Reusing deep frying oil? What are "the rules"?

Question

I looked for a thread on this topic, but was unable to find one. What are the rules of thumb for saving and reusing deep frying oil? I don't remember the source, but I read once... from a source I apparently trusted... that if oil was used to deep fry protein (i.e., fish, chicken, turkey, chicken fried steak, etc.) it shouldn't be resused. However, if used on non-proteins (potatoes, tortilla chips, tempura veggies, etc.) it can be reused.

That "rule of thumb" makes deep frying turkeys a significantly more expensive proposition, given the price of peanut oil these days. A friend recently told me he has used the same oil for frying his last five turkeys, or so... apparently without any degradation in the quality of the finished product. Given the infrequency of turkey frying occasions, I can't believe the oil didn't go rancid on its own over this length of time.

Can anyone help de-confuse me? How can one determine when the oil is spent, past its prime, or gone rancid? What rules do restaurants use? I would hate to have friends over for deep fried turkey only to find the bird to be "off tasting" after all the preparation, drama and fanfare!

Answer

I asked a similar question a few weeks ago. Here's that thread:

http://chowhound.chow.com/topics/664894

Answer

If restaurants actually test it (they should, but not many do) there is a free kit that the fry oil companies give out for free, to show you that oil will be a lot darker than you think before you should dispose. A glass eyedropper to suck it up and a few different tubes of used oil at different stages. I always think mine is a goner because it looks so dark. but when you actually compare there's still a long way to go. The ultimate sign is if it foams up when you put something in the hot oil: then it is well past its prime and you shouldn't use. But that doesn't mean it will make you sick or anything, just that it will taste sort of burnt.

As far as meat and non-meat in the same fryer, they do that all day long at almost any restaurant you can name. Places that are really picky will dedicate certain fryers for fish, and maybe meat in another, or just french fries if that's an important item to them. Any off tastes occur due to not straining the oil of the debris in the bottom (which comes from breaded foods mostly). It doesn't go bad on its own, just from overuse really. I've seen solid shortening (like Crisco) go rancid, but not liquid.

Answer

The only thing I ever deep fry is turkey at Thanksgiving. I might strain it through a coffee filter in a funnel and use it once more, but I sure won't use it repeatedly. I think trans fats may form over time, for one thing. You're right, though, I use peanut oil and it is pricey to toss it each time.

Here's a short article I googled up:

http://www.associatedcontent.com/article/1343555/is_it_safe_to_strain_and_reuse_deep_pg2_pg2.html?cat=22

Answer

I saw Alton Brown frying a turkey on Good Eats over this past weekend; he said that the oil is good for one more use after the turkey. I've worked in restaurants for years and I can tell you that most use the oil until they can't use it anymore and it's mixed with everything: chicken, fish, breaded veggies, and even donuts at one place I worked in.

At my most recent job, they change the oil a couple times per week depending on how how much use the fryers get, but they filter it several times during a shift and at the end of the night.

With that said, why shouldn't we re-use oil at home? It has to be cleaner than any restaurant, right? I cook my chicken and pork with the same oil and strain it after use. I cook my potatoes or veggies in separate oil and the same with fish. I don't mix any of them and store separate. I use them a few times each and discard before it turns brown.

Answer

Oils like canola or peanut oil, or even soy ("vegetable oil") don't go bad with a single use. I can't see reusing oil over 5 Thanksgivings, but 5 uses over a few weeks or a couple of months has not been a problem for me. Oil degrades gradually, so my rule of thumb is: toss it when it starts to give bad results. At some point the oil will begin to impart a burnt taste to whatever you fry, but about the only thing that really effects the flavor is fish. As others have noted, filtering after every use is very important (I use a fine sieve -- don't have the patience to use a coffee filter).

And since we're approaching Thanksgiving let me rant a bit. Don't waste your money on peanut oil if you're going to toss it after one use! I have no idea why so many web sites and recipes that come with turkey frying kits call for peanut oil, but any cooking oil will do. It's not as if you're heating the oil to it's smoke point or the oil imparts some flavor to the bird. If you're going to use it and lose it, buy whatever is on sale.

Answer

I have a deep fryer that sits on my coutertop because it gets a great deal of use. I always buy Kroger Brand peanut oil and it costs about 9-11 per gallon.

My oil is now starting to get dark, but I have been using it for probably 2 months. Maybe a bit longer. It still fry's chicken wings, chicken tenders, chicken breasts, fries, jalapeno poppers and such with no problem what so ever. 

I try to remember to run the oil thru a paper towel or sieve after frying things like chicken tenders and wings just due to the egg wash/flour mixture that I usually use, but I rarely clean the oil after something like fries. 

So, like I said, I have had no issues using my oil for prolonged periods of time. I use it once or twice a week, so there have probably been at least 15 uses, and maybe more. Also, I agree with the fomaing statement. So long as it's not foaming up on you, I'd say you're good to go.

