Cooking with Olive Oil
Extra Virgin Olive Oil is widely regarded as one world healthiest fats. It is packed with Omega 3 and 6 saturated fats, monounsaturated fats called oleic acid, and vitamins. These constituents can help to reduce heart disease, cholesterol levels, and even potential lower your risk of cancer. It is no wonder then, that using olive oil for cooking is an amazingly attractive prospect to maintain a healthy lifestyle.
There is much conflicting information in the media on whether olive oil for cooking is a good idea, and some sources saying that cooking with olive oil could even be adverse to your health if it is heated. This is a myth, so let’s have a look why cooking with olive oil is not only possible but also a healthier choice than cooking with other oils.
When considering if an oil is suitable for cooking, there are two main factors
• Smoke Point: The temperature that the fats in the oil start to break down. At this point you will be able to see a blueish smoke rising from the oil
• Oxidative Damage: How resistant the fats in the oil are to when reacting with oxygen.
A Quick Chemistry Lesson
In a fat each fat molecule is connected to one of three types of fatty acids. These fatty acids can either be saturated, monounsaturated, or polyunsaturated. These names allude to the chemical composition of the fat, specifically the number of double bonds in each fat molecule. Saturated fats have no double bonds, monounsaturated fats have one double bond, and polyunsaturated fats have more than one double bond. Oils generally contain more than one type of fat meaning they will probably contain saturated, monounsaturated, or polyunsaturated fats but in varying proportions so we generally just call an oil saturated, monounsaturated, or polyunsaturated buy what the majority of the fats which constitute it are.
So why is this important when cooking with olive oil? It all has to do with these double bonds. The double bonds in the fatty acids are far more unstable than single bonds when they are heated in the presence of oxygen. This means that an oil high in saturated fats are very resistant to heat, whereas polyunsaturated fats break down at lower temperatures.
The chart below shows the split of types in fatty acid in some popular cooking oils.
As you can see from the chart above over 82% of olive oil is made up from the more heat resistant saturated and monounsaturated fatty acids.
The Smoke Point
As mentioned before, the smoke point of an oil is the temperature at which the fats in the oil start to break down. The fats then break down in glycerol and free fatty acids. These free fatty acids are also more prone to oxidation , more on that later. The smoke point can be seen when a bluish smoke starts to rise from the oil, and the oil will also start to give off a foul oder. Once an oil has reached its smoke point it is inadvisable to consume it as the oxidised free fatty acids can become harmful free radicals and carcinogens.
The table below shows the smoke points of common cooking oils
Harmful compounds in oil are created when the oil reacts with oxygen, not by solely heating the oil. This can happen even at room temperature, which is one of the reasons that oils go off, but when an oil is heated this process is greatly accelerated. Heating the oil as we have seen above causes free fatty acids to be produced. These free fatty acids, especially if they contain a double bond (polyunsaturated) are far most susceptible to oxygenation.
So simply, there are two main factors when measuring if an oil is susceptible to oxidative damage
1. The number of antioxidants in an oil
2. The percentage of polyunsaturated fats in an oil
As we have seen before only about 10% of olive oil is polyunsaturated fat and is highly rich in antioxidants, making olive oil the perfect choice to cook with.
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An antioxidant is defined as any substance that inhibits oxidation, especially in relation to food products. There are many types of antioxidants in food such as beta-carotene, lycopene and vitamin C. In olive oil the main antioxidants are vitamin E, carotenoids, and phenolic compounds. The amount of antioxidants in an olive oil depends on many factors such as the climate the olives were grown, when in the season the olives were harvested, and how ripe the olives were when they were harvested.
Many scientific studies have compared oxidation levels in olive oils with other cooking oils such as sunflower and mixed vegetable, under different cooking conditions such as deep frying and sautéing. These studies have shown that olive oil is highly resistant to oxidative damage compared to traditional cooking oils.