The team noted that at 120 °C there was a 40 percent decline in the polyphenol content and a 75 percent decline at 170 °C when compared to unheated raw EVOO. The team wrote in conclusion; however, “Cooked EVOO still meets the parameters of the EU’s health claim.” […] “Despite the decrease in concentration of polyphenols during the cooking process, this oil has a polyphenol level that reaches the declaration of health in accordance to the European regulation, which means it has properties that protect oxidation of LDL cholesterol particles.”
In the Acta Scientific Nutritional Health study, 10 of the most commonly used cooking oils were selected from the supermarket and heated in two different trials. In the first, the oils were heated for about 20 minutes until they reached 464 degrees. In the second trial, the oils were heated in a deep fryer to 356 degrees, the highest temperature recommended for deep-frying foods, for six hours.
In both tests, extra-virgin olive oil displayed the greatest oxidative stability, producing lower levels of polar compounds, trans fats and other byproducts when compared with other oils that had higher smoke points.