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An Introduction to Cooking Oils
There are many different cooking oils available and it can be confusing to know which one to use for which dish. Some examples of oils include olive oil, canola oil, sunflower oil, soybean oil, grape seed oil, peanut oil, sesame oil, and palm oil. Some oils are flavorful and others have very little taste. They also have different purposes and characteristics.
What is Cooking Oil?
Cooking oil is purified fat of animal or plant origin. It is stored as a liquid at room temperature. You can get specific types of cooking oil or the generic "vegetable oil" which is a blend of oils, usually based on corn, soybean, sunflower, or palm oils.
When you heat an oil, its characteristics change. Oils differ in their heat tolerances. For example, sunflower oil, peanut oil, grape seed oil and soybean oil can be used for high temperature frying and heating them to above 500ºF is fine. Walnut oil, sunflower oil, sesame oil and canola oil are suitable for medium temperature frying and unrefined oils should not be heated over 225ºC.
Oils for Frying
If you are using oils to make fried food, you must use an oil with a high smoke point, which is the temperature to which you can heat the oil without smoking. The best oils for frying are soy oils, safflower, peanut and sunflower oils. Canola oil usually works well too.
The normal temperature for frying is between 325ºF and 375ºF but often between 375ºF and 400ºF are fine too. Most foods cook well between 325ºF and 375ºF, developing a good flavor and golden color. Foods cooked in this temperature range absorb between 8% and 25% oil. Higher temperatures mean thinner crusts and less oil absorption. Lower temperatures mean less flavor development, a paler color, and more oil absorption.
When you think of deep-fried food, perhaps you think of North American "fast" food. The truth is that deep-frying can be traced back to ancient Europe and Asia. Fat would be rendered from the meat, then used to cook exotic dishes more quickly than if the food were roasted or stewed.
We are now more aware of the high cholesterol content in animal fats and more healthy vegetable oils, such as Canola Oil, are becoming more commonplace. Vegetable oils also have a higher smoke point than animal fats.
Refined Cooking Oils
Refined oils have been extracted from clean oil or oilseed cakes by solvent extraction. These oils are clear and free from foreign matter. They can be used for shallow or deep-frying. If you have a bland, pale oil, it has almost certainly been bleached, refined, and deodorized.
Refined oils have little flavor, which makes them good for making delicately-flavored dishes. They can be used for baking, stir-frying, sautéing, and oven cooking. You can also use refined cooking oils to sear meat or fish or to cook tempura.
How to Store Cooking Oil
All oils are sensitive to light, oxygen and heat. If oil is rancid, it will smell and taste bad and will have lost most of its nutrients. It is best to keep your cooking oils in a dry, cool place. You can keep them in the refrigerator but allow them to reach room temperature before using them.
If you are using a refined oil, which is high in monosaturates, it should keep for a year. Olive oils keep for several years. Oils high in polyunsaturated fats keep for about six months. Virgin or extra virgin olive oil usually keeps for nine months or more after being opened. It is worth investing in a selection of different oils, since they last so long!
Used cooking oil should never be disposed of down the sink or the toilet because it can block pipes. Put unwanted oil into a sealable container and throw it out with the garbage.
