Fat is almost as essential for cooking as heat, and you’ll struggle to find a single kitchen that doesn’t contain a bottle of cooking oil. But which one should you be cooking with, and when? Most of us will have a collection of bottles, so here’s a short guide to the most common edible oils that you’ll have in your kitchen and what to use them for.
What Does Cooking Oil Do?
Cooking oil is most often used for frying, roasting or baking, and fulfills a number of important roles. Oil transfers heat from the pan to the food, and because oil can be heated to a much higher temperature than water it allows food to be cooked faster. It also acts as a lubricant to prevent food from sticking to the cooking surface. Fat is a flavour carrier so improves the taste of food, and also the texture because oil facilitates the Maillard reaction, which is what gives us a crispy, golden crust on fried or roasted foods.
Oil For Flavour
Oils aren’t only used in the kitchen for frying. As well as enhancing the flavour of a dish they also have flavour in their own right, and can carry flavour. The choice of oil used in a salad dressing will have a significant impact upon the flavour of the dressing, and oils flavoured with chilli, garlic, truffle and so on are often used to add that flavour to a risotto, pizza or similar dish.
How Edible Oils Are Produced
Some oils, such as olive oil and coconut oil, are made by pressing the flesh of the fruit, however most oils are extracted by pressing the seeds (sunflower oil, rapeseed oil, sesame oil, peanut oil and so on) and then in many cases solvent extraction is used to collect the maximum yield. Taking olive oil as an example, the different types and grades available are based on how the oil was extracted – extra virgin olive oil comes from the first cold press, and has the strongest flavour. The second press will be heated to help extract more oil and the product will be lighter in colour and flavour, and so on. Sunflower, rapeseed and peanut oils can also be cold pressed by squeezing the oil out of the crushed nut or seed. Cheaper oils, of the sorts used in high volumes for frying, are pressed and then the “oil cake” of crushed seeds has any remaining oil harvested by a process called solvent extraction which uses a volatile hydrocarbon to dissolve the oil out of the cake before using fractional distillation to remove the solvent. These oils are then refined (unpleasant sounding industrial processes to “degum”, “bleach” and “deodorise” the oil) before bottling. You can see why so many chefs advise you to buy good quality oil, particularly for use in salad dressings.
The Cookery School’s Store Cupboard Selection, From Left to Right:
Extra Virgin Olive Oil
Extracted from the first cold pressing of the olives, this oil has a richer, sometimes “earthier” flavour so is great for salad dressings or dips where you want that flavour. You can cook with it, but it has a low smoking point and it’s expensive so you might want to save it for specific uses rather than frying your eggs in it.
Cold Pressed Rapeseed Oil
A lighter oil for cooking or salad dressings with a delicate nutty flavour. Rapeseed oil is high in mono-unsaturated fats so is one of the only unblended oils that can be heated to high temperatures for frying without the risk of spoiling. Rapeseed is the bright yellow flowering crop that fills British fields in the early summer months, meaning that you can buy locally produced rapeseed oil (because there aren’t too many olive groves here in the UK).
Olive Oil
It’s good to have a lower grade olive oil to hand for occasions where you don’t need or want to cook with your precious first cold pressed! Virgin olive oil also comes from the first pressing but is slightly more acidic and can be used for cooking. Standard “pure” olive oil is blended and its flavour is blander, but it is a good multi-purpose cooking oil.
Sunflower Oil
Sunflower is your go-to cooking oil for higher temperature methods, such as roasting, frying or deep frying, because of it’s high smoke point (the temperature at which the oil starts to smoke). It has a mild flavour so is a great general cooking oil, but wouldn’t be a good choice for salad dressings.
Sesame Oil
A must if you cook any Asian cuisine, sesame oil is great for stir-fries, dressings and marinades. It has a pretty intense nutty flavour, so you’ll know when you’ve used it.
White and Black Truffle Oil
Flavoured oils are often the sorts of things that you might bring back from holiday, or that a relative might give you for a gift. They’re also super common in hampers. Truffle oil is wonderful though. Because of the high value of truffles, infusing slices in oil is a great way of imparting some of the highly sought-after aroma and flavour into a dish. White truffles are one of the world’s most expensive foods, so don’t expect these bottles to be big or cheap! Truffle oil is strictly a finishing oil, to be drizzled over a dish just before serving (don’t cook with it!) – creamy dishes such as risotto are the most obvious choice, but have you ever drizzled truffle oil over scrambled eggs?
Chilli Flavoured Rapeseed Oil
Another “back of the cupboard” bottle, so many of us will have bottles of infused oils that don’t often see the light of day. These are finishing oils for drizzling over things like pizza – this chilli flavoured rapeseed oil makes the most of the rapeseed oils delicate flavour to focus on the chilli. You might have a similar bottle of garlic or herb infused oil, or you can make them yourself.