Can You Leave Oil In Your Deep Fryer? (When Should You Change?)

Image of oil in a deep fryer

A deep fryer uses large amounts of oil for frying food. However, most of the oil will be left behind after frying. Now, the good news is that you can reuse the oil in a deep fryer. But, how to keep the oil until the next use? Can you leave the oil in your deep fryer?

Yes, you can leave the oil in your deep fryer, but only for a short while. Storing oil in the deep fryer can cause it to deteriorate. It’s better to remove the oil from the deep fryer and store it in an airtight container to extend its usability. You can refrigerate or freeze the oil between uses.

Let’s take a deeper look at this now.

How Long Can You Leave The Cooking Oil In A Deep Fryer?

You may already know that cooking oils have a “use-by” or “expiration” date.

If you store them properly, they remain stable and usable until this date.

Beyond the expiration date, the oil is usually unsafe for consumption.

Now, deep fryers operate at very high temperatures of at least 350°F.

When you drop food into the oil at this high temperature, it forms a crust, and the insides cook in their own moisture.

The resulting food has a crisp and crunchy exterior and a soft interior.

The important thing to note here is that you should only use an oil that’s stable at high temperatures for deep frying.

Avoid any oil with a low smoking point for deep-frying, as it can break down and release poisonous chemicals when it is overheated.

During deep frying, food particles and batter fall into the oil. If you leave it untouched, it will disintegrate over time.

So if you leave any food or batter behind, it will contaminate the oil. Remove it promptly to prevent such contamination.

Now, you may wonder if it’s fine to store the leftover oil in the deep fryer after getting rid of the food residue.

Technically, you can close the deep fryer with an airtight lid and store it as such.

However, it’s not the best way to store the oil.

You should clean a deep fryer properly between using it to avoid food contamination.

It’s a basic food safety precaution, and you would be skipping it if you leave the oil in the deep fryer.

So it’s better to remove the oil from the deep fryer and store it properly to use it multiple times.

Note that you can avoid doing this by using deep fryers that use little oil.

Recommended Further Reading:

How To Keep Deep Fryer Cooking Oil Usable For Longer?

For safety reasons, you should wait for the deep fryer to cool down completely before touching the oil in it.

Once the oil cools, you can remove it.

Strain it with a fine mesh or sieve to remove burnt food particles.

The oil will be clear at this stage, and you can transfer it into an airtight container.

We recommend using glass or ceramic containers since these materials are inert and don’t react with the oil.

You can place the containers in a cool, dry place, away from sunlight and moisture.

Nevertheless, the better option is to refrigerate or freeze the oil.

This will help you get more use of the oil than if you were to store it at room temperature.

Take care to thaw the oil thoroughly before you use it again.

Add the oil to the deep fryer only after it has completely liquefied after removing it from the refrigerator.

When Should You Change The Oil In Your Deep Fryer?

You can use the same oil for deep frying several times.

However, its reuse will depend on the type of oil, the cooking ingredients, and how well you store it between uses.

1. Oil Type

Some cooking oils are more stable than others at high temperatures.

Oils with large amounts of saturated fatty acids will usually tolerate higher temperatures than those containing polyunsaturated fatty acids.

Canola oil, olive oil, avocado oil, and vegetable oil are suitable for deep frying.

They have a high smoking point and are stable at high heat. Since these oils don’t disintegrate quickly, you can use them multiple times.

Related Further Reading:

2. Cooking Ingredients

Repeated use affects the smoking point of oils. Each time you use the same oil for deep frying, it deteriorates.

So, you can’t continue using it forever.

Interestingly, different cooking ingredients produce different reactions in the same oil.

Non-breaded ingredients like French fries don’t cause much damage.

So, you will get more use from the oil when using it to fry such ingredients.

Meanwhile, crumbly foods like meat and batter-coated foods cause the oil to disintegrate faster.

So you will have to change the oil sooner.

Another factor is that some ingredients impart intense flavors and smell to the oil.

This can affect the taste of items fried in the same oil again.

If you don’t want this mixing of flavors, it’s better to discard the oil after frying ingredients with strong odors and flavors.

3. Storing Oil Between Uses

When you leave the oil in a deep fryer, it’s exposed to moisture and temperature fluctuations.

These factors will make it deteriorate quickly.

But if you strain the oil, remove contaminants, and transfer it to an airtight container, it will store better.

It will also last even longer if you refrigerate or freeze it. The low storage temperature will keep it fresh.

Now, there is no specific rule about how many times you can reuse an oil or when you should discard it.

You can identify whether the oil is past its prime by the following factors:

  • Change in color: When you start using oil, it will be clear and free of cloudiness. However, as you use it for frying, it will become dark. When the oil takes on a cloudy appearance, it indicates that it’s past its prime. You can discard it at this stage.
  • Presence of a new smell: A cooking oil will take on the flavor of the ingredients you cook in it. With continued use, the oil will develop a distinct odor which will be evident when you take a whiff of it. It’s best to throw away any oil that has developed a distinct smell since it indicates that it’s past its prime.
  • Cooked food turns out to be greasy: When the oil is past its prime, it will make the food greasy. If you notice any change in smell, or if the food gets burnt or retains too much oil, it’s time to throw away the oil.

If you are still unsure about how many times to use an oil for deep-frying, here are some pointers:

  • You can reuse the oil three to four times for deep frying batter-coated and breaded ingredients.
  • You can reuse the oil eight to ten times to prepare fries and clean ingredients that cook quickly.
  • Don’t reuse the oil more than two or three times for frying fish, poultry, or other ingredients with strong odors.

Interesting Further Reading:

Can You Leave Peanut Oil In Your Deep Fryer?

Peanut oil is good for deep frying because it’s a plant-based fat with a high smoke point of about 445°F.

Additionally, peanut oil also has a neutral taste and fragrance.

So it will not shadow the original taste or odor of cooking ingredients and is suitable for use in deep fryers.

However, peanut oil is an expensive oil, and it can be a costly choice if you can’t use it several times.

Now, the good news is that peanut oil doesn’t disintegrate significantly when used for frying.

Since it has a very high smoking point, it will not break down easily. So you can reuse the same oil multiple times.

Additionally, peanut oil stores well. If you refrigerate or freeze the oil between uses, it will keep going for a long time.

You can leave peanut oil in your deep fryer between uses.

However, this is not the recommended way to store the oil.

Leaving the oil with any food particles in it after deep frying will contaminate it.

It’s necessary to clean the oil of any burnt food particles to extend its use.

It will reduce its smoke point and cause it to break down faster.

The better option is to remove the peanut oil after your deep fryer cools down.

Strain it using a sieve or mesh and discard any crumbs or food particles.

Store the clear oil in an airtight container in a cool, dry place, away from moisture.

We recommend refrigerating or freezing it for better results.

You can reuse the same oil for several months when you store it like this.

Check the oil before you add it to the deep fryer.

It’s best to discard peanut oil if it changes color, develops an odor, looks cloudy, or makes food greasy.

These signs indicate that the oil has disintegrated. It will be unhealthy to consume any food prepared in this oil.


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