We use cooking oils for frying, baking, stir-fries, salads and marinades, but choosing the right one can be confusing. Consumers are bombarded with all different types of oils – not to mention all the different descriptors such as "extra light" and "cold-pressed".
Then of course there are health concerns, particularly around levels of saturated fat. So when it comes to cooking oils, which one should you use?
The fat factor
While all fats supply the same amount of energy to the body (1g of fat provides 37kJ), not all fats are created equal. Fats are the body's most concentrated source of energy and help protect and insulate your vital organs. They also allow fat-soluble vitamins (A, D, E and K), to be absorbed and provide essential fatty acids, which are important building blocks for the brain, eyes and nervous tissues. So what are these different types of fat?
- Saturated fat is the main dietary cause of high cholesterol, raising levels of the harmful low-density lipoprotein (LDL) cholesterol in the blood. Too much saturated fat heightens your risk of heart disease.
- Trans fat behaves similarly to saturated fat. However, it not only raises levels of harmful LDL cholesterol, but also lowers levels of the good high-density lipoprotein (HDL) cholesterol. To earn the Heart Foundation tick, vegetable oils must contain no more than 1% trans fat as part of their total fat content.
- Monounsaturated and polyunsaturated (omega-3 and omega-6) fats are the types you should aim to include in your diet. They're essential nutrients for the body, and also reduce the levels of the harmful LDL cholesterol. Keep in mind, however, that these fats still provide kilojoules, so only use them in moderation.
It's generally recommended that less than 30% of your daily kilojoule intake should come from fat, with no more than 10% coming from saturated fat.
You can largely avoid the bad fats – saturated and trans – by staying away from processed and fast foods. When it comes to cooking, make your meals heart-friendlier by using a small amount of the right oils (instead of butter or margarine), adding nuts and seeds to stir-fries and salads, and including avocados in your diet. This will provide your body with the good monounsaturated and polyunsaturated fats it needs.
Cooking oils explained
Cooking oils are a combination of all the different types of fats. When it comes to cooking, we use oils in a wide variety of ways. But you don't need to buy a whole range, as some are versatile and multi-purpose. Using non-stick cookware and trying to stir-fry, grill or bake your food rather than deep-frying it will reduce your need for oil.
Almond oil is high in monounsaturated fat and comparatively low in saturated fat, so it's a good heart-friendly choice. Like mustardseed oil, almond oil has a strong nutty flavour and aftertaste. It's a low-heat oil, so it should only be used to drizzle over vegetables, in salad dressings, or to make mayonnaise.
Avocado oil is very high in monounsaturated fat, but comparatively low in polyunsaturated fat. It's packed with the fat-soluble vitamins A, D and E, and also contains B-group vitamins. Avocado oil is green in colour with a mild flavour and pleasant aftertaste. It's a low-heat cooking oil and a great addition to salads, poultry and seafood. But it is more expensive than other oils.
Canola oil is high in monounsaturated fat and a good source of omega-3 fatty acids. It's versatile and comparatively inexpensive; you could easily replace peanut or vegetable oil with canola oil in the kitchen as it's much higher in monounsaturated fat and lower in saturated fat. It performs very well for low-heat cooking and has no strong aftertaste, allowing the food flavours to dominate. It also performs well for high-heat cooking purposes.
Canola and red palm fruit oil is high in monounsaturated fat and a good source of omega-3 fatty acids, as well as pro-vitamin A and vitamin E. It has a medium smoke point, making it a good multipurpose oil; however, in a chip-frying test we found it has a slight smell and unpleasant taste. Carotino claims its red palm fruit oil comes entirely from environmentally sustainable plantations in Malaysia.
Coconut oil has a slight nutty flavour and works well in both savoury and sweet dishes. It's particularly popular in vegan cooking and can replace dairy products to make pastry and creamy desserts. Coconut oil has a very high smoking point when cooking and has a long shelf life, but it's very high in saturated fat.
Corn oil is effective in lowering blood cholesterol levels because it's high in polyunsaturated fat. It has a high smoke point which makes it ideal for frying, and its mild flavour means it's good to use for baking where oil is only needed to provide moisture and texture. It performs well for both low- and high-heat cooking; however we found it developed a slightly unpleasant smell when frying chips.
