A definitive guide to olive oil
Photography: Teny Aghamalian
Extra virgin olive oil (EVOO) refers to the juice mechanically extracted from recently harvested, high-quality olives. The go-to term "cold pressed" is essentially obsolete in modern extraction: "Extra-virgin oil is now almost exclusively teased from the olive using the natural 'oil is lighter than water' principle," says Richard Gawel, a celebrated oil tester and presiding judge at the Australian National Extra Virgin Olive Oil shows. Cold extracted is a more accurate description.
Olive oil refers to the oily liquid extracted from low-grade olives that has been chemically refined to boost marketability. The result is a cheaper oil with high levels of monounsaturated fats. However, the refining process can influence an oil's flavour profile and aroma. Don't put weight behind words such as 'pure' or 'light' on the label - these are marketing terms with little meaning.
A quick way to determine quality is to see if an oil carries logo certification from a governing body such as the Australian Olive Association (AOA). Their strict code of practice ensures you're getting high quality, often award-winning produce.
Oil is profiled according to its bitterness and pungency. Mild oils are characterised as buttery, nutty and delicate, while robust oils are pungent, astringent and bitter. Medium oils fall somewhere in the middle with fruity, grassy and herbal flavour profiles.
All of these traits are affected by an oil's polyphenol level which is determined by the variety of the olive and its ripeness at time of picking. "A low polyphenol variety, such as Arbequina, tends to produce oils low in bitterness and pungency," advises Gawel. In terms of maturity at harvest, "the polyphenol level of ripe olives is lower than that in green olives so the bitterness and pungency of the oil will decline as picking is left later and later," says Gawel.
Let's be clear. Colour is not indicative of quality. "High-quality extra virgin olive oils can appear emerald green through to golden yellow," says Gawel.
One thing worth noting is that some green oils can have a higher chlorophyll content. Chlorophyll is affected by light exposure, so ensure your oil isn't bottled in clear glass - unless you want it to go rancid.
Oil is not wine. It deteriorates with age and will not improve.
Keep it well-sealed, away from heat and light and it should see you through 12 months. Be mindful that the flavoursome and healthy polyphenols decline over time so try to use it frequently. If that's not possible, store in the fridge to increase shelf life. As a general guide, robust oils have the best shelf life.
Refined olive oil allows for additional preservatives so, in theory, it should have a longer shelf life than extra-virgin oil. However, most refined oil is sold in clear glass bottles which decreases longevity.
There's a misconception that you can't use extra-virgin oil for cooking. Yes, it does have a lower smoke point than olive oil (170˚-210˚ depending on acidity), but it can be used to shallow fry.
Gourmet Traveller food and style director Emma Knowles suggests a mild olive oil to sauté, poach and bake, saving a robust extra-virgin oil for finishing. A medium extra-virgin oil is your best choice to team with balsamic.
Oil carries flavour, so as a general rule of thumb, pair like with like. Robust oils work with strongly flavoured or seasoned foods whereas a mild oil is bested suited to mellow flavours that would be overpowered by anything stronger.
This article is presented by ALDI, the first supermarket to sign the Australian Olive Association Code of Good Practice.