Researchers at the University of the Basque Country in Spain studied olive, sunflower and flaxseed oils for their aldehyde content after slowly heating all the oils to 190℃. The conclusion once again debunked the myth that frying with Olive Oil is unsafe.
It is believed that frying food in vegetable oil can be unhealthy because of the toxic chemicals (called aldehydes) created in the process. Aldehydes are organic compounds containing a carbon-oxygen double bond, which are developed naturally in the human body in small amounts. Consuming an excess amount of aldehydes is thought to contribute to the symptoms of diseases such as diabetes.
The results also displayed that the polyunsaturated (sunflower and flaxseed) oils developed higher amounts of aldehydes at a faster rate than monounsaturated (olive) oil. In addition, the Olive Oil created less aldehydes and also at a later stage of the heating process.
The reason for this is thought to be because polyunsaturated oils contain more regions for chemical reaction compared to monounsaturated oil. Comparing the results, it is safe to say that Olive Oil is actually the best option for frying.
Nonetheless, it is essential to note that we know little about what a too high dose of aldehydes in humans constitutes. Thus far, conclusions have only been drawn from animal studies, and there is a lack of data from human studies that can be drawn upon to support these actual theories.
Experts argue that the potential risk also heavily depends on the quality and freshness of the oil, and how much it is actually heated. It can only be said that frying foods in shallow amounts of Olive Oil for short periods is unlikely to lead to exposure to aldehydes that is in far larger amounts than what the body would usually produce and it doesn’t pose a greater risk than frying with other oils.
Furthermore, it has been recommended that Olive Oil’s high antioxidant content may even help reduce the amount of possibly harmful chemicals created during heating.
Any oil that is heated beyond its smoke point will contain harmful chemicals. However, this type of heating (or burning) will also drastically affect the taste and smell of the oil. Frying foods usually does not get the oil to that point.
Frying foods, in general, is known to be the least healthy method of preparation, however using Olive Oilmay be safer than using other vegetable oils.