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The Ultimate Guide to Cooking Oils

The type of oil with which you cook can make a big difference on taste.
The type of oil with which you cook can make a big difference on taste.
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For professional and amateur chefs alike, cooking oils are an essential part of the culinary process. Cooking oils are natural substances, mostly derived from plants. One of the most popular uses is for frying or sautéing, which cooks food quickly and usually adds a crunchy exterior texture. Cooking oils are also used to flavor dishes, marinate meats and vegetables, or to dress salads.

So, what are the different kinds of cooking oils? Most cooking oils fall into the category of vegetable oils, a blanket term given to any oil that comes from vegetation. "Vegetable oil" can also refer to a blend of different types of vegetable-based oils. There are many oils on the market, and most are identified by their plant or tree of origin. Canola oil is a popular product, derived from the canola plant; olive oil is widely used in Mediterranean cuisine; grapeseed, sesame, sunflower, flax and safflower oils are all derived from the seeds of their parent plants. Nut-based oils include peanut, walnut and almond. Oils from corn plants, coconuts and oil palm trees have also been popular among commercial food manufacturers, but they've become increasingly controversial in recent years due to their adverse health effects.

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Ever find yourself in this situation? We're here to help.
Ever find yourself in this situation? We're here to help.
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Knowing which cooking oils to use -- and when to use them -- can be tricky. Because heat is often involved, it's important to know the smoke point of the oil with which you're cooking. The smoke point refers to the temperature at which the oil begins to break down. After that, free radicals start to form and the risks to your health increase. So, staying below the smoke point is important. Extra virgin olive oil, for example, has a relatively low smoke point, and you shouldn't use it for, say, deep-frying. On the other hand, peanut oil has a smoke point of 440 degrees Fahrenheit, and it's much better suited for deep-frying. Oils prized for their flavor, such as walnut oil, are used less often for cooking and more frequently as a dressing; heat breaks down the more delicate flavors, so many foodies consider cooking with walnut oil to be a waste.

So, back to the big question: How does cooking oil affect your health? See the next page to learn which cooking oils mean trouble for your cholesterol.

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Check the levels of fat in your cooking oil before purchasing it.
Check the levels of fat in your cooking oil before purchasing it.
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It's important to consider the health benefits and risks of cooking oils. All of them fall at different places on the spectrum of "healthy" fats versus "bad" fats. While some are considered to be detrimental to your health, others actively improve it. But before we dive in, let's examine the different types of fat found in cooking oil.

By now, most people understand that trans fats are unhealthy. This kind of fat is added to food as a preservative, and it also keeps it from feeling overly greasy. The drawback is that trans fats raise your bad cholesterol (low-density lipoprotein, or LDL) and lower your good cholesterol (high-density lipoprotein, or HDL). And, while other types of fat are a necessary part of a healthy diet, trans fats are completely superfluous. Saturated fats also raise bad cholesterol levels, though they occur naturally in animal products. Unsaturated fats, both mono and poly, are considered to be much healthier. Unlike trans and saturated fats, mono- and polyunsaturated fats can lower your overall cholesterol, especially your levels of LDL. When you're choosing a cooking oil, look for higher levels of unsaturated fats and little or no trans and saturated fats.

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Olive oil is considered healthy for cooking.
Olive oil is considered healthy for cooking.
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Which cooking oils are considered unhealthy? As we've already mentioned, palm oil, coconut oil and corn oil are examples of cooking oil that are bad for you -- that's because they're high in saturated fat. Any vegetable oil blend that's described as "partially hydrogenated" means that it's high in trans fat.

On the other hand, lots of cooking oils can actually have a positive impact on your health. Flax oil, for example, contains omega-3 fatty acids. Omega-3s are an essential part of a healthy diet that our bodies don't produce naturally, so we've got to get them from certain foods. Among other benefits, these fatty acids promote good brain health. Olive oil is another healthy option. It's a source of monounsaturated fat, one of the "good" fats that lower your overall cholesterol.

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Now you know which oils to pick up at the market. But how do you store them once you bring them home?

