When it comes to cooking oils, we are spoiled for choice these days. But which oil should you use, and when? Dietitian Vanessa Furlong investigates.
Cooking oils are one of the most frequently used items in the kitchen. However, not all oils are suited to all uses. Understanding the nutritional properties and composition of different oils will help you make the best choice for your dish – and your health.
Cooking oils are liquid fat derived from plants, nuts or seeds. All oils have a similar energy content (roughly 3500kJ per 100ml, or about 700kJ per tablespoon), but they can differ markedly in both the types and ratio of fats they contain. It’s this difference that makes some oils healthier than others.
Polyunsaturated and monounsaturated fats are often referred to as ‘heart healthy’ because they lower total and LDL (‘bad’) cholesterol. Monounsaturated fats also increase HDL (‘good’) cholesterol. On the other hand, saturated fats increase total and LDL cholesterol.
Being an energy-dense food, oils (even the healthier kind) should be used sparingly. The RDI for total fat is around 70g and the maximum recommended daily limit for saturated fat is 24g (but aim to consume the least amount possible). One tablespoon of oil contains roughly 18g total fat – about 20 per cent of your RDI (the saturated fat content will vary depending on the type of oil). When cooking, you should only need 1–2 tablespoons of any type of oil at most.
The smoke point refers to the temperature at which an oil starts to degrade – which affects both the quality of the oil and the flavour of the dish. The smoke point is determined by the natural composition of the oil, and how the oil has been processed, meaning it can vary slightly between different brands of the same type of oil.
Oils with a low smoke point tend to have a rich flavour and are best suited to little or no heat (making them good for dressings and dips). Oils with a high smoke point generally have a subtle flavour and are well-suited to high heat, but can also be used in sauces, dips and dressings.
High-heat cooking (stir-frying and sautéing)
Sunflower, canola and vegetable oil blends (canola and soybean oil) are the best choices when it comes to sautéing and stir-frying. They contain heart-healthy fats, have a mild flavour and are not expensive. Some of these oils are higher than others in saturated fat though, so be sure to read the label. Other good choices for high-heat cooking include light olive oil, sesame oil and rice bran oil.
Whenever possible, use spray oils to keep added energy to a minimum.
Low- to medium-heat cooking (grilling, baking and roasting)
Olive oil and vegetable oil sprays are well-suited to oven-cooking and barbecuing. If you usually brush meat and vegies with oil before cooking, try using oil in a pump spray bottle to reduce your energy intake – it provides around 8kJ per spray. When lining baking tins, we recommend using baking paper, but if you don’t have any, use an oil spray.
Coconut and palm oils are widely used in commercially-baked goods, but are best avoided because of their high saturated fat content.
Non-cooking oils (dressings, marinades, sauces and dips)
Some oils are very unstable and deteriorate rapidly when heated. In addition to affecting the flavour of the dish, the oil’s chemical structure changes so that it actually acts like a saturated fat when eaten. Therefore, these oils are best used in cold dishes. Extra virgin olive oil, some vegetable oils, flaxseed and walnut oils are well-suited to using in dressings, sauces and dips.
Which oil, when?
Avocado oil is produced from avocado pulp and is rich in healthy monounsaturated fat and vitamins A, D and E. It has a mild flavour and can be used to sauté meat, fish or chicken or to make salad dressings, despite its high smoke point.
Rice bran oil is extracted from the germ of rice grains. It’s rich in vitamin E, monounsaturated and polyunsaturated fats, but also has a relatively high saturated fat content compared to other plant-based oils. It has a high smoke point and is widely used in deep-fried Asian dishes.
Vegetable oil is usually a blend of canola and soybean oils, which are well-suited to high temperature cooking. As a guide, choose vegetable oils with 20g saturated fat or less per 100g.
Palm oil is sometimes used in vegetable oil blends, but is best avoided because it is almost 50 per cent saturated fat. The environmental issues surrounding palm oil have been hotly debated, so new labelling laws may mean that manufacturers will have to label palm oil in products.
