We all know we’re supposed to go for baked or grilled when we have the option, but we all indulge in a fried food once in a while. Fried food is delicious because of the fats and oils that are infused into the food during the frying process, not to mention the crispy layer of bread crumbs that’s often added on top. Unfortunately, those two ingredients are also what can make fried food so bad for you.
New research is showing that the oil you use also matters. Oils come in two major classes: saturated and unsaturated. You can think of saturated fats as saturated with energy compared to unsaturated. Per ounce of oil, saturated fats carry more fuel than their unsaturated counterparts. Unsaturated fats also have other uses in the body aside from just energy. Omega-3s, which are a type of unsaturated fat, are used in the brain for example. How can you tell the two kinds apart? Saturated fats, like butter, are solid at room temperature and tend to come from animals. Unsaturated fats, like olive oils, are liquid at room temperature and tend to come from plants.
Knowing that unsaturated fats are better for us, the researchers in a study out this week wanted to see whether some unsaturated oils were better for frying than others. You would think all oils would be the same, but unfortunately that’s not the case. Oils from different plants have slightly different types of unsaturated fats within them that respond differently to high temperatures. In some oils, high temperatures can dramatically change chemical structure and can even break down the oil.
While some of these changes have no effect on the quality of the oil, others produce toxic compounds that can be bad for your health. The aim of the study was to find out whether some vegetable oils were more likely to break down under heat. They looked at olive oil, corn oil, soybean oil and sunflower oil. To test them, they pan fried and deep fried 10 batches potatoes in the same oil at around 350°F for about 10 minutes. When this was finished, they collected the leftover oil and looked for signs of chemical change and breakdown.
Breakdown of oil was the most dramatic in sunflower oil used for pan frying, while olive oil used in deep frying resisted breakdown the best. Olive oil was also the most resistant to chemical changes that could produce harmful chemicals in the oil. Sunflower oil showed the most damage with soybean oil close behind. Finally, dreaded trans-fats were found in all oils after the frying process, with sunflower oil topping the list again and olive oil showing only a small increase in the amount of these harmful fats.
Finally, the study found that deep frying at around 320°F is the safest way to use oils in that it minimizes the damage to the oils. Pan frying is hardest on the oils and produces the most damage and chemical change.