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Old 11-29-2016, 02:28 PM   #1
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Should cooking oil be reused after deep frying, any health concern??

After deep frying, should the oil be used again? How many times could I use it before it should be disposed ? Is the reused oil bad for health? Where should I store the reused oil ?

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Old 11-29-2016, 02:36 PM   #2
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Yes, it varies, no, in the container it came in.

I reuse fryer oil several times. After use, I let it cool and strain it through a cotton cloth and store it in a plastic jug such as the container it came in. With each reuse, I add a little oil to make up for the oil lost in cooking. How many times you reuse it will depend on what you fry. Proteins such as meat and fish will deteriorate oil faster than veggies and can leave a smell/taste behind with fish.

Used oil will be darker and its smoke point drops. If it smokes at normal frying temps, it's time to recycle it.
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Old 11-29-2016, 02:37 PM   #3
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It depends on what you deep fried. Meat, poultry or fish will flavour the oil, but vegetables, like French fries, could be fried up to 5 times in the same oil.

I have a big black funnel that my gold coffee filter fits perfectly into and I pour the used oil back into the original plastic jug it came in, then throw the funnel and filter into the top rack of dish washer
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Old 11-29-2016, 03:05 PM   #4
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Yes, it varies, no, in the container it came in.

I reuse fryer oil several times. After use, I let it cool and strain it through a cotton cloth and store it in a plastic jug such as the container it came in. With each reuse, I add a little oil to make up for the oil lost in cooking. How many times you reuse it will depend on what you fry. Proteins such as meat and fish will deteriorate oil faster than veggies and can leave a smell/taste behind with fish.

Used oil will be darker and its smoke point drops. If it smokes at normal frying temps, it's time to recycle it.

I will most likely only fry onion rings or other vegetables, which is the food I like most. I will not deep fry any meat. How many times can I reuse? Can you suggest because I guess I am unable to determine when the oil is dark enough to recycle.

I forgot a more important question: How long can I store the used oil before the next use? Will the used oil go bad if it's stored so long??

And btw, how to know if the oil is hot enough for deep frying?
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Old 11-29-2016, 03:12 PM   #5
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Oil can be reused quite a few times. If stored properly it can be used dozens of times if you don't mind using darker oil. Onions can really impart flavors, and so will fish. Breadcrumbs can burn and leave a bitter flavor. If you just use it for potatoes you can use it many times. Even when it gets dark. Just make sure to filter it between uses so you don't get the black burnt bits on your food. Some restaurants will change fryers once a week. That's a lot of uses...
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Old 11-29-2016, 07:00 PM   #6
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I use my oil several times over.

As stated be sure to filter it between uses and storage.

I use a coffee filter for this.

I also store it in an old oil container.

If you feel it imparts an off flavor then by all means change it.
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Old 11-29-2016, 11:24 PM   #7
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I hate to be the fly in the ointment here, but food isn't as good tasting after a second use of the oil. Sometimes the first.
Kinda directly converse to making tea; you can get multiple flushes but the latter suffer. Whereas tea becomes weak, frying oil picks up unpleasant flavours.
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Old 11-30-2016, 12:38 AM   #8
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I've just read a PDF slide created by a Professor on the topic of reused oil

It looks like he always discourages re-using oil. He has shown a lot of statistics to suggest that reused oil is bad for health and may lead to heart disease or cancer

I guess I will only re-use it 2-3 times in short time

Cooking oil is really expensive here.
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Old 11-30-2016, 12:44 AM   #9
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Read an article just recently on this and really no different than what all has been said here. They did say approx. 4 or 5 times was sort of the turning point with the oil, but no one can give a definitive answer as everyone fries different foods in different ways.

I would suggest you get a thermometer, it really is the best way to prevent your oil from getting too hot and burning. There is a way of testing the temperature by using a cube of bread. timing it within a certain length of time to crispy brown and the temp is usually correct. But this is chancy and unreliable timing. So sorry, I don't remember how long that time should be. A thermometer is a good investment. Saving the price of tossed burnt food is worth it.

Have you never actually deep fried before? You can't help but notice that the original pale golden colour of the oil will slowly change to brown after several uses. Still unsure? Keep a little fresh oil in a small clear glass jar. As you are returning your used oil to its bigger container, pour a little into another small clear glass jar - compare.
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Old 11-30-2016, 12:51 AM   #10
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It looks like he always discourages re-using oil. He has shown a lot of statistics to suggest that reused oil is bad for health and may lead to heart disease or cancer

I guess I will only re-use it 2-3 times in short time

Cooking oil is really expensive here.
Yes, but did he say what those oils temperatures reached while people were using them? It was mentioned earlier that overheating oils start to break down much faster - ergo probably no longer healthy. I could be wrong but I believe the colour of your oil as you use it is the good indication of condition.