Canola oil comes from the rapeseed plant. It is high in monounsaturated fat and has one of the lowest saturated fat contents of all oils. It contains heart-friendly omega-3s and is suitable for both low- and high-heat cooking. Canola oil is also widely used to make reduced-fat table spreads and mayonnaise.
Light olive oil comes from the second pressing of the olives and is milder than extra virgin olive oil. While many people think ‘light’ olive oil is lower in fat, in this instance the word refers to its lighter colour and mild flavour. Light and extra virgin olive oil have the same energy content, but light olive oil has a much higher smoke point.
Peanut oil is synonymous with Asian cuisine and is well-suited to stir-frying. It’s moderately high in monounsaturated fat and does not absorb or transfer flavours during cooking. If you plan to cook with peanut oil, check that nobody has a peanut allergy.
Sunflower oil is rich in vitamin E, low in saturated fat, has little or no flavour and can be used in most types of cooking.
Sesame oil has a rich, nutty taste and is well-suited to high-heat dishes, as well as cold Asian-style salads.
Grapeseed oil is one of the lesser-known oils, and it can be used in both high-heat and cold dishes. It’s also rich in healthy polyunsaturated fats.
Macadamia oil has a strong, nutty flavour and is suitable for both high-heat cooking and for use in salad dressings. It’s also very high in monounsaturated fats, making it a good choice.
Extra virgin olive oil comes from the first pressing of the olives and contains primarily heart-healthy monounsaturated fats. It is best suited to dressings, marinades, sauces and low-heat cooking (such as roasting), but can also be used for high-heat cooking. It’s green in colour and has a strong, pleasant flavour.
Coconut oil Pressed from coconuts, this oil is almost 90 per cent saturated fat, so it’s best avoided.
Walnut oil is best for cold dishes such as dressings, sauces and dips. It has a rich, nutty flavour and contains one of the lowest saturated fat contents of all oils. Walnut oil is generally found in green grocers and specialty food stores.
Flaxseed/linseed oil is rich in heart-healthy omega-3s, but isn’t heat stable and breaks down quickly – meaning it has a very low smoke point, so it’s best suited to cold dishes like salads. Flaxseed/linseed oil is also prone to going rancid, so be sure to store it in the refrigerator.
High-heat cooking oils
Alfa One Rice Bran Oil Although higher in saturated fat than olive and canola oils, it’s also high in antioxidants. Per 100g: 3400kJ, fat 92g, sat fat 21g (23% of total fats); mono 39g; poly 32g
Crisco Canola OilHas the Heart Foundation Tick and is a source of omega-3. Per 100g: 3400kJ, fat 92g, sat fat 8g (9% of total fats), mono 56g, poly 28g
Low- to medium-heat cooking oils
ProChef Canola Oil Cooking SprayPerfect for all types of cooking, including baking, and carries the Heart Foundation Tick. Per 100g: 3684kJ, fat 99g, sat fat 9g (10% of total fats), mono 59g, poly 31g
Azalea Grapeseed Oil Has a high smoke point, but is especially well suited to medium-heat cooking such as grilling or barbecuing. Per 100g: 3390kJ, fat 93g, sat fat 9g (10% of total fats), mono 23g, poly 60g
Grove Avocado Oil Sourced from New Zealand avocados, this all-natural oil contains plenty of antioxidants. Per 100g: 3350kJ, fat 90g, sat fat 13g (14% of total fats), mono 69g, poly 8g
Woolworths Select Australian Extra Virgin Olive OilThis olive oil is rich in monounsaturated fat and is 100% Australian sourced. Per 100g: 3448kJ, fat 91.5g, sat fat 13.8g (15% of total fats), mono 68.3g, poly 9.4g
Food Standards Australia New Zealand (FSANZ). NUTTAB 2010. Available at URL www.foodstandards.gov.au/consumerinformation/nuttab2010/. Accessed August 2011. Harold Mc Gee, 2004. On Food and Cooking: The Science and Lore of the Kitchen, Simon & Schuster Adult Publishing Group. The Cook’s Book of Ingredients, 2010. DK Publishing. International Olive Council. 2011. Available at URL www.Internationaloliveoil.org. Accessed August 2011.