Essential in all our kitchens, oil is at the heart of many of our favorite recipes, whether it’s for seasoning a salad or for sautéing, roasting or frying food.
Each oil takes its name from the nut, seed, fruit, plant or grain from which it is extracted, and is generally designated according to the most prevalent fat, whether saturated, polyunsaturated (PUFA) or monounsaturated (MUFA).
Fats and oils play an important role in cooking because they efficiently conduct heat, prevent food from sticking to the pan, and enhance the taste and mouthfeel of the food we cook.
Scientifically speaking
Oils and fats are made up of smaller chains of fatty acids. When these chains are held together by single bonds, they are called “saturated” fats; when there are double bonds, they are called “unsaturated” fats.
There are three types of fatty acid chains: short, medium, and long. The length of these chains determines how our body metabolizes them and their efficiency in providing us with energy.
Some oils are better suited than others for high-temperature cooking, because oils change their structure when heated.
When a recipe calls for frying food, we expose the oil to increased temperature, additional moisture from the food, and oxygen from the air – all three trigger chemical reactions, which cause changes that can impact the oil, including its taste.
The extent of the changes depends on the temperature used, the cooking time, the oil chosen, and the presence or absence of protective antioxidants.
Choose an oil
One of the first things to consider is how the oil has been processed, as this will influence its behavior during cooking and, ultimately, its safety. Labels stating “virgin” or “extra virgin” indicate that the oil has undergone minimal processing, without the use of chemicals.
The term “cold-pressed” indicates that the oil was extracted without heat and that, therefore, the nutrients and enzymes will remain in the finished product. Oils with these descriptions are often called unrefined oils.
Refined oils, on the other hand, are processed using chemicals.
They may have a greater tolerance for heat because the refining process removes nutrients, enzymes, and other sensitive compounds that are more likely to burn. However, they may contain chemical residues and will not retain their natural nutrients or enzymes, although they will benefit from a longer shelf life.
Which cooking oils are the healthiest?
1. Olive oil
Photo credit,Camille Delbos/Art In All of Us/Corbis via Getty Images
A key component of the Mediterranean diet, olive oil is made from the juice of the olive and is known for its many health benefits, from protecting against heart disease to reducing the risk of type 2 diabetes.
Olive oil is a monounsaturated fatty acid (MUFA), meaning it has only one double bond, which makes it more resistant to changes during cooking. In fact, oleic acid, the predominant MUFA in olive oil, is reportedly 50 times less likely to oxidize (combine with oxygen) than linoleic acid, the predominant PUFA in vegetable oils like sunflower and corn oil. If you choose extra virgin olive oil, you’ll also benefit from the protective antioxidant properties of numerous polyphenols and nutrients such as vitamin E.
Smoke point:
Refined – 200-240C (465F)
Unrefined – 160-190 C (375F)
Verdict: For temperatures up to 180-190°C, virgin olive oil is an excellent choice. Even better, extra virgin olive oil (EVOO), made from pure, cold-pressed olives, is said to have the lowest oxidation rate of all cooking oils. Extra virgin olive oil is therefore an ideal choice for home cooking, provided it is not overheated. If you do a lot of deep frying and are on a budget, you can opt for refined olive oil and change it regularly when using prolonged cooking methods.
2. Avocado oil
Pressed from the fruit of the avocado tree, this oil is often compared to olive oil. It is rich in monounsaturated fatty acids (MUFAs), particularly oleic acid, which increases the oil’s stability at high temperatures. Numerous studies confirm its many health benefits, including for the cardiovascular system. Avocado oil has a higher smoke point than olive oil, whether refined or unrefined.
Smoke point:
Refined – 270C (520F)
Unrefined – 190-205°C (400°F)
Verdict: While avocado oil has multiple uses, including frying, sautéing, browning, and roasting, it’s relatively expensive, which may limit its use in everyday cooking. Its subtle flavor allows the other ingredients in your recipe to shine.
3. Rapeseed oil
This general-purpose oil contains half the saturated fat of olive oil, is rich in monounsaturated fatty acids (MUFAs), particularly oleic acid, and contains polyunsaturated fatty acids (PUFAs) with a favorable ratio of omega-6 to omega-3 fatty acids (2:1). Rapeseed oil also has the highest polyphenol content of all seed oils, although it should be noted that oil quality depends on several factors, including harvesting, storage, and the extraction process.
In some countries, the term “rapeseed oil” refers to the type of oil used for industrial purposes, while canola oil is the edible cooking oil. However, in the United Kingdom, the term “rapeseed oil” is used interchangeably for both types of oil, and the term “canola” is rarely used.
Smoke point:
Refined – 204-246C (475F)
Unrefined – 204 -230C (450F)
Verdict: A useful choice when a neutral-flavored oil with the right smoke point is needed for stir-frying, grilling, and baking. When choosing rapeseed oil, opt for a cold-pressed version, as it has a superior fatty acid profile and a higher content of protective polyphenols, carotenoids, and vitamin E.
4. Ghee (clarified butter)
Ghee is made by simmering butter – the moisture evaporates, the milk solids are removed, and what remains is a clear, golden oil. The low moisture content combined with the high saturated fat content gives ghee a high smoke point and a long shelf life. It is also free of lactose and casein, a milk protein, making it a suitable option for people with lactose intolerance or milk allergies.
Studies comparing the use of ghee to that of vegetable oils at temperatures of 180°C suggest that ghee produces less harmful acrylamides than vegetable oils.
Smoke point:
Refined – 250C (485F)
Unrefined – 232C (450F)
Verdict: Thanks to its high smoke point, ghee is suitable for high-temperature cooking, particularly roasting and frying. However, for baking, butter, with its milder flavor, is a better choice, unless you have a lactose intolerance or dairy allergy.
5. Coconut oil
Although coconut is referred to as an oil, it is actually a fat that liquefies at a temperature slightly above room temperature. It has a distinctive flavor and texture that create a unique mouthfeel and may not be suitable for all dishes. Composed primarily of saturated fats (92%), coconut oil has received considerable attention due to its relatively high content of medium-chain fatty acids.
Due to its high saturated fat and low unsaturated fat content, coconut oil is more resistant to oxidation than unsaturated oils such as sunflower and olive oil. Despite this, it has a relatively low smoke point, which is why its use in deep frying or prolonged deep-frying can lead to the production of harmful substances, including polycyclic aromatic hydrocarbons.
Smoke point:
Refined – 232C (450F)
Unrefined 171C – 175C (350F)
Verdict: Choose virgin coconut oil, as the extraction methods used ensure a higher content of antioxidants, including vitamin E and protective phytonutrients. It’s best to use this oil sparingly in your diet due to its high saturated fat content, lack of essential fatty acids, particularly linoleic and linolenic acids, and relatively low smoke point. Save it for stir-fries and baking.