Grapeseed oil is high in polyunsaturated fat, and not only lowers the bad LDL cholesterol but also raises levels of the good HDL cholesterol. It's a rich source of vitamin E and has a light, pleasant taste that brings out the flavours of the other foods being cooked. It's a good multi-purpose oil.
Macadamia oil is very high in monounsaturated fat but comparatively low in polyunsaturated fat. It's also relatively expensive and has a strong strong nutty flavour and aftertaste, making it better for stir-fries and salad dressings than, say, making a mayonnaise.
Mustardseed oil has the lowest saturated fat content of any edible oil. It also has a good balance of omega-3 and omega-6 fatty acids. In cooking, it has a distinctive strong flavour and very nutty aftertaste that can overpower the rest of the dish.
Olive oil is a great source of monounsaturated fats and a key ingredient in the Mediterranean diet – a heart-healthy style of cooking that traditionally includes fruits, vegetables, pasta and rice. Olive oil is best used for low- to medium-heat cooking in salads or marinades.
Palm oil is commonly used in manufactured and fast foods. Its low-cost production makes it a cheaper option but it has also raised a number of environmental concerns, particularly around deforestation. At 51% it's also high in saturated fat, making it suited for processed food, but obviously a less healthy option. Currently there is no obligation to label palm oil.
Peanut oil is widely used in Asian cuisine and works well for high temperature cooking, especially for frying and stir-frying. It's predominantly monounsaturated, but in comparison to the other oils it is lower in both monounsaturated and polyunsaturated fats and comparatively higher in saturated fat. If you're cooking for guests, check no-one has a peanut allergy before using the oil.
Rice bran oil has one of the highest amounts of saturated fat, but is free of trans fats. It performed excellently for chip-frying and can be used in all cooking practices.
Sunflower oil comes in two main varieties. Normal sunflower seeds will make polyunsaturated sunflower oil rich in vitamin E. Monounsaturated sunflower oil requires special breed of sunflower seeds. Both varieties help reduce cholesterol levels. Sunflower oil is versatile for cooking; it works well for high-, medium- and low-heat temperature cooking. It's also comparatively good value for money.
Vegetable oil generally contains a combination of canola and soybean oil. It's comparatively inexpensive, but also comparatively high in saturated fat. It's worth noting that palm oil and coconut oil can also be labelled as 'vegetable oil', which can be an issue seeing as palm oil contains 51% saturated fat and coconut oil contains a staggering 90% sat fat.
Who knew cooking oils could be so complicated? Here are some commonly used terms – and what they mean:
- Cold-pressed oils aren't extracted using excessive heat. As a result, they generally have a stronger flavour and are higher in antioxidants such as vitamin E and polyphenols.
- All oils are from cholesterol-free, as oils are derived from plant sources that naturally have no cholesterol.
- Blended vegetable oils are made from mixture of oils depending on availability and price. For example, vegetable oils generally contain a mixture of soybean and canola oil.
- Lite/Light/Extra light only means the oil is lighter in flavour and/or colour, not lower in kilojoules.
- Extra virgin olive oil is extracted from the first pressing of olives. It yields the best-tasting and lowest acidity oil, and therefore comes with a higher price tag. It's best suited for cold purposes such as salad dressings, drizzling over cooked pasta or char-grilled vegetables.
- The smoke point of an oil refers to the level of heat it can withstand before it begins to smoke. Oils with a high smoke point are ideal for frying. Once an oil begins to smoke it will start to lose both flavour and nutritional quality and becomes more prone to bursting into flame (i.e. its flash point).
- High-heat oils generally have a high smoke point, allowing them to reach high temperatures, and can be used for deep-frying, stir-fries and sautéing.
- Medium-heat oils can be used for sautéing, baking, grilling and roasting.
- Low-heat oils generally have a low smoke point and shouldn't be used where heat is involved. They're best for cold dishes such as salad dressings and dips.
- Rancid oil develops a distinct smell akin to crayons, musty paint or paint thinner, whereas fresh oil should be fairly odourless. When heated, rancid oil has a strong and unpleasant smell. Older oil can also become more viscous and stick around the cap of the jar.