to the same temperature, which means the oil can potentially catch fire. This is usually not a desired effect when cooking, so most cooks maintain a library of oils to allow selection of the best oil for the kitchen job.
Avocado oil is an unrefined oil.
When the oil reaches the smoke point, it starts to degrade. It will taste bad, adding an acrid smell and flavor to the food. The smoke forms substances that can be carcinogenic and probably shouldn’t be breathed or consumed. In addition to having a bad taste and being potentially dangerous, oil that has reached this temperature is not suitable for cooking because it can burn food.
Coconut oil can be purchased refined or unrefined, although refined is best for cooking over high heat.
Cooks need to select an oil based on the type of cooking job. In general, unrefined oils that are cold-harvested have a lower smoking point than other oils. Unrefined oils include olive oil, avocado oil, and many nut oils. They tend to taste better and are excellent for sautéing, roasting and seasoning. This type of oil should be used if the cooking vessel does not exceed 176°C (350°F) and should be selected based on the flavor it will impart to the food.
Refined oils are extracted by heat and are therefore better able to withstand high temperatures, with a smoke point that is often double that of unrefined oils. In theory, any unrefined oil can also be made refined. Refined oils tend to be less flavorful and will also be transparent and free of sediment. They should be used for cooking over high heat, including stir-fries.
Peanut oil, which has a high smoke rate.
If the oil in a pan starts to smoke, the pan should be removed from the heat and allowed to cool. Overheated oil should be discarded and replaced with one with greater heat tolerance. Cooks should be aware that some refined oil blends have a lower heat tolerance, while the best refined oils for high heat cooking are peanuts, canola, safflower and soybeans. Many cooks prefer peanut oil because it has a lighter feel when used in deep frying applications. Most oils will perform better if they are heated gradually, rather than thrown into a very hot pan. If heated and cooled slowly, some oils can be reused, although they should be discarded if they begin to discolor or smell rancid.