Choosing The Right Cooking Oil

by Kathryn Elliot
Wellbeing Magazine, 3 December 2009.

Fat on heat
The suitability of a fat for a particular cooking task is also dependant on its reaction to heat. Structural differences between the fats and the relative amounts of saturated versus un-saturated fatty acids all affect the stability of a fat and the way it reacts at different temperatures. Heat can change the structure, composition and flavour of a fat, with some burning and smoking at relatively low temperatures, while others are able to be kept at high temperatures for much longer without their flavour or chemical composition being affected.

Butter is structurally quite different from sesame oil. One is solid at room temperature while the other is a liquid. Butter is full of saturated fatty acids, which are highly stable. These fatty acids can be heated to high temperatures, with few changes occurring to their chemical structure. In contrast, sesame oil is high in poly-unsaturated fatty acids, which are more unstable. This means sesame oil is better suited for use at medium to lower temperatures, because when heated too high it undergoes fundamental chemical changes. At the oil’s “smoke point” there is a deterioration in flavour; it starts to break down into a gas and the remaining liquid gains a burnt flavour. This not only ruins your dinner; it’s also believed the remaining liquid contains larger quantities of free radicals.

When choosing an oil it is therefore important to pick one which can be heated to a high enough temperature for the cooking method you are using.

Quantity
Watch any TV cooking program and you’ll see the host adding lots of olive oil: standing there talking while pouring cupfuls of oil into their cooking. While this may work for celebrity chefs, it is not a good strategy for home cooking. Even the healthiest of oils can be overconsumed. They are energy dense, high in kilojoules and too much will contribute to weight gain.
Moreover, excess fat intake also places you at risk of some cancers and heart disease, so how much fat you use in cooking is a significant part of the health equation. Adding more than you need to your diet will harm your health, regardless of whether the fat is dominated by saturated, mono- or poly-unsaturated fatty acids. Quantity counts.

Olive oil
Over the last few years, supermarkets have set aside more and more shelves for olive oil and there’s a large range of different types available:

• Extra virgin olive oilis the first pressing of the olives. This has to be a cold pressing and the resultant oil has no more than 0.8 per cent acidity. It is a premium-grade oil extraction.
• Virgin olive oil is the second pressing. No heat or chemicals are used and the resultant oil has an acidity of no more than 2 per cent. It’s the second-best grade of olive oil.
• Pure olive oil and olive oil are usually a blend of virgin and light oil.
• Light olive oil is refined olive oil. It is a later extraction from the olives and has been chemically treated to reduce strong flavours and aromas. The term “light” refers to the taste and colour. It has the same fat and kilojoule content as the other oils.

Health effects: Olive oil is about 70 per cent mono-unsaturated fatty acids, 16 per cent saturated and 10 per cent poly-unsaturated. Mono-unsaturated fatty acids have been found to reduce total and LDL cholesterol levels and are associated with a reduced risk of heart disease.

What to use: Extra virgin olive oil is the least processed choice. It is the first pressing and likely to contain the most antioxidants and other phytonutrients.

How to use: The relatively low smoking point (190°C) means extra virgin olive oil should only be used at lower temperatures. It is best used for gently sautéing foods on a lower heat or adding at the end of cooking, to flavour the final dish. It’s also beautiful in salad dressings.

CLICK HERE to see our range of Cooking Oils