I bet after you read this you'll be surprised at how much you didn't know. We don't fry as much as we used to but I know that so many folks still do it and since many requests and questions come from cooking noobs, I thought I'd share this detailed information on fry oils.
SELECTING THE RIGHT FRYING OIL
Once you’ve decided to deep-fry, you’ll need to purchase frying oil. However, before doing so, determine whether or not you plan on re-using the oil. If you decide to re-use your oil, you’ll want to make your purchase with this in mind.
According to the National Turkey Federation, you should choose an oil with a “high smoke point,” meaning the oil can be heated to a high temperature before smoking. Three oils fitting this criteria are 1) peanut oil, 2) sunflower oil and 3) canola oil. Of these oils, peanut oil is often the oil of choice due to the flavor it imparts on the food. However, keep in mind that peanut oil is also one of the more expensive options and some people are allergic to peanuts and peanut oil.
Smoke Point
Smoke points are the temperatures at which oil begins to decompose. It is during this process that visible fumes are given off, which includes acreolin, an obnoxious smelling compound that makes your eyes burn.
Oils have different smoke points and oils with higher smoke points are typically better for frying. Below is a list of different types of oils and their smoke points to help you when choosing the right oil to use when deep-frying.
Knowing the smoke point will also warn you about the flash point and fire point, as they are close in range. Oil has reached its flash point (600°F for most oils) when tiny wisps of fire begin to leap from its surface. If the oil is heated to its fire point (700°F for most oils), its surface will be ablaze. The appropriate temperature for deep-frying food is typically between about 347°F and 374°F. Therefore, it is important to select an oil that does not have a smoke point too close to this temperature range, as the taste of the food may be affected, not to mention the safety aspects as mentioned above. When oil is heated to the proper temperature, the batter-coated or breaded surface will quickly form a protective shield, preventing the oil from penetrating the coating and making it greasy. The food will cook by conduction (or indirect heat). If the oil is not hot enough, oil will reach the food before the coating cooks enough to form the protective layer, resulting in greasy food.
GENERAL DEEP-FRYING TIPS
As you get ready to deep-fry, review the general tips below to ensure you haven’t missed anything. Good luck!
• Use extra caution when deep-frying. Beware of splatters and spills while deep-frying, as they can result in serious burns. Have a fire extinguisher present when deep-frying. Be sure to place the deep-fryer on a solid surface to help prevent it from tipping over. Place the deep fryer a safe distance from the building. Check with your local fire department for additional safety precautions to take when deep-frying a turkey.
• Heat the oil to the right temperature. If the oil is too hot, the coating will burn from the direct heat of the oil before the food has had time to cook. If the oil is not hot enough, the food will absorb too much oil and become greasy.
• Avoid adding salt to food before deep-frying. Salt draws moisture to the food’s surface, which will cause splattering when the food is added to the hot oil. Salt also lowers the smoke point and breaks down the oil more quickly. If needed, add salt just before eating.
• No aluminum pot. Do not store used oil inside your aluminum pot. The salt used in cooking can corrode the pot causing the pot to leak.
• Do not overcrowd the deep fryer. If the fryer is too crowded with food, the oil’s temperature will lower, allowing oil to reach the food before the coating cooks enough to form the protective layer, resulting in greasy food.
• Preheat the oil. Preheat the oil to about 7 to 8 degrees C (15 degrees F) higher than its optimal deep-frying temperature due to the cooling affect adding food to the oil has. Note: Preheating it higher than this may damage the oil’s molecular structure.
RE-USING COOKING OIL
After researching this subject with numerous agencies, institutes, associations, and others around the country, we have come to the conclusion that the ability to re-use cooking oil (e.g., peanut oil) is dependent on several factors such as oil type, cooking temperature, storage temperature, product impurities, duration at cooking temperature, etc. So, if you would like to re-use your cooking oil, please read the following and check out our “links” page so you can make an informed decision.
Factors affecting the ability to re-use cooking oil
- Time. The length of time the oil is exposed to heat, light, oxygen, as well as the cooking container. The longer oil is exposed to these elements, the faster the oil will become rancid, as the oxidation process is sped up with light and heat exposure. Oil deteriorates through the action of lipase and other enzymes in the oil, and the action of oxygen. “Auto-oxidation” occurs in the absence of air and is prevented by natural anti-oxidants in the oil. Auto-oxidation proceeds slowly until all anti-oxidants are used up at which time the oil quickly becomes rancid.
- Water. The amount of moisture absorbed by the oil and how dry the turkeys are when the go into the fryer.
- Temperature. The temperature to which the oil is heated. Oil that is overheated will decompose faster.
- Impurities. The amount of impurities (e.g., batter, food particles, salt, other seasonings, etc.) in the oil. The greater the amount of impurities in the oil, the faster the quality of oil will degrade. Note: Salt lowers the smoke point of oil and accelerates degrading of the oil.
- Oils. The different types of fats and oils contained in the oil. The greater the variation of animal fats and other oils contained in used oil, the faster the rancidity process, because combining different types of fats, oils and grease lowers the smoke point.
- Number. The number of times the oil has been used. The more times an oil has been used, the faster that oil will degrade.
Basic Steps For Re-Using Cooking Oil:
Should you decide to reuse your cooking/frying oil, we have included some general directions to follow. In addition, it is always recommended to refer to the oil manufacturer’s recommendations for the use and reuse of the specific oil.
1. Turn off the heat as soon as you are finished deep-frying. Exposure to prolonged heat accelerates the rancidity process.
2. Allow the oil to cool.
3. As soon as the oil has cooled, strain and filter the oil into the original container or another sealable/airtight container. Never pour hot oil into a container, as an injury may result. Note: Straining removes the larger particles and filtering it through a few layers of cheesecloth, paper towels or a coffee filter will remove the smaller pieces.
4. Secure the lid on the container.
5. Store the strained and filtered cooking oil in a cool dark place – preferably a freezer or refrigerator. Save it for another meal unless it becomes rancid.
6. Repeat the cleaning, filtering and storing process after each use.
7. Properly dispose of the oil when the flavor of reheated oil becomes objectionable to taste. The number of times oil may be reused will vary due to many factors listed above.
General Tips For Re-Using Oil:
Use a good thermometer to fry foods at the appropriate temperature and avoid overheating.
Do not mix with different types of oils. This will degrade the oil by reducing the smoke point.
Avoid iron or copper pots/pans for frying oil that is to be re-used. These metals can accelerate the rancidity process.
INDICATORS THAT YOUR COOKING OIL NEEDS TO BE REPLACED
• Foaming – Occurs on the oil’s surface.
• Darkening – Oil darkens with use because the oil and food molecules burn when subjected to high/prolonged heat. The oil will darken as you continue to use it. However, this does not become a problem until the oil is accompanied by an unpleasant odor, excessive foaming and eventually smoke and uncontrollable flames.
• Excessive smoking – When smoke appears on the oil’s surface before the temperature reaches 375°F, your oil will no longer deep-fry effectively.
• Rancid smell – If the oil has a rancid or “off” smell or if it smells like the foods you’ve cooked in it, it should be disposed of properly.
• No bubbles – Failure to bubble when food is added to the oil is indicative of oil that needs to be replaced.
• Slow Pouring – The more an oil is used, the more slowly it will pour. Its viscosity changes because of changes to the oil’s molecular structure.
Do you have any tips to add to this list? We'd love to hear them!
