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

[DigitalVelvet]

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!

[meatn3]

I have never deep fried turkey. I deep fry very seldom, so I do reuse the oil.

After my oil has cooled I filter it (coffee filter or cheese cloth), bottle it and put it in the fridge.

Each time you use the oil it will darken - I only let it get a few shades darker, ie reuse 2-3 times max. I do not use oil from fried fish when frying anything else in order to avoid transfer of flavors.

If the oil is bad it will be apparent with a quick sniff test or a taste.

If you want to get rid of a quantity of used oil, post on craigslist or freecycle - there are many people making their own bio-diesel who will be thrilled to pick it up!

[hvnbndw]

The problem with refrigerating oil is when to use it. My mom put a saucepan full of oil on the stove straight from the fridge and as it heated it went up like an automic bomb onto the ceiling. No one got hurt but soooo dangerous! It must be left out till room temperature when using large quantities that are cold.

[cheesemaestro]

I asked a similar question a few weeks ago. Here's that thread:

http://chowhound.chow.com/topics/664894

[coll]

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.

[scubadoo97]

I go more by smell than color.

[mcf]

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/arti...

[coll]

I think (too lazy to look up) trans fats are put there when the oil is processed, they don't "form over time". Where I live it's against the law to use any oil with transfats anyway, and it's funny how I don't obsess about them anymore, I almost forgot about all the controversy......but anyway peanut oil isn't processed like commercial fry oil and I don't think there are any concerns with transfats there. Feel free to refute though.

[mcf]

Trans fats are formed in some oils by hydrogenation, some natural transfats occur in smaller amounts naturally, but heating causes changes in the oil and undesirable compounds to form also.

So yes, you can create less healthful oil over time with re-use.

[Cherylptw]

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.

[Zeldog]

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.

[alkapal]

i think peanut oil makes a tastier fried turkey. and i definitely wouldn't toss it after one use.
meatn3, i agree with you.

and i'm *pretty darn certain" than peanut oil is not nor will become a "transfat" from use.

[hpman247]

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.

[alkapal]

sound advice, hpman247.

[momoftwo]

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!

[coll]

When I was a kid, my mother always saved the Crisco from her fried chicken, but my friend and I didn't realize what it was and we cooked up some donuts with it. To this day, she recalls our "Chicken Donuts", yes the flavor was that strong.

[DigitalVelvet]

Hey.... if they can have chicken-n-waffles in some of these neo-soul food places, why can't you have Chicken Donuts?!? ;)

[alkapal]

scuzzo will put those babies on his wafflemaker.

[16crab]

I was going to post the same question, but specifically to Crisco. I'm on a quest to perfect my homemade donuts and everything I'm reading says use Crisco. So the trans fat thing aside...my question is, I can strain it, put it back in the can, and then should I store it in the fridge or at room temperature? Either way it's going to go from solid to liquid back to solid, over and over again. Is that ok? I seem to remember my mother doing this, but since she's not around anymore to ask...

[coll]

Store at room temp. And they do make a non trans fat Crisco nowadays. I grew up eating Crisco used over and over, and I'm fine so far, not that that's scientific proof. But who knows if it had transfats in it then anyway? I think hydrolizing fats is something that started in the 70s? (OK I will look this one up)

OK was I wrong. Trans fats were discovered/invented at the turn of last century, and one of the first ones to jump on it were the makers of Crisco, in 1911. Wonder if anyone's sued them yet for their unhealthy shortening.

[terrierboy]

I don't fry foods too often, but the latest studies I've read warn against reusing oils because of the changes they undergo during high heating, primarily linked to oxidation. The general consensus leans toward safflower oil as one of the healthiest choices; I've also had success with avocado and grapeseed oils. We usually used peanut oil when I was a kid; I haven't found anything negative about that one yet.

[coll]

Once I run out of the 3 big jugs of MelFry (trans fat free!) in the garage, I'm going peanut.

