Ask Peter: Cooking oils

I am trying to branch out into some new recipes, but every recipe seems to call for a different type of cooking oil. I couldn’t possibly keep up with using up so many oils.

I use olive oil all the time, but also bought roasted sesame for some (now forgotten) recipe. Which oils can I substitute for others in a recipe? My next recipe calls for peanut oil, but is it worth buying? If you wanted to just have three oils in your pantry, what would you choose? How long does an oil keep in the pantry? Christine

Recently I had a similar question about vinegars and the same has been asked about salt and sugars and could be asked about grains, pasta shapes and the like. As a collector and hoarder of all things culinary (and ceramics too, I must admit) I have exactly 23 different oils in my pantry. There are eight different extra virgin and virgin olive oils from Turkey and Greece through to Spain, Italy, France and Waiheke Island.

I have a gorgeous saffron-yellow extra virgin British rapeseed oil (rapeseed is canola oil), and a bottle of canola oil. I have rice bran oil, various sesame oils, nut oils (walnut, hazelnut, peanut and almond), grapeseed, sunflower and a toasty dark and sticky German pumpkin seed oil.

I have avocado oil from 2 countries and I have an argan oil from Morocco that is delicious drizzled over soups and yoghurt but I’d never cook with it. Argan oil is also appearing in various skin care and hair care beauty ranges. So perhaps I’m the wrong person to ask.

However, for cooking you need to understand that the reason some oils occur only in particular cuisines is that that’s what grows in the region. For example, a lot of Southeast Asian recipes call for peanut oil rather than olive oil simply because olives aren’t grown commercially in the Malaysian Highlands or Southern China, and I don’t know of any commercial Italian peanut farms producing oil.

However, that doesn’t mean you can simply swap one oil for another. The smoke point of oils — and also their flavour — will determine what they’re good for.

For example, the reason we drizzle hazelnut oil over a blue cheese, crouton and endive salad is that it is delicate and flavoursome from the bottle — the subtle nutty aromas are delicious and tasty — but heat the oil and you lose all those characteristics. Also it has a low smoke point, which means that the lipids (the fats) break down at a low temperature and the oil can become slightly rancid and burnt-tasting. Plus, it’s expensive compared with sunflower oil, so you just don’t cook with it.

Peanut oil, on the other hand, has a high smoke point (it doesn’t break down quickly when heated to 180C for deep-frying or when used in a fiercely hot wok) and it’s also an almost neutral taste, so your tofu stir-fry doesn’t taste like peanut butter. Oils with high smoke point include sunflower, canola, peanut, sesame, rice bran, avocado and light olive oils.

Oils that shouldn’t be heated above 180C include extra virgin olive oils, argan, pumpkin seed, hazelnut, almond and walnut. All of these latter oils are best used for their flavour rather than cooking ability and drizzled on finished cooked dishes or used in salad dressings.

That doesn’t mean the other oils can only be used to cook with of course — as we know sesame oil, especially toasted sesame oil, is delicious used in dressings, and I’m sure most of you use sunflower oil in salad dressings and mayonnaises. Having said all that, I was intrigued many years ago watching a cooking show with Antonio Carluccio where he cooked fritto misto in extra virgin olive oil.

I’d been told never to fry, even shallow fry, in extra virgin olive oil and here was one of the great Italian chefs frying fish and sage leaves in a batter in 3cm of very hot olive oil. I queried it with Italian friends and they were split on it — most saying it was more an expensive extravagance and wasteful rather than it was bad for the food.

I fried some fish in it a short time later and it was delicious, but it was expensive, and the oil broke down shortly after, meaning it could only be used once or twice — unlike the usual deep-frying oil which can be used 3-6 times before it tastes old or tainted with the food that’s been fried with it.

I’ve also decided that making mayonnaise with extra virgin olive oil is a bad idea as it seems to make the mayonnaise quite bitter. What I do is use a neutral oil like sunflower or a light olive oil, then add extra virgin at the end, say 20 per cent of the total volume of oil. I suspect (with no scientific evidence to back me up) that the over-whisking or food processing somehow transforms the taste of the oil.

Back to your three oils. I’d suggest picking one ofsunflower, rice bran or canola for deep-frying. You can use sesame or peanut (or one of the previous three) for wok frying, and extra virgin olive oil for finishing dishes. As for how long it keeps, check the bottle, but if it smells slightlymusty before you use it, then discard.

In our Ask Peter series, executive chef Peter Gordon answers your curly culinary questions. If you're stumped over something food-related, send your question to askpeter@bite.co.nz and keep checking in for answers. You can read more on Peter on his website, have a read of his Ask Peter articles or check out his recipes on our site.