How many times can oil be heated?

We've got some fry-tastic news

How many times can oil be heated?

Fried chicken. French fries. Doughnuts. These comfort foods all have one thing in common: They're fried to high heaven.

Now that there are many at-home fryers available, people are deep-frying their favorite treats in the comfort of their own kitchens. But that convenience comes with a cost. If you're frying often, you can go through oil pretty quickly. Well, we've got some fry-tastic news for you.

Yes, it is OK to reuse fry oil.

Here's how to clean and store it:

① Once you've finished frying, let the oil cool. When it's reached a safe temperature, use a utensil to remove any large pieces of batter that might be left over.

 Place a fine-mesh strainer or cheesecloth (even better if you use both) over the container you plan to store it in and strain the oil. Be careful when pouring, as there might be larger pieces of debris at the bottom of the fryer. Discard those separately.

 Store the oil in a cool, dry place.

There is no official rule as to how many times you can reuse oil; however, it will break down the more you use it, meaning your fried chicken could end up a soggy mess. If it's cloudy, has a funny odor or has developed a layer of film on top, it's time to swap it out for a new batch. Hopefully, this makes your frying even easier—and tastier—than before.

Can you explain the dos and don’ts of reusing frying oil? And when it is time to say goodbye, how do you dispose of it responsibly?
Chris, Fakenham

There is no denying that frying the likes of pakora and puri requires a lot of oil, so it makes sense to use it more than once. Chris is right, though: there are a few rules to follow to get the most out of the hot stuff.

First, lay the foundations. If your frying game is off, reusing your oil won’t be an option. “The most important thing is to treat it well in the first place,” says Feast’s zero-waste correspondent Tom Hunt. “This means not burning the oil or letting it smoke.” If you do play fast and loose with the heat, however, get rid and start afresh.

Frying, of course, occurs at high temperatures, so you will need an oil with a high smoking point. For Hunt, this means extra-virgin olive oil. “The smoke point is closer to that of other oils you might usually fry with than people realise,” he explains. “It’s normally about 190C. It can be lower, though, so take care to keep it from overheating.” In short, stay alert and don’t omit evoo from your frying repertoire – as Hunt points out, it has a great flavour, too.

After the first fry, Hunt leaves the oil to cool completely, then strains it through a fine sieve and cheesecloth, before storing it in a sealed container in a dark place. The chef and food writer Romy Gill, meanwhile, follows in her mother’s footsteps and houses her used sunflower oil in a glass jar, while the cook Chetna Makan keeps hers in a frying pan covered with a lid, straining it again just before use: “If there’s stuff at the bottom, it will stick to whatever you’re frying fresh.”

Then, reuse your oil a few times (six if you are Gill and frying vegetarian fare, five for Makan) – but don’t be a martyr. “Keep an eye on the state of the oil,” Hunt says. “You don’t want it to get too dark, have too much sediment or be foamy.” If it starts to smell, it’s definitely time to part ways: “It can go rancid quickly if it gets too dirty.”

It is worth remembering that oil will take on the flavour of whatever you fry in it, so discretion is key. “If you’re cooking fish, meat or something with a particular odour, keep that in mind the next time you use it,” Hunt says. While Gill never uses oil in which she has fried fish “for anything that isn’t fish”, Hunt says you don’t have to be such a stickler: “You might want some pork flavour on your fish – just not on your doughnuts.”

Another option for reducing waste is simply to use less oil. “I often shallow-fry things that you might normally deep-fry,” Hunt says. Croquettes are a good example: “I fry them in a centimetre of oil, basting and turning now and then.”

When it is time to bid farewell to your oil, never, ever pour it down the sink – your pipes won’t thank you. Most local recycling centres take cooking oil waste, so they are your best (and least messy) bet. “I always have an empty bottle to pour my oil into,” Makan says, “which I take to the tip to add to their tank for recycling.” So, oil’s well that ends well (groan).

Recipes

Some people shy away from deep frying since it seems like a waste to throw out oil after one batch. The good news is that it’s fine to reuse frying oil multiple times when it's strained—up to a point.

By Published May 29, 2019

In search of some guidelines on reusing oil, we fried chicken (thighs dredged in flour and cornstarch) and our Crunchy Kettle Potato Chips. We cooked both foods in identical Dutch ovens filled with 2 quarts of canola oil, strained the leftover oil after each fry, and used a kit to evaluate the oil, which turns it from blue to green in the presence of certain compounds that indicate degradation.

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The fried-chicken oil got progressively darker and stronger-smelling and turned increasingly green in the test kit vials, but the results were perfectly fine through four uses; only after the fifth batch did the chicken start to taste greasy and have off-flavors.

The potato-chip oil remained pale and clean-smelling and barely changed color in the test vials, producing identical chips through eight batches, at which point we stopped testing.

Our recommendation: With breaded and battered foods, reuse oil three or four times. With cleaner-frying items such as potato chips, it’s fine to reuse oil at least eight times—and likely far longer, especially if you’re replenishing it with some fresh oil.

Can heated oil be reused?

Anju Sood, "cooking oils should never be re-used as they turn rancid and increase the trans-fatty acids which are extremely dangerous for your health. Especially, avoid re-heating cold-pressed oils as they have low smoking points.

What happens when oil is heated repeatedly?

Repeated heating of vegetable oils at high temperatures during cooking is a very common cooking practice. Repeatedly heated cooking oils (RCO) can generate varieties of compounds, including polycyclic aromatic hydrocarbons (PAH), some of which have been reported as carcinogenic.

Can you use cooking oil twice?

There is no official rule as to how many times you can reuse oil; however, it will break down the more you use it, meaning your fried chicken could end up a soggy mess. If it's cloudy, has a funny odor or has developed a layer of film on top, it's time to swap it out for a new batch.

Is it unhealthy to reuse cooking oil?

Reusing cooking oil without using a deep fryer is extremely harmful to your health, according to the nutritionist. “Reusing cooking oil increases the cholesterol, creates peroxides acid , causes cancer, attacks organ cells and can infect the white blood cells.”