Frying is a method of cooking in which food submerged in hot oil and cooks instantly. How healthy an oil is to fry depends on how it reacts when heated. High-temperature cooking methods like frying and deep frying cause oil to break down and produce chemicals like peroxides and aldehydes, which are harmful to cells in the body.
Oils that have a high smoke point and are heart-healthy with unsaturated fats are the best oils for frying. The smoke point of an oil is the temperature at which an oil starts to break down and produce free radicals that can cause damage to cells in the body. It is important to choose oils that are most stable at high temperatures. Oils with a high smoke point may be more stable and healthy to cook than those with a low smoking point. Different oils have varying smoke points depending on what they’re composed of and how processed they are. Less refined oils like extra virgin olive oil and extra virgin coconut oil, have a shorter shelf life and a lower smoke point. Also, they are full of flavors. More refined oils like safflower oil or canola oil, have a longer shelf life and a higher smoke point, and less flavor (also known as neutral oils). Olive oil and sunflower oil are good options to use when you deep-fry foods. Other options include canola, safflower and peanut oils. Olive oil has anti-inflammatory properties and high in antioxidants and fatty acids. This makes olive oil more stable when heated at high temperatures.
Some oils can withstand at a much higher temperature than others. When you are cooking oil at high temperatures, you want to use the oils that are stable and do not get oxidized or rancid. The more saturated fats in the oil are, the more stable they are when heated. Saturated fats and monounsaturated fats are resistant to heating but the oils that are high in polyunsaturated fats should be avoided for cooking. Polyunsaturated fats contain two or more double bonds in their chemical structure and these bonds react with oxygen and form harmful compounds when exposed to high heat.