[alkapal]

you can re-use it a few times before the oil is "exhausted." single-use deep-frying oil is very unthrifty and not necessary. for deep frying, i'm always a peanut oil gal.

[cgarner]

Growing up, I had a friend whose mother made the absolute best fried chicken. When I got older, I asked her how to make it, she wrote down all the ingredients and the steps.

I recreated exactly as she had and it just didn’t turn out right. I brought a few pieces over to her and asked what I did wrong.

“you used new grease”
What?
Mrs. Roane always saved grease/oil/fat from frying and that’s what she used to make her fried chicken.

I never have had the gumption to save all the greases from frying to try to re-create the recipe using used fats…

[coll]

There is such a difference between brand new oil and used. There is something to be said for each.

[cgarner]

I am considering taking the bacon fat that I have in the fridge and trying again one day, with crisco and bacon fat...I watched one of the food shows, a chef threw bacon into the grease before starting the chicken (higher end restaurant doing fried chicken, show on the cooking channel United Tastes of America I think)
I feel it's akin to mimicking the flavor of the reused fat that Mrs. Roane used in her fried chicken

[coll]

That sounds interesting. My Mom always fried in Crisco, not that it was her specialty. And always put it back in the can til it got really dark. Just a few spoonfuls of bacon fat would probably be amazing.

[alkapal]

best fried chicken i've had is from a friend in alabama, and she uses crisco in a skillet -- not "deep" fried.

[coll]

That's what I used to do too, with liquid Crisco. It really was the best. 10 minutes each side.

[bear]

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.

[alkapal]

fish fry oil has to be kept for fish -- or of course the hushpuppies that go with the fish.
;-)).

i wanted to mention that a famous southern lady's fried chicken (sold commercially in her restaurant) was cooked in a huge skillet with lots of oil and sliced onions to flavor the oil. saw it on a cooking show…maybe tyler florence's "ultimate" series (which was very well done).

[bear]

Oh, right. I remember that episode. I think she worked in an inn. I bet that's some tasty chicken. And, I agree, that was a good show.

I wonder what Tyler is up to these days. I liked the show because the recipes weren't fussy, but they had lots of flavor.

[alkapal]

i liked the show very much because he was genuinely interested in finding the best folks to learn from, and the travels were nice…and the ultimate recipe always looked tremendous. and i think you are right -- it was an inn. i can still picture her and that huge pan of oil. she had a sister. was it in maryland? or south carolina?

[terrierboy]

I had the recipe bookmarked. It was the Chalfonte Hotel in Cape May, NJ. We tried the recipe, though I have to use gluten free flour, and we used Old Bay instead of the paprika. The onions imparted a marvelous undertone of flavor in the chicken. Yum! I can still taste it. I do miss that travel phase of Tyler's Ultimate. That was a good show. It's always wonderful to see the origins of foods. FN seems to have Tyler focusing more upon the Food Truck race show these days.

[alkapal]

YES!!!! Cape May! good job, terrier boy!

here is the recipe link: http://www.foodnetwork.com/recipes/tylers-ultimate/chalfonte-fried-chicken-recipe/index.html

here is a link to the inn, and the "magnolia room" dining room. http://www.chalfonte.com/dining.html

boy that looks like it'd be a neat place to visit.

[cgarner]

we vacation in that neck of the woods for a week every summer, and make frequent visits to Cape May for weekend jaunts, and I never knew about this place (though there are so many little b&b's in Cape May and some good dining options too)
I will definately have to try the Chalfonte this summer

[NVJims]

The biggest problem with the cold oil is the chance of it having moisture. ANY moisture in the pot while it is heating up may cause a bleve with potentially deadly results. Slow rewarming with a solid cover will help remove the moisture.

[iL Divo]

"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

[alkapal]

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/ch...

[RelishPDX]

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.)

[cgarner]

lard tastes better anyway!~
;-)