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Why Do We Use Cooking Oil, Really?

They conduct heat, carry flavors, and keep your food from sticking. Here’s why—and what else you should know.

Some things in cooking, you take for granted. When the recipe asks you to do them, you follow the instructions diligently, assuming that that’s just how it works and not daring—or caring enough—to question.

The use of cooking oil is, without a doubt, one of them. I mean, everyone knows that they shouldn’t get cooking without drizzling a bit of oil onto their pots and pans first. But have you ever wondered why that is?

You’re here, so I’m going to bet that you did. And tell you that you came to the right place. Because, with your help, I’m about to unravel why it is that we cook with oil to begin with.

Let’s get to it, then. Why do we use cooking oils and fats?

We cook with oils and fats because they transport heat, keep food from sticking to the bottom and sides of the cooking vessel, and dissolve and carry flavors from other ingredients in our food.

Cooking works best when your food comes into sudden contact with a scorching-hot surface. As a result, a crispy, flavorful, golden-brown crust forms on the outside as the food itself cooks fully through on the inside.

We cook with oil and fat instead of water because water, no matter how much it’s heated, will never exceed its boiling point of 212°F (100°C). Said otherwise, oils and fats help carry and conduct the heat from your cooking vessel to your food more effectively.

For reference, most plant-based oils and animal fats can get heated to temperatures to 375°F (and, in some cases, well above).

All cooking oils and fats have a smoke point, the threshold above which they stop to glisten and shimmer and start to break down and burn. When you see a steady stream of bluish smoke that’s coming from your pan, pot, or oven, that’s a tell-tail sign that you should reduce the heat.

Otherwise, oils will become bitter, and animal fats will burn as they form potentially harmful compounds to your health.

Cooking oils and fats also keep food from sticking to the cooking vessel—and from falling apart as you try in vain to get it unstuck—by forming a slick, non-stick-like between your food and the cooking surface.

Last but not least, they dissolve the aroma and flavor molecules that are naturally present in herbs, spices, and alliums. Some impart your home-cooked dishes with a smell and taste of their own, making them more appetizing.

Plant-Based Oils vs. Animal Fats

Your choice of cooking oil or fat matters more than you probably think. 

For starters, there’s a difference between plant-based oils and animal fats—and understanding that difference can make or break your home cooking.

Cooking oils are mostly plant-based. You’ll recognize them by the fact that they’re liquid at room temperature. A few staples, which almost all grocery stores carry, include avocado oil, rice bran oil, and olive oil.

There are unrefined cooking oils. They’re natural as they’re extracted using a minimal amount of processing, preserving the enzymes, flavors, and minerals of their source. Cold-pressed extra virgin olive oil is a good example.

Unrefined cooking oils are gentle and delicate. They’re great for dressing salads, drizzling over grilled veg, and adding to sauces, soups, and stews. Less so for high-heat cooking, as elevated temperatures can cause them to break down and burn, imparting your food with an acid flavor.

The most common kind of unrefined cooking oil is extra virgin olive oil. The ones I stock my pantry with, and which I’ve reviewed on this blog, are De Cecco Classico (mild), Basso Extra Virgin Olive Oil (peppery), and Filippo Berio Extra Virgin Olive Oil (viscous and creamy).

Then there are refined cooking oils, such as safflower and sunflower oil. Refined oils take more processing to extract—using high heat or chemical solvents—than their unrefined counterparts.

Filtered and strained, refined cooking oils are characterized by a high smoke point, so they stay stable when continuously exposed to high heat. This makes them more suitable for high-heat cooking methods than their natural, unrefined counterparts.

My go-to cooking oils for searing steak, shallow-frying chops, and deep-frying chicken are avocado oil (costly, imparts a nutty flavor on foods) and rice bran oil (affordable, has a pleasant, caramelly flavor).

Cooking fats are derived from animal sources. The best way to recognize them is by the fact that they tend to be solid at room temperature. Think of butter, ghee, lard, tallow, and duck fat. Except for butter, animal fats can be tricky to find, as not all stores have them in stock.

As with every rule, there are a few exceptions. For example, margarine and shortening are both made from vegetable oil, but they stay solid at room temperature like animal fats.

Choose your cooking oil or fat based on how much heat you’re about to use—and whether or not you want it to impart a certain aroma and flavor to your food.

Butter and extra virgin olive oil can be great choices for low- to medium-heat cooking, whereas avocado oil and rice bran oil are smarter choices for high-heat cooking.

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Written by

Jim is the former editor of Home Cook World. He is a career food writer who's been cooking and baking at home ever since he could see over the counter and put a chair by the stove.