Foodie Blog

Cooking Oils

The goddess Athena gifted the olive tree to the people of Athens, a dove carried the olive branch to Noah, and olive oil is credited with the unusually low rates of heart disease found throughout the Mediterranean. It even tastes great.

Olive oil is everywhere. New Zealand brands win international awards, and while the supermarket shelves are full of relatively cheap imported brands, the delis and specialist food shops sell very much more expensive lines – both local and imported. Nor is olive the only oil to make a splash. Nuts, seeds, avocados and other foods all give up their oil for gourmet cooking.

So how do you choose which oil to use for what purpose? How do you look after and get the best from your gourmet oils? Are some oils tastier, healthier or more suitable for cooking with than others?

Olive oil comes in two main styles: pure and extra virgin. The International Olive Oil Council’s (IOOC) definition of the latter is: “Oily juice from olives picked at the optimum time from a healthy tree and processed mechanically without the addition of heat or chemicals.” Beyond this, extra virgin olive oil has a wide variety of tastes due to differences in climate, soil and olive variety – there are more than 60 varieties of olive grown for oil production.

Extra virgin olive oil (EVOO) can be extracted by either centrifugal force or hydraulic pressure. There is very little difference in oil quality, provided these operations are carried out properly.

To be extra virgin, the oil must have an acidity content of no more than 0.8 per cent.

It may also be assessed by an IOOC-trained sensory panel to ensure it does not have any of the flavour faults (there are five main ones) that commonly arise from poor processing methods.

PURE OLIVE OIL

Pure olive oil, by comparison, has almost no flavour of its own. Most of the taste comes from a small amount of EVOO added before bottling.

Pure olive oil is refined, which means it is extracted (usually under heat) and put through various chemical processes to remove unwanted flavours, impurities and toxins.

Refined oils are usually colourless and odourless, so colour and flavour have to be added back. In the case of pure olive oil, a small amount of extra virgin oil, or perhaps hazelnut or another oil, will be used. It’s not quite as “pure” as you might think!

THE DIFFERENT TYPES OF FLAVOUR

Extra virgin olive oil has a much fuller taste than pure oil but both are classed in three styles: delicate, medium and intense. The general rule is, the tastier the food, the tastier the accompanying oil should be.

Delicate oils will complement a green-leaf salad and other subtly flavoured foods, such as steamed vegetables or chicken. The medium oils are better for pasta, sautés and drizzling on vegetables. Intense olive oils are great drizzled over barbecued meat.

Medium and intense oils are also best for dipping, when you want to focus on the big flavour hit from the oil.

Other flavourings, such as lemon juice and balsamic vinegar, should be used sparingly with a good oil.

The greener the better? Well, no. I asked Jacqui Dixon of Sabato about the variations in colour. Her shop imports many gourmet oils, and she says: “The brightness of the green is not a factor in quality with any olive oil, because olive leaves can be crushed with the olives to make it greener.”

Watch out for an attractively packaged version of olive oil on the market called pomace oil. Pomace is not a gourmet product – it’s what’s left of the olives when they have had all the oil pressed out of them.

Chemical solvents are used on the pomace to extract what pressing could not and the residual oil is then refined. Pomace oil may contain some pure olive oil to make it a little tastier, but don’t be fooled.

NEW ZEALAND OILS

New Zealand growers generally choose not to compete in the mass market, so almost all the oils they produce are quality EVOO. The best are very good indeed; our growers have won several major awards overseas.

But oils, like wines, vary year by year and new labels pop up all the time so, to help shoppers, the local industry has developed a quality assurance scheme under which it allows oils that make the grade to display a red seal on the label. This shows they have been certified by the Olives New Zealand Sensory Taste Panel as New Zealand EVOO.

Beyond this, it’s not easy to choose an olive oil. Most don’t tell you on the label how intense they are, so it pays to buy from a shop where they know what they’re selling.

I asked Margaret Edwards, olive grower, industry consultant and an international olive oil judge, for some advice on choosing an oil. “The only way to know which ones suit you best,” she said, “is to taste as many as possible before you buy – at promotional tastings in shops, or whenever the opportunity presents itself.”

INFUSED OILS

Infused olive oils can be a lovely way to add another layer of flavour to your food. Delicately flavoured infused oils can be ruined by heat so are better used for finishing a simple dish or for dipping with breads. Stronger infusions such as garlic, however, are designed for cooking as they are too overpowering straight from the bottle.

ORGANIC OILS

Foods are supposed to be true to the claims on the labels so, theoretically, anything labelled organic should have been produced in accordance with full organic guidelines.

