Proper disposal of used cooking oil/fat/grease

[johnnyd]

I decided one day to add a squirt of dish washing liquid and hot water to the leftover oil and make a big froth before dumping down the drain, thinking it would dissolve better in sewage pipes.

But since I started hanging around this joint, I've been saving oils and fats whenever I can, and dispose only in the trash. I've learned lamb fat shelf-life can be measured in mere hours.

[cbread]

If it's relatively clean beef fat or chicken fat from stock-making, I'm likely to filter and freeze it for future use.

←

Can anyone recommend the best ways to filter oils and fats? Currently I just stockpile the stuff, en mass, in the freezer, in a coffee can, for eventual disposal at the dump. I'd like to separate the nasty from the reusable, and clean up the worthier oils for reuse, but I don't know the best way to do that.

[Hest88]

I throw a wad of paper towels into the trash can, to protect the plastic garbage bag from the hot grease, and pour the grease straight into the trash.

[steverino]

I used some canola oil a few weeks back to fry some taters and chicken- y'all think it's safe to fire up again? Obviously it's going to be brought up to temp high enough to kill any bugs... I smelled it, and it seems ok.. any input would be appreciated.

[Chris Amirault]

I always have several quarts of used fry oil in the basement, never refrigerated. We're all still here.

[ermintrude]

Yes

If the oil was kept in a cool place then should have no problems. The biggest problems I've had with oil is it picking up flavors from previously fried things.

If you fried spiced chicken then perhaps not the thing to fry a delicate fish in batter or if the oil is oxidized - you can smell it, safe but YUK.

[rooftop1000]

And... if you overheat Canola oil it can start to smell like bad fish

tracey

[dougal]

Its stored unrefrigerated in stores (and without any protective atmosphere in the top of the bottle).

There are no warnings on labels about "once opened, keep refrigerated and use within x days".

It should be fine.

Storing out of strong sunlight (and cool and in reasonably full bottles) should help to delay the stuff going rancid. (But that takes many months, not weeks.)

In use, its overheating/burning the oil that risks spoilage.

If it smells of what you cooked last, that's not a disaster.

But if it smells rancid, or the oil itself has darkened dramatically, its time to change it.

In which case, try and find a recycling facility.

Its bad to tip it down the drain.

Carefully decanting the oil should leave behind lots of bits that have settled to the bottom. (Don't be too greedy about maximising the yield of clean oil. Cleaner oil is better than more oil.)

Then filtering off as much of the remaining detritus is desirable. It'll filter faster if its warm. (But 'hot' gets dangerous!)

It always used to be advocated to fry some potato (or bread) to try and remove old flavours. Personally, I think removing flavoured solids is more important.

[Raoul Duke]

For my used oil I deep fry some fresh ginger to leech off any residuals that can alter the taste/smell of the oil. Heard it/read it somewhere and it seems to work or I'm still stoned.

[maggiethecat]

It should be just fine. Here's a horror story from someone who once worked at the "deli" of our local Target. (That's another story, and a good one...)

The Target fryer contained a couple of gallons of canola. It stayed at 350 ten hours a day, frying chicken and potatoes. It was left to sit for more than a week -- by Friday it was black. A new batch went through the rotation: doughnuts, then chicken, then potatoes then fish then shrimp then scallops. It was filtered once a week. Nobody died.

[Chris Amirault]

No people, but the concept of edible food was pronounced dead on the spot.

[FjornF]

To expand on what Chris said, some soap is good, too much soap is bad (allows to much oil to penetrate through the food making it greasy). Interestingly alot of Donut Shops do not worry about over saponification because they are continuously adding more fat the replace that which was been absorbed by their baked goodies.

Joe Pastry on the subject

I think there is not yet a consensus on if reusing oil is healthy. Does anyone have good information on this? From the article about soybean oil:

"Whether at home or in a restaurant, one should not reuse oils that are highly unsaturated and contain linoleic acid because they form HNE and related compounds," says Csallany. "Perhaