You have just finished deep frying your fish, or French fries, or whatever, and what remains in the pan is a sea of already used cooking oil.
You really hate food wastage but you are not sure if it is a good idea to reuse the leftover oil in cooking another dish.
That is probably why you are here.
If you are in a hurry to prepare the next meal using the same oil, I will give you a simple answer.
It is perfectly okay to reuse the remaining cooking oil after deep frying food as long as it doesn’t interfere with the other food’s flavor and taste.
You can also use it more than once; say 2 to 5 times depending on an oil parameter called the smoke point that determines the temperature at which the oil molecules holding it together will break down.
It is also advisable not to reuse recycled oil after it has stayed past 6 weeks.
I have personally conducted a few experiments on different recycled frying oils and very few went past the 6 weeks’ mark without showing signs of rancidity (spoilage).
So, after you finish up frying that second or third meal, you can come back here and learn more about some interesting fats and oils facts.
As for the rest, let’s buckle up and slide down the oily road.
Smoke Point, Flash Point, and Fire Point in Cooking Oil
I wouldn’t answer this question thoroughly if I don’t touch on some cooking oil jargon.
Smoke point, flash point, and fire point are very important parameters in cooking oil, especially when selecting the oil for different modes of frying.
You cannot just use any oil for deep frying, shallow frying, and normal frying.
Different oils are manufactured for different purposes and in most cases, the manufacturer will have a cooking recommendation on the container label.
There are many things that go into refining cooking oil to make it suitable for the target dish.
What is Smoke Point in Fats and Oils?
Smoke point is the temperature at which molecules holding fats and oils together disintegrate or break down making the oil to start producing smoke and burnt flavor.
Practically, this is the point where you start seeing that bluish smoke when you heat oil in a pan for some time.
This temperature is not a fixed number for all fats and oils in the world.
There are different smoke points depending on a number of factors such as the source of the oil, the methods of refinery, and the testing methods used.
Generally, the higher the smoking point for a particular oil, the better it is for deep frying.
Many oil manufacturers recommend oils with smoke point above 320 oF (160 oC) for deep frying and above 250 oF (121 oC) for shallow pan frying.
Check the table below for some smoke points for common edible oils in the market.
Cooking Oil Flash Point
If your oil on the pan reaches its smoking point and you continue heating it further, you are headed into the danger zone.
The oil is said to reach its flash point temperature when the volatile vapors being produced by the oil reach a point where they can be ignited by a source of fire around.
Smoke point generally destroys the oil’s physical state and flavor. Flash point on the other hand takes the mess further by starting a fire in your pan.
The flash point for most common edible oils is usually above 600 oF (316 oC).
If you continue heating your oil after the smoke point, you will be surprised how fast you will shift into the flash point.
To prevent such fire hazards in the kitchen, adjust the burner knobs on your cooking oven to low heat.
You always get good results when you cook anything at medium to low temperatures.
Fire Point in Cooking Oil
This is where things get explosive; quite literally.
If you are stubborn and would like to play with fire, keep up the high flame even further past the flash point.
Well, this may also happen when you are not looking or maybe when you are not aware of what is happening.
The fire point in cooking oil is the temperature at which volatile vapors from the burning oil explode violently.
Most edible oils reach their fire point at around 650 oF (343 oC).
This is also not very far if you are not keeping an eye on what is going on in your pan.
Interesting fun fact: Soap is made out of fats and oils. Ironically, it is used to clean fats and oils! That is why you will often see the same brand making cooking oil and soap.
To get some ideas on the smoke point, flash point, and fire points of some common edible oils, here is a list of typical temperature points drawn from a guideline by the institute of shortening and edible oils, Inc.
As stated in their disclaimer, these values represent typical temperature points expected for the oils.
It doesn’t mean that all oils will have that exact smoke point or flash point.
There will always be slight variations based on the factors I stated earlier (Source of oil, processing methods, testing methods, etc.)
But these figures can give you a good indication of which oil to use for your different cooking needs.
| Oil Type | Smoke Point ℉ (℃) | Flash Point ℉ (℃) | Fire Point ℉ (℃) |
|---|---|---|---|
| Refined Avocado oil | 520℉ (271℃) | 600℉ (316℃) | 700℉ (371℃) |
| Canola oil | 457℉ (236℃) | 619℉ (326℃) | 662℉ (350℃) |
| Refined Sunflower oil | 471℉ (244℃) | 606℉ (319℃) | 680℉ (360℃) |
| Coconut oil | 385℉ (196℃) | 563℉ (295℃) | 626℉ (330℃) |
| Corn oil | 455℉ (235℃) | 617℉ (325℃) | 670℉ (354℃) |
| Palm oil | 489℉ (254℃) | 615℉ (324℃) | 669℉ (354℃) |
| Virgin Olive Oil | 410℉ (210℃) | 600℉ (315℃) | 700℉ (371℃) |
| Palm olein oil | 446℉ (230℃) | 615℉ (324℃) | 666℉ (352℃) |
| Soybean oil | 464℉ (240℃) | 626℉ (330℃) | 680℉ (360℃) |
| Peanut oil | 446℉ (230℃) | 633℉ (334℃) | 680℉ (360℃) |
| Cottonseed oil | 450℉ (232℃) | 606℉ (319℃) | 680℉ (360℃) |
| Rice bran oil | 444℉ (229℃) | 615℉ (324℃) | 695℉ (368℃) |
| Beef Tallow | 446℉ (230℃) | 626℉ (330℃) | 680℉ (360℃) |
| Lard | 464℉ (240℃) | 626℉ (330℃) | 680℉ (360℃) |
| Vegetable blend oil | 428℉ (220℃) | 600℉ (316℃) | 680℉ (360℃) |
| Castor oil | 392℉ (200℃) | 446℉ (229℃) | 600℉ (316℃) |
| Butter | 302℉ (150℃) | 400℉ (204℃) | 600℉ (316℃) |
| Mustard oil | 480℉ (250℃) | 580℉ (304℃) | 650℉ (343℃) |
| Sesame oil | 453℉ (232℃) | 600℉ (315℃) | 700℉ (371℃) |
How Many Times Can You Recycle Cooking Oil Safely?
As mentioned earlier, you can reuse cooking oil as many times as possible.
But what is “possible” supposed to mean here?
Well, you cannot recycle the oil forever. There has to be a limit, considering what we have seen about the smoke point, flash point, and fire point.
It is the same logic I discussed in one of my previous articles here about expiry dates and best before dates.
For your recycled deep frying oil to be safe, you will need to keep using it below its smoke point.
Even then, the oil structure keeps disintegrating to a point it can no longer handle high temperatures.
That is the point when you need to accept and move on; and as I mentioned, it is always after about 5 recycles.
You could go past 5 recycles but it may not be safe and its quality may be at its lowest at this point.
What to do with Leftover Oil After Deep Frying
It is bad manners to waste food when someone else somewhere is having only one meal a day.
Since we do not want to degrade humanity, we shall not dispose our deep frying oil after just a single-use we now know it can be used elsewhere and it is safe.
So, what should you do with it?
Here are some steps to take after using oil for deep frying.
- Use a perforated spoon to scoop out remaining debris from the food you have been deep frying.
- Let the oil stand for a while to allow it to cool.
- Use a strainer or a cheesecloth to sieve it out to remove the remaining fine debris.
- Put it in a sealed container to avoid dust and air which will accelerate the process of oxidative rancidity.
- Reuse it for cooking compatible foods and repeat the process.
I recommend you reuse cooking oil with compatible foods for obvious reasons.
The recycled oil will most likely still have some flavor and smell of the original food fried.
Use recycled cooking oil to fry something that you wouldn’t mind the flavor from the previous food in it.
You don’t want to use the same oil for frying fish and later on, use it to fry chicken!
Your guests will smell something fishy in your chicken.
I would actually recommend you fry fish last and dispose the oil after that.
If you are doing this in a restaurant, it is good practice to always maintain separate deep frying equipment for different foods.
Recommended Oil for Deep Frying
From our table above, we can easily isolate edible oils that are suitable for deep frying and recycling.
However, not all cooking oils with high smoke points are suitable for deep frying.
For instance, virgin olive oil has a smoke point of 415 oF (210 oC) but it is too expensive to use in deep frying.
Soybean oil with a smoke point of 464 oF (240 oC) is well within the recommended deep frying smoke point range but its strong flavor could ruin your fries if you aren’t a fan.
Peanut oil smoking at 446 oF (230 oC) is a good and well-loved deep frying oil but not to people with peanut allergies. Same with mustard oil.
So, you better stick to the universally accepted deep frying oils especially if you are doing it at a commercial level.
Here are my top 10 picks for deep frying oil in no particular order.
- Avocado oil
- Corn oil
- Refined Sunflower oil
- Blended Vegetable oil
- Palm Olein oil
- Beef tallow
- Cottonseed oil
- Canola oil
- Rice bran oil
- Sesame oil
Best Way to Store Used Cooking Oil
If you are looking forward to recycling your deep frying cooking oil, it is important to know that how you store it will significantly contribute to its safe reuse.
Since the oil is not in its original condition, it is more susceptible to chemical reactions if stored under unfavorable conditions.
So, here is what you should do with the used cooking oil.
- Store the used oil in a tightly sealed container, locking out air to decelerate oxidative rancidity. This also keeps out foreign objects getting into the oil.
- The storage container should preferably be translucent or opaque to prevent light reaching the oil. Light is a major catalyst of cooking oil rancidity.
- Keep the container in a cool dry place away from heat or direct light for longevity. The best place would be at the back of your kitchen cabinet or inside a refrigerator.
- It is important to label the container as “used fish Oil” to avoid confusion if someone else wants to use the oil in your absence.
- When it’s time to dispose the oil at the end of its life cycle, do not pour it down the sink. It will clog it and you may need to call a plumber. Put it in a container and toss it in the trash bin.
Final Word
Now that you have both the good and the bad news of used cooking oil, it should be easier to make those kitchen decisions from an informed point of view.
I always advocate for recycling and reduction of food wastage and this might be another food wastage saving tip in your bag.
I hope you enjoyed this oily culinary journey.
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