Answer

here's a funny story, probably happens to people all the time. When my kids were preteen, we made homeade potato chips ALL THE TIME. Their friends would come over and we'd go through pounds of potatoes. Anyway, I used to keep a bottle of used oil right by the stove all winter (that was when we did it the most) Anyway, one day my daughter wanted to make brownies and ...you guessed it, used the frying oil next to the stove instead of the fresh stuff. Everyone loved the brownies, even if they did taste "off". Needless to say, the cooking bug for her has NOT bitten!

Answer

America's Test Kitchen did a comparison between used fryer oil stored for a month in the freezer, at room temp., and in the fridge. They felt that hands-down the freezer oil was fresher than the other two. I've started freezing my oil in a labeled freezer bag for future deep-frying, or taking a little out for small fry jobs. It feels so much better not throwing it all away. 

I don't save oil that smells strongly of the foods cooked in it. I'd rather not take the chance of ruining the new dish.

As hvnbndw suggested upthread, though, it's probably best to let it come to room temperature before heating a large quantity.

Answer

"What are "the rules"? "

smell it? does it have a rancid smell to it?
don't mix savory with sweet meaning if you used it for doughnuts, don't now use it for deep frying bacon wrapped shrimp and really pay attention to vice versa.
sieve through it and make sure no old particles are in the bottom of your fryer

Answer

while you are testing the rules, i'd urge you to try this item which i think is brilliant (and so says the cardiologist coalition): chicken-fried bacon strips. http://theeatenpath.com/wordpress/wp-content/uploads/2009/03/sodolaks_country_inn_chicken_fried_bacon_01.jpg
from sodolak's country inn in snook, texas http://theeatenpath.com/2009/03/23/chicken-fried-bacon-sodolaks-country-inn-snook-tx/

Answer

There was a cookbook I once had that came with a West Bend Electric Wok (remember those?). The author suggested frying a cut piece of ginger and a scallion or two in the oil for a couple of minutes after it came up to temperature to counteract any 'old oil' tastes and smells. Works like a charm. I even toss a set in before the oil cools down for good measure.

My oil gets reused probably a half dozen times before it gets tossed, plus I'm aware it breaks down in the heat into saturated fats, so I watch the temps closely. I'll plan a seafood night for its last run, like fish and shrimp tempura, before it goes into the trash.

But the CI freezer method sounds great, gotta try that one! The reason for my recycling oil after only 5 or 6 times is mainly due to not deep frying that often. If it could keep without any concerns about going rancid, I'd let it hang around much longer.

(I looked at a can of Crisco at the store last night, over $6 a can, and it's not even a full 3 lb. any longer! I only needed it for some dough, so I bought a pound of lard for a buck fifty instead.)

Answer

I have a small deep fryer. The directions say to strain the oil after use in cheesecloth or a strainer to remove the residue. Put a lid on the tub of oil. When the oil gets frothy, really dark or has an off smell about it -- discard it.

Answer

Saw this on a state extension site:

ANSWER - What is the proper food safty for the handling of deep fat frying oil? Allow the used oil to cool completely before pouring it into containers for refrigerator or freezer storage. 

Does it need to be strained? Straining removes the large food particles and prevents charring of them during subsequent frying. Removal of food particles also removes food so bacteria won't grow. 

Can it be reused? Yes. You can refrigerate or freeze used oil for no more than one month. (According to USDA Meat and Poultry Hotline) 
Don't reuse the oil if foaming occurs during heating, changes color (darkens or lightens) during heating or acquires an off/odd odor. 

Does it need to be refrigerated? Yes. Keep in mind that oil and bacon can produce an anaerobic environment that could allow for Clostridium botulinum growth. Refrigeration will slow bacterial growth. 

If a consumer makes a blooming onion in some hot oil can that oil be left out at room temperature for 1 or 2 days and then reused? NO. Leaving it out for 1-2 days is not recommended. Bacteria can grow on the food particles at room temperature. Therefore, strain and refrigerate after cooling.

Answer

I reuse oil until it smells bad. I don't go by colour because, let me be frank here, I use a LOT of spices in my savouries when I deep fry, so the colour of the oil changes a LOT. 

If I'm deep frying something sweet, I won't use oil that's been used for a savoury - it just tastes wrong. But I will use oil that's been used on a sweet to fry a savoury - that hasn't negatively impacted flavour yet. 

Depending on what I fry, I might use the oil half a dozen or a dozen times, maybe more. But I definitely smell it before I use it. And I filter it after every use.

Answer

To answer the oil question, USE your nose and common sense. 

I use Peanut Oil 99% of the time for frying. When I fry up potatos/Hush Puppies & fish...fries FIRST then the Hush Puppies and lastly the fish, no transfer of fish flavor to the fries or hush puppies.
THEN I sometimes strain my oil, sometimes I dont bother, any "bits" will settle to the bottom of the oil storage container in a short time...just POUR oil from container when next used SLOWLY & stop before the settled "bits" pour out.