Dark, glass bottles will keep your oil from going bad too quickly.
Dark, glass bottles will keep your oil from going bad too quickly.
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Should you keep oil in the pantry or the refrigerator? For the most part, you should store oil in the refrigerator, or at least in a cool, dry place. There is, of course, an exception to every rule -- some varieties of extra virgin olive oil, for example, shouldn't go in the refrigerator. Condensation can develop within the bottle, which will affect the flavor. (Always be sure to read the product label to find the manufacturer's recommendation for that specific type of oil.) Both light and heat have a detrimental effect on oil. Darker containers can help, but that will only add a brief span to the shelf life if it's left in a well-lit area. Oxygen will also speed up the process of decay, and for that reason many oil manufacturers will fill the negative space in the bottle with an inert gas such as nitrogen. Most oils will thicken when refrigerated, but they'll quickly return to a liquid state when left standing at room temperature.

Then there's the question of containers. Traditionally, dark glass bottles are best for most types of oil; the dark color protects the oil from light, and glass doesn't interact with the oil itself. However, stainless steel, ceramic and porcelain vessels are all good alternatives. And unless you work in a restaurant that quickly goes through a lot of cooking oil, avoid plastic storage containers: The oil can absorb chemicals from plastic, including polyvinyl chlorides (PVCs).

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Keeping cooking oil in a dark, cool space will prolong its use.
Keeping cooking oil in a dark, cool space will prolong its use.
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Both refrigeration and a good-quality container can extend the life of the oil, but nothing lasts forever. Though expiration dates for cooking oils vary, most begin to go rancid within six months to a year. Rancid oil lacks the flavor and health benefits the oil had in its prime, and it's darker in color. You'll also notice a change in odor. And, like oils that are cooked past their smoke points, rancid oils can produce free radicals. All in all, it's better to cut your losses and get rid of rancid oil.

But disposing of used or rancid cooking oil isn't as easy as you'd think. Rinsing it down the drain isn't a good idea, since it can build up in your pipes and lead to slow or clogged drains. It can even result in problems for city sewer systems. Public works departments recommend putting cooled oil into a sealable, non-recyclable container and disposing of it.

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There's certainly more to cooking oils than meets the eye. Still have questions? See the links on the next page for lots more information.

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Sources

  • Alleman, Gayle A. "How Olive Oil Works." HowStuffWorks.com. (June 27, 2010)https://recipes.howstuffworks.com/how-olive-oil-works.htm
  • Blonz, Ed. "You'll Know if Cooking Oil Becomes Rancid." San Diego Union-Tribune. Aug. 20, 2008. (June 25, 2010)http://ww.uniontrib.com/uniontrib/20080820/news_1f20focus.html
  • Chu, Michael. "Smoke Points of Various Fats." Cooking For Engineers. June 10, 2004. (June 9, 2010)http://www.cookingforengineers.com/article/50/Smoke-Points-of-Various-Fats
  • Elaioladiki Organic Extra Virgin Olive Oil. "Storage Tips." (June 9, 2010)http://www.elaioladiki.gr/en/olive_oil_storage.htm
  • Mayo Clinic. "Dietary Fats: Know Which Types to Choose." (June 10, 2010)http://www.mayoclinic.com/health/fat/nu00262
  • Mayo Clinic. "Trans Fat: Avoid This Cholesterol Double Whammy." (June 10, 2010)http://www.mayoclinic.com/health/trans-fat/cl00032
  • New York City Department of Environmental Protection. "Grease Disposal Tips to Help the City's Environment." Jan. 19, 2007. (June 26, 2010)http://www.nyc.gov/html/dep/html/residents/congrease.shtml
  • Tsang, Gloria. "Cooking Oil: How to Choose a Good One." HealthCastle.com. May 2007. (June 10, 2010)http://www.healthcastle.com/cooking-oils.shtml
  • WellSphere.com. "Right Way of Storing Cooking Oil." Sept. 13, 2008. (June 10, 2010)http://www.wellsphere.com/healthy-cooking-article/right-way-of-storing-cooking-oil/352858
  • WhatsCookingAmerica.net. "Olive Oil." (June 9, 2010)http://whatscookingamerica.net/OliveOil.htm

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