But standards vary internationally, and “organic” imported oils may contain traces of non-organic products. To avoid this, sticking to New Zealand organic oils is a safe bet, and choose those with the BioGro Certified Organic trademark or the AgriQuality Organic Stamp of Approval. These show the production process has been audited and meets high organic standards.

AVOCADO OIL

Avocado oil has a gentle flavour and slightly green colour, making it a perfect partner for chicken, salmon and salads. You can cook with it, but I prefer to drizzle it over food, add it to dressings and use it as a condiment, all of which preserve the subtle complexity of this delicate and uniquely New Zealand oil.

Infused avocado oils are on their way. Keep an eye out for the garlic or pepper infusions, and try them drizzled over your favourite creamed soups.

SEED OILS

Some of the excellent seed oils include sunflower, hemp, pumpkin, mustard and flax. Check the label to see whether the oil is cold-pressed or refined. They have many health attributes. Flaxseed oil, for example, is said to help normalise the gastrointestinal functions, while hemp seed oil is one of nature’s most perfectly balanced essential fatty-acid oils.

Grapeseed oil is a cooking oil with a light, almost neutral flavour. Generally, seed oils are good for light dressings, frying and marinades, although some have a strong flavour and you may want to combine them with other milder oils.

NUT OILS

Nut oils come from walnuts, almonds, hazelnuts, peanuts and macadamia nuts among others. Like olive oils, the best nut oils are generally cold-pressed and unrefined. They have a nutty flavour and smooth consistency, and can make divine vinaigrettes when paired with lighter acids such as lemon juice or top-quality vinegars.

Nut oils are usually more flavourful than regular salad oils, so you need less to dress a salad.

RICE BRAN OIL

Rice bran is a by-product of milling rice left over once the grains have been hulled. Oil from the hulls or bran is extracted by cold-pressing, followed by refining and deodorisation.

Rice bran oil makes a good cooking oil. It has a neutral, delicate flavour, a high smoke point and a low absorption rate – the food being cooked will absorb up to 20 per cent less oil than other cooking oils. It is also rich in vitamins, minerals and other goodies that help promote good health, and claims to be the most hypoallergenic of all oils.

HOW TO STORE YOUR COOKING OILS

It might be handy to have your cooking oils sitting next to your stovetop, but it ruins the oil. It’s best to keep them in a cool, dark place.

Dark glass bottles are better than clear glass, and tins are even better again. Margaret Edwards stores her oil in the fridge. It may turn cloudy, but she says this won’t hurt it – she has won gold competing with the world’s best at the prestigious LA County Fair with oil that has been chilled to preserve its quality. Take it out of the fridge before using, to return it to room temperature.

But Eduard Pons, a leading Spanish oil producer, disputes this advice and says a cool, dark pantry is better. All oils will go rancid over time, and refining does not slow the process down. New Zealand extra virgin oils have a shelf-life of 18 months to two years if stored correctly and unopened, but are best used within a year of production. Once open, they should be used within a few months.

HEALTHY OIL?

Unsaturated fats, found in most vegetable oils, are better for you than the saturated fats found in animal products and the trans fats used in a lot of commercial cooking.

Saturated fats and trans fats raise the blood levels of “bad” cholesterol, or LDL. The presence of LDL also lowers good cholesterol, HDL. LDL clogs arteries, while HDL helps keep your arteries clear, so the goal is to lower LDL and raise HDL.

Polyunsaturated fats, found in cheaper cooking oils like safflower and soya, lower both types of cholesterol.

Monounsaturated fats lower LDL and raise HDL. Olive oil is monounsaturated, but so are several other vegetable oils like canola, peanut and avocado.

As far as is known, olive oil has no special health-related properties, that make it better for you than any other monounsaturated oil.

If in doubt, compare the nutritional information of different oils on the back labels – look for the overall kilojoule content and the saturated fat content.

The Heart Foundation’s red tick can be a useful guide. But note that not all monounsaturated oils have applied for the right to carry the tick.

And light olive oil? This is not a health claim. Light olive oil is refined with no added EVOO. “Light” refers to flavour and consistency, of which there is little.

HOT OIL COOKING

A slosh of New Zealand extra virgin olive oil can be delicious in pasta, or drizzled over barbecued meat. But there’s little point in using it to sear the meat in the first place, because when oil gets hot enough to start smoking, it also starts to lose its flavour. If you want an oil for high temperature cooking, use a cheaper olive oil or perhaps a gourmet oil with a high smoke point – like rice bran or grapeseed.

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Article © Genevieve Knights