Each year, every Australian uses 5.5kg of cooking oil. But not all oils are created equal. Dietitian Lisa Yates explains how to make the right choice for your health.
Asian cuisine uses peanut and sesame oil. Mediterranean people consider olive oil a must. Some oils have a high smoke point and suit exposure to high temperatures. Others will degrade if cooked.
Cooking with the right oil can be hard to do, as different oils suit different temperatures, cuisines and flavours. And with the different proportions of saturated fats and heart-healthy monounsaturated and polyunsaturated fats, oils can affect your health differently, too. This guide will make it easy to choose the right oil for you.
Different kinds of oils
Olive: There are two types of olive oil: ‘extra virgin’, named because it’s from the first pressing of olives, has a stronger flavour and lower smoke point, making it good for dressings, marinades, sauces and low-heat cooking. Then there’s ‘light’, which has a higher smoke point, making it better for stir fries.
Canola: Made from the seeds of the rapeseed plant; it has a high smoke point, mild flavour, and some plant omega-3s.
Rice bran oil: Extracted from the germ of rice grains, it has a high smoke point which is good for stir-fries and deep-frying. It’s rich in vitamin E, oryzanol (an antioxidant) and plant sterols.
Avocado: Lightly flavoured, it carries other flavours well. It has a very high smoke point, rich in mono fats and vitamin E.
Sunflower: Made from sunflower seeds, this flavourless, vitamin E-rich oil is good for frying.
Nut oils: These oils taste like the nuts they came from: almond oil, hazelnut oil, macadamia oil, peanut oil, pecan oil and walnut oil. But only certain nut oils – those rich in mono fats – can be used for cooking. Macadamia and peanut, for example, have high smoke points, but walnut should only be used in dressings.
Flaxseed/linseed: An oil rich in omega-3 with a low smoke point. Suitable for dressings only.
Vegetable: This oil is actually extracted from legumes, fruits, grains, nuts and seeds – not vegies! Avoid buying a ‘blend’ unless ingredients are specified – otherwise you may be buying a mixture containing high levels of saturated fat-rich oils.
How to read the label
Check the per 100g column in the Nutrition Information Panel so you can compare oils.
Fat: Oils have 91–100% fat, so they’re rich in kilojoules. To make sure it contains mainly healthy mono and poly fats, look at the saturated fat level, it should be 20g per 100g or less. Fortunately, all bottled cooking oil on supermarket shelves fall into this category.
Vitamins and antioxidants: Most oils contain fat-soluble vitamin E and antioxidants like polyphenols and beta-carotene – even if not stated on the label.
Nutrition claims: Don’t be confused by the terms ‘light’ and ‘cholesterol-free’; ‘light’ refers to the colour and flavour of the oil, not the fat content, although they tend to have a higher smoke point. All plant products are ‘cholesterol-free’ as you need a liver to make cholesterol. If you have high cholesterol, always check the saturated fat of foods – your liver makes blood cholesterol from the saturated fat you eat.
How much to use
While we need a small amount of healthy fats to maintain a healthy heart, too many kilojoules from any source can lead to weight-gain. When cooking, you only need to use one to two tablespoons. Don’t use the same oils each time – mix it up with a variety of oils. Avoid deep-frying; pan-fry with only a small amount and use sparingly over hot vegies and as dressings on salads.
Don’t cook with flaxseed/linseed and walnut oils – they’re rich in poly fats, which are not heat stable and break down quickly. Instead, use their flavour to make delicious salad dressings.
Why we need it
Research has shown that oils rich in mono or poly fats are necessary for regulating blood cholesterol – a factor of heart disease and stroke. These oils help control the LDL (bad cholesterol) and triglycerides, while helping to boost HDL (good cholesterol). All oils contain vitamin E, a fat-soluble antioxidant that prevents the fats from going rancid too quickly. Cold-pressed and extra virgin oils tend to have more antioxidants than ‘light’ oils, but just one tablespoon of vegetable oil can provide up to 80% of your daily vitamin E requirement. Avoid re-using oils in cooking, as it can destroy nutrients and turn healthy oils into unhealthy saturated fats.
All about oil sprays
These cans or bottles use a gas propellant such as butane and propane and/or nitrogen to spray oils as a fine mist. Emulsifiers, such as soy lecithin, are used to keep the oil mixture in liquid form. Using spray oils on your cookware may void their warranties, so check before use.
Buying and storing
All oils are sensitive to heat, light and exposure to oxygen. Buy them in dark glass and metal cans; if it’s in clear glass, choose a bottle from the back of the shelf. It’s best to store cooking oils in the fridge or a cool, dry place. Oil should keep for four to six months once opened and longer in the fridge.
What is an oil’s smoke point?
The smoke point is the temperature at which heated oil begins to smoke and break down, affecting its flavour and that of the food being cooked. Then there’s the flash point – a higher temperature where the oil combusts, catching fire. To avoid both when cooking at high temperatures, choose oils with smoke points higher than 200°C (see ‘Comparison of cooking oils’ at right).
How are cooking oils made?
Vegetable oils are liquid at room temperature and extracted from grains, fruits, legumes, seeds or nuts. They can be extracted two ways:
Solvent extraction: The food is heated and pressed, the oil squeezed out, then crushed and mixed with solvent to dissolve the remaining oil. The solvent is evaporated off and the two batches can be mixed.
Pressing: Cold-pressed oil is pressed by mechanical means without any heat being applied which can protect the levels of heat-sensitive nutrients and the flavour.