Can you cook with extra virgin olive oil?
The benefits of extra virgin olive oil have been recognised since biblical times. Popular diets, such as the Mediterranean diet, have taught us that it’s possible to consume a high-fat diet and still have a lower risk of heart disease. But when it comes to cooking with olive oil, is it still as healthy for you after heating?
Here’s everything you need to know about cooking with extra virgin olive oil . . .
Choosing a good oil
There are many interesting flavours—fruity, peppery, buttery, and now even infused oils (chilli, lemon, garlic)—but the best types to buy are cold pressed extra virgin olive oils, in a dark bottle or can. These contain more than 45 different phytonutrients with antioxidant properties and have been linked to health benefits for heart disease and breast cancer as well as protection from ageing.
The grades of processing are important when it comes to choosing the best quality oil. Oils that have been minimally processed retain the highest content of polyphenols and antioxidants. ‘Extra virgin’ is the cream of the crop and as the grades decrease from ‘virgin’ to plain ‘olive oil’ and finally ‘light’ and ‘extra light’ the benefits diminish too.
Contrary to popular belief, light oils offer no less calories than their counterpart; they’re merely lighter in colour. ‘Cold pressed’ means little or no heat treatment has been used to extract the oil from the olive, so there are no chemical changes to the oil.
Olive oil is best used within 12–14 months from the time of harvest. Australian olive oils are harvested between March and June each year. Look for the harvest date on the front or side of the bottle to ensure you’re buying the freshest and healthiest oil.
What happens when you heat oils during cooking?
Oils generally contain a mix of saturated, monounsaturated and polyunsaturated fats, however, the ratios vary depending on the type of oil. Thinking back to high school chemistry, you might remember that polyunsaturated fatty acids (PUFA) have multiple double bonds. These are the sites of potential damage and restructuring of the fatty acid chain when heat is applied.
Heating oils containing more PUFA cause the formation of free fatty acids and other toxic compounds (e.g. polar compounds), which affect the acidity and stability of the oil. It’s these oils that are more closely linked to chronic disease.
Extra virgin olive oil is unique to other oils, with high levels of antioxidants which protect the integrity of the oil throughout the heating process. High quality extra virgin olive oil has a smoke point between 200 and 215°C, which is above that of standard home cooking temperatures (e.g. sauté 160°C, deep fry 180°C, oven baking < 200°C).
While other oils may have higher smoke points, that isn’t necessarily the best indication when choosing a cooking oil. You only need to choose an oil with a smoke point above your cooking temperature—extra virgin olive oil fits that bill in most cases!
How does extra virgin olive oil compare to other oils?
Preliminary results published in the Modern Olives journal in 2017 show that extra virgin olive oil far outranks other types. The researchers compared Australian extra virgin olive oil, olive oil (refined blend), canola oil, rice bran oil, grapeseed oil, coconut oil, peanut oil, sunflower and avocado oil under standard domestic heating methods—pan frying (sauté) at 120°C, deep frying at 160-180°C and oven baking below 200°C.
The results found Australian extra virgin olive oil performed substantially better than other common oils and, after heating, contained only trace amounts of trans fats while retaining a high level of antioxidants. The poorest performing oils were canola, grapeseed and rice bran which produced many polar compounds as well as high levels of trans fats.
The message that you can’t cook with extra virgin olive oil is an absolute myth. In fact, the opposite is true. It appears from this latest research that extra virgin olive oil is the best oil to cook with. Due to its high level of antioxidants, stability under heat, and rich source of cancer-fighting polyphenols, it’s always been the staple in our kitchen!
Sue Radd is an Advanced Accredited Practising Dietitian and one of Australia’s leading nutritionists and health communicators. Her most recent book Food as Medicine: Eating for Your Best Health received the Gourmand World Cookbook Award for Best Health and Nutrition Book in the world for 2016.
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Category: Physical Health