Frying in oil is one of the world’s most popular ways to prepare food — chicken and French-fried potatoes are staples but even candy bars and whole turkeys have joined the list of deep-friend goodness.
Lots of oil make health claims but there is a whole range of physical, chemical and nutritional properties that can degrade oil quality when heated so a paper in the Journal of Agricultural and Food Chemistry tested four different refined oils — olive, corn, soybean and sunflower — and reused the oil 10 times to determine which is truly the best.
The answer: Olive oil. When heated, some oils can form new compounds that are potentially toxic, and by-products of heating oil can also lower the nutritional value of the food being fried.
Mohamed Bouaziz and colleagues found out that under high heat and repeated use, olive oil withstands the heat of the fryer or pan better than several seed oils to yield more healthful food. They deep- and pan-fried raw potato pieces in olive, corn, soybean and sunflower oils 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.