Ive never put used Peanut oil in thr freezer or fridge, stays in my pantry. How LONG will the oil keep, how many times to reuse it? I reuse my oil half a dozen or so times up to 6 months or so, with perfectly good tasting results....ONCE Ive fried fish in the oil, I ONLY reuse THAT oil for frying fish, NOT anything else, I keep two batches of "re-cycled" oil...one batch for most everything BUT fish...I dont care for fish flavored chicken or Okra personally.

 USE your nose and common sense as far as how LONG you reuse your oil...IF it smells clean, looks clean, it PROBABLY is. For me, I just think the oil starts to impart an "oil" flavor into the fish/food after half a dozen times of use or after 6 months or so & it's time for it to go.
Ive always figured that 375° kills any little bugs.

I'm a born & raised Texan, pure Southern, huntin' & fishin', beef eatin' country boy, now on the north side of 60, and Ive been cooking for a LONG time, and I must admit, I am AMAZED at some of the things I read and hear about what is "safe" and "not safe".

I reckon a lot of us Baby Boomers are just darn plain lucky to be alive today(!!) IF you listen (believe) the FDA or people who actually believe what the FDA has to say.

Today, IF someone leaves a slice of Bologna out on the counter for 6-8 hours and it becomes room temp, people treat it as if it is carrying the Black Plague, geez!
I have NO clue as to the number of Bolgna sandwiches I ate at school from a Lone Ranger or Superman metal lunch box that had sat beside my little desk ALL day, made at least 6-8 hours earlier that morning by my Mom...I must have had angels on my shoulders not to have died or ever gotten ill from one of those sandwiches...of course I did "trade" a lot, never liked Bologna..:)...but my firends in barter never died either from one of those warm Bolgna sandwiches....I guess as for more proof of my Guardian Angels...my school lunchtime was never better than when I opened up my Lone Ranger lunch box & found leftover fried chicken(!)..just shows the Lord was with me I reckon...boy, just never new how close us Baby Boomers came to being extinct...I ran with scizzors and have two perfectly good eyes despite numerous BB guns, how lucky can one man be! 

My Mom saved ALL bacon grease in a metal container that was MANUFACTURED for that purpose, sat on or beside the stove, had a strainer top to remove the "bits"...the container never saw the inside of a fridge, and IF I recall rightly, ONLY the outside and the strainer portion was EVER cleaned...I suspect because it never was empty..."empty" would have been a catstrophe...would have meant no teaspoon of bacon grease in the green beans, blackeyed peas etc etc.

Today, people seem to be afraid of everything because the Government SAYS so!? Really? Happy with the IRS and DMV too are you?

The FDA is a bunch of suits & ties that sit behind a desk as a JOB, they dont stand in front of a stove and cook.
The FDA has CHANGED the "safe" internal temps on pork/lamb/poultry and dozens of other foods over the last several years..."changed" as in LOWERED the "safe" internal temp. The suits finally figured out you dont have to cook a bird or pork until its drier than the desert, decided it was "safe" to eat while it still resembled what went INTO the oven or on the grill.

Sorry, I'll continue to use common sense when deciding IF "something" is safe...and my nose too, niether have ever let me down in over 60 years...I can NOT say that about the Government.

Have someone over today and break bread, eat, and be happy...skeeter69

Answer

My wife and I had a restaurant in California and we deep fried chicken and French Fries every day (With Solid Boxed Lard)....we changed the fryers every week and totally cleaned them professionally....My wife would take some back to our house and strain it using a cut from her pantie hose and keep it at room temp and she'd add bacon when she deep fried at home and reused it.....we never cooked fish in our fryers at the restaurant cause Cowboys didn't eat Fish...We never put used oil in the fridge and everyone in our family survived and still does to this day....when cooking oil is turning you will tell by the color....it turns really dark....pitch it out

Answer

The key to frying oil life is the viscosity. All cooking oils lose their viscosity with heating and cooking. You do not bring home a new bottle of oil and store it in the fridge or freezer; you should keep it in a cool, dark cupboard. If you do not overheat it, strain it well after use and store it in a dark glass container in a cupboard or cabinet you can always get 5-6 uses out of peanut oil. Vegetable oils and shortenings have lower viscosity and will not last as long. I rarely deep fry fish or seafood, but when I do I use new, lighter oil and keep it in a separate jar for shorter periods of time before disposal.

Answer

I am 72 years old and have been deep frying for many years. 

The rule of thumb for reusing oil is color and taste. 

The oil should be relatively clear and taste bland.

After you have finished deep frying, let the oil cool down, filter it and store it in a closed stainless steel container in the refrigerator. 

 My deep fryer has temperature control settings and I normally set them between 340° and 350°.

It also has a light that comes on when the oil has reached the proper temperature.

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