Again - it really is what you are frying. French fries are one thing. Battered vegies as in tempura - that's messy LOL but delish!
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Old 11-30-2016, 01:35 AM   #11
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I've just read a PDF slide created by a Professor on the topic of reused oil

It looks like he always discourages re-using oil. He has shown a lot of statistics to suggest that reused oil is bad for health and may lead to heart disease or cancer...
Be careful of online advise given by "experts". You know the popular phrase "lies, damned lies, and statistics"? Be cautious about those "statistics", as they can be used by some to back the view they are pushing.

Years ago I heard someone say that anyone with a computer and a fax machine could become a "Foundation". The same can be said today about websites and "experts".

Since you mention that cooking oil is very expensive where you live, you might want to read over this information I found at Serious Eats. SE is one of the websites I trust; they run all sorts of tests on whatever the subject is to make sure they get it right.

How Many Times Can I Reuse Fry Oil?
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Old 11-30-2016, 06:24 AM   #12
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Be careful of online advise given by "experts". You know the popular phrase "lies, damned lies, and statistics"? Be cautious about those "statistics", as they can be used by some to back the view they are pushing.

Years ago I heard someone say that anyone with a computer and a fax machine could become a "Foundation". The same can be said today about websites and "experts".

Since you mention that cooking oil is very expensive where you live, you might want to read over this information I found at Serious Eats. SE is one of the websites I trust; they run all sorts of tests on whatever the subject is to make sure they get it right.

How Many Times Can I Reuse Fry Oil?

I will not trust those experts totally

But I remember the chemistry lesson I studied in high school suggested that heating oil/ fats is not good, I forget the details though

Just do not know the number of times I can re-use the oil
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Old 11-30-2016, 09:21 AM   #13
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Just do not know the number of times I can re-use the oil
Until just before you don't feel comfortable using it again.

There is no specific answer Kenny1999. As you will have noted there are just too many things that will affect the oil. Only you can tell how it goes.
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Old 12-01-2016, 04:46 AM   #14
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I use 1/2 olive oil and 1/2 sunflower oil for deep frying. I test the temperature with white bread cubes, where I can see how golden the fried result is. I fry the food before the colour becomes deep caramel. After 3 uses I discard it, because a) the taste changes b) the oil has a deeper colour. I never use oils that are processed industrially for frying, rather I choose the oils that I use because their properties already contain elements that tolerate higher temperatures anyway. I learned the mix of oils from the owner of a very high class deli in Milan, and it's always worked for me.

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Old 12-17-2016, 06:56 PM   #15
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Until just before you don't feel comfortable using it again.

There is no specific answer Kenny1999. As you will have noted there are just too many things that will affect the oil. Only you can tell how it goes.

I tried and I did some deep frying. When the oil was re-used again together with the addition of some new oil, for the second time, it became quite smelly, .
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Old 12-17-2016, 10:16 PM   #16
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Kenny, then there are those of us like me, who have been cooking for several decades and have never deep fried anything! It's true, I've never deep fried anything and have eaten very well over the years. Although I often enjoy deep fried fresh fish, I'd much rather someone else cook it for me.
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Old 12-17-2016, 11:27 PM   #17
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I tried and I did some deep frying. When the oil was re-used again together with the addition of some new oil, for the second time, it became quite smelly, .
Was it canola oil? That stuff will stink to high heaven if overheated. Restaurant grade canola for fryers is treated not to do this.
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Old 12-17-2016, 11:29 PM   #18
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Kenny, then there are those of us like me, who have been cooking for several decades and have never deep fried anything! It's true, I've never deep fried anything and have eaten very well over the years. Although I often enjoy deep fried fresh fish, I'd much rather someone else cook it for me.
I rarely fry anything in my house. I hate that heavy lingering greasy smell (I don't have good venting in my kitchen).

My mom loved seafood but refused to cook it inside the house because of the lingering smell, especially fish.
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Old 12-18-2016, 12:32 AM   #19
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I rarely fry anything in my house. I hate that heavy lingering greasy smell (I don't have good venting in my kitchen).

My mom loved seafood but refused to cook it inside the house because of the lingering smell, especially fish.
Same here. I have deep-fried food before, but like the others - I'd rather have other people do it for me. It's just not worth the effort to do it at home, imo.

I'm sure if I bought an electric fryer, it would work fine, but it's not that important to me.
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Old 12-18-2016, 12:46 AM   #20
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Should cooking oil be reused after deep frying, any health concern??

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Same here. I have deep-fried food before, but like the others - I'd rather have other people do it for me. It's just not worth the effort to do it at home, imo.

I'm sure if I bought an electric fryer, it would work fine, but it's not that important to me.

Agree. Like baking, I CAN deep fry, but I don't like to. Dairy Queen does it much better, and I don't have to deal with the smell or the hassle.

I see no problem reusing your oil a few times.
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