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Fried foods are among the most popular comfort meals across the globe. One may even say that they’re the type of food that brings people together the most, as deep-fried snacks are a staple for parties, family get-togethers, or even sports events.

In fact, food or snacks that are cooked in oil are also one of the food groups people crave the most when they’re on a diet.

But, if you’re guilty of using up a gallon of oil to achieve that fast-food-like deep-fried taste at home, you might have a lot of oil that has now been used once. What do you do with all the oil once you’re done cooking? Is that safe to reuse? Many recipes online do not tell you exactly what kind of oil to use; can you use anything? All of these questions are quite common and very valid.

But in order to come to a verdict on whether deep frying is healthy or not, or if you should reuse it; we first need to talk about the different types of oils, what their uses are, and what causes them to behave differently during the cooking process.

Types of Cooking Oils: What’s the Difference?

There are numerous types of oils available on the market. Some, like olive oil, are well-known, while others like grapeseed or avocado oil are less-known or even unknown by most people, but they are slowly gaining popularity nowadays because of their health benefits.

Oil is produced from a wide range of plants’ seeds and fruits. Some oils such as sunflower, olive, and canola oil are widely used and therefore usually produced on a large scale. On the other hand, grapeseed, linseed, or walnut oil can be produced on a smaller scale for personal use. This is because they have more specific uses and are also usually less profitable to produce.

But how can we tell which oil is the healthiest option? Can you cook and fry using the same type of oil? Let’s explore different types of cooking oils and find out.

In order to have a better understanding of why different oils have different uses, it’s a good idea to explain what the “smoking point” of oil is.

What Does “The Smoking Point” Mean?

Different types of oils have different smoking points. The smoking point is the temperature at which the oil starts to create smoke; an indication that it’s starting to burn. At this point, the oil’s qualities begin to quickly deteriorate and the cooking oil becomes unsafe to use.

It’s important to note that going above the smoking point may cause the oil to combust and can lead to serious injuries, so it’s always a safe practice to stop heating your cooking oil once it starts burning.

Smoking points can also vary between the refined and regular versions of the same type of oil. This is because refined oils are rich in various minerals and enzymes and are, therefore, more flavorful.

For example, the smoking point of refined olive oil is higher than regular olive oil. This is why refined oil is more widely sold as cooking oil, although it won’t taste nearly as good as the unrefined olive oil on a cold salad.

Here’s a list of some of the most popular cooking oils’ smoking points, from the highest to the lowest:

  • Refined Avocado Oil – 520°F (271°C)
  • Refined Olive Oil – 465°F (240°C)
  • Refined peanut oil – 450°F (232°C)
  • Ghee/Clarified butter – 450°F (232°C)
  • Corn/Sunflower oil – 450°F (232°C)
  • Canola oil – 400°F (204°C)
  • Grapeseed oil – 400°F (204°C)
  • Extra virgin olive oil – 375°F (190°C)
  • Butter – 300°F (148°C)

Best Oils for Cooking

As mentioned above, unrefined or “raw” oils are oils that have been left in their natural state. These oils tend to be packed with flavor and they also provide more health benefits than refined oils.

Unrefined oils, on the other hand, have lower smoking points and oxidize more rapidly when they are exposed to heat. This is why it’s generally recommended to use these types of oils in low-heat cooking and sauteing, or just heat them up without allowing them to reach their smoking point. It’s also a great idea to use them in salad dressings. Unrefined oils also require better storage conditions as they can go bad easily.

For any kind of high-heat cooking like frying or deep-frying, it’s recommended to use oils with higher smoking points. You can never go wrong here with refined avocado oil or refined peanut oil, which is arguably the most popular oil used in Asian cuisine.

Since the health benefits of the oil come from whether it contains more unsaturated fats than saturated fats, flaxseed, olive, and canola oil are among the cooking oils you can always rely on. To find out more, you can read our article titled Can you deep-fry with olive oil?, which explains the health benefits of olive oil.

How Long Does Used Cooking Oil Last?

Having learned about types of cooking oils and their smoking points brings us to our main question: how long does used cooking oil last? You may have already realized that this question also depends on what kind of oil is being used, whether it’s refined or unrefined, and whether it has been stored properly or not.

Ideally, cooking oils should not be reused. But it’s most certainly not an uncommon practice to reuse deep frying oils. So the next best is this: as long as you take good care of your cooking oil, it should be fine for a couple more uses. The important point here is to remember that even if you have done everything to take great care of it, you shouldn’t cook with used cooking oils for longer than 1-2 months.

Is It Safe to Reuse Cooking Oil?

Whether it’s safe to reuse cooking oil depends on what is the specific oil you’re using, yes, but it also largely depends on what your cooking technique is. If you’ve heated your oil past the burning point during the cooking process, you probably don’t want to cook your food using that oil again.

When deep-frying, maintaining the cooking oil at a certain temperature is not only crucial for getting the right amount of crisp on your snacks but it’s also important to keep the cooking process as safe as possible. As long as you fry your food at around 190°C (374°F), your cooking oils should last longer.

What Changes Does Cooking Oil Go Through After Use?

As explained above, you can only reuse your cooking oil so many times. Once your oil is destabilized by being exposed to high heat too many times, not only will the taste and the color start to change but the oil will also eventually start to decompose.

Although it’s easy to tell when your oil starts decomposing, due to it starting to thicken in consistency and darken in color; it’s not always easy to spot a destabilized oil. To prevent using oil that is no longer healthy, make sure to open up your deep fryer to smell the oil. If it has started to go bad, it may also be bubbly or foamy on top, or its color may change.

It’s always a good idea to check every once in a while to see if your used or unused cooking oils are in good shape and make sure to throw away anything that looks or smells suspicious immediately.

Is It Possible to Clean Used Cooking Oil?

As explained above, taking good care of your cooking oil after you use it is crucial if you want to reuse it. Here are some helpful tips to help you successfully recycle your cooking oils:

  • You can strain your cooking oil after it cools down with a fine strainer or cloth to remove leftover food or batter pieces. Leaving these in will cause your oil to deteriorate faster.
  • After straining all the leftover bits, store your cooking oil in the fridge to keep it fresh longer.
  • When you deep-fry food, try not to use too much batter to avoid further contaminating the oil as much as possible.

How Long Does Unused Cooking Oil Last?

Since we’re on the subject, let’s now talk a little bit about how long you should keep an open bottle of oil. As long as you store your oil in dark, low-temperature storage, the general consensus seems to be that most popular cooking oils like refined sunflower oil, peanut oil, or olive oil can be stored for up to 2 years.

However, this does not mean that your oil will be in the best shape for the duration of 2 years -the taste and color are bound to deteriorate over time. If you want to get the best tate out of your oil, it’s recommended to not use an open container of cooking oil for longer than 6 months.


We all love deep-fried food, but not everyone wants to be involved in the process of actually making it. We get it: it’s a stressful process, you don’t know what to do with the oil after you’re done cooking, and there’s a lot of hearsay about what not to do. But now that you’ve learned the basics, you can safely enjoy cooking your favorite fried dishes!

As long as you maintain a safe temperature while cooking, strain and refrigerate your oil after you use it, and don’t use your cooking oil for more than 1-2 months, you should be fine.

And lastly, remember to check on your deep fryer to see if there’s any abnormal smell coming from the oil, or if it has deepened too much in color. In case of any suspicion, the best practice is to replace the oil to ensure the deliciousness of your food, as well as your safety.

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