The benefits of extra virgin olive oil are only when eaten raw, combined with salads. But there are other kinds of olive oils (not extra virgin), which can be used for frying. Scientists report in ACS’ Journal of Agricultural and Food Chemistry that olive oil withstands the heat of the fryer or pan better than several seed oils to yield more healthful food.
Mohamed Bouaziz and colleagues note that different oils have a range of physical, chemical and nutritional properties that can degrade oil quality when heated. Some of these changes can lead to the formation of new compounds that are potentially toxic. By-products of heating oil can also lower the nutritional value of the food being fried. Bouaziz’s team wanted to find out which cooking oil can maintain its quality under high heat and repeated use.
The researchers deep- and pan-fried raw potato pieces in four different refined oils — olive, corn, soybean and sunflower — and reused the oil 10 times. They found that olive oil was the most stable oil for deep-frying at 320 and 374 degrees Fahrenheit, while sunflower oil degraded the fastest when pan-fried at 356 degrees. They conclude that for frying foods, olive oil maintains quality and nutrition better than seed oils.
The authors acknowledge funding from the Ministère de l’Enseignement Supérieur et de la Recherche Scientifique and the Ministère de l’Agriculture, Tunisia.