All around the world people enjoy fried food. But how many know that cooking oils differ in their ability to withstand heat and repeated use? Now, a new study finds that compared to several seed oils, olive oil remains the most stable at high temperature and thus likely to be better for health.

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The results showed that when used as a frying oil, refined olive oil was overall chemically more stable than refined seed oils.

The researchers, led by Sfax University in Tunisia, report what they found when they compared olive oil with sunflower, corn and soybean oil, in the Journal of Agricultural and Food Chemistry.

In their paper, lead author Akram Zribi, a graduate student in the Ecole Nationale d’Ingénieurs de Sfax, and colleagues note how different cooking oils have different physical, chemical and nutritional properties, which change when heated.

When heated, cooking oils produce new compounds, some of which can be toxic or change the nutritional value of the oil.

The purpose of the study was to find out which oil remained the most stable at high temperature with repeated use. Many people use the same batch of cooking oil several times for deep frying.

The team cooked potatoes in three ways in four different refined oils – olive, corn, soybean and sunflower. The three cooking methods were: deep fried at 320 degrees F, deep fried at 374 degrees F and pan fried at 356 degrees F.

The team repeated each method 10 times with the same batch of oil – under conditions that reflected normal home use, and they used several methods to assess chemical changes in the oils during frying.

The results showed that when used as a frying oil, refined olive oil was overall chemically more stable than refined seed oils.

The authors note that the olive oil showed the “greatest resistance to oxidative deterioration, and its trans-fatty acid contents and percentages of total polar compounds were found to be lower at 160 degrees C [320 degrees F] during deep frying.”

They found the highest deterioration occurred in the refined sunflower oil during pan frying at 356 degrees F.

They conclude that olive oil is superior to seed oil for food frying because it maintains quality and nutrition better.

Funds for the study came from the Ministry for Higher Education and Scientific Research, and the Ministry of Agriculture, both in Tunisia.

Meanwhile, Medical News Today recently learned of a study that found following a Mediterranean diet rich in nuts and olive oil may reverse metabolic syndrome – a cluster of risk factors for cardiovascular disease and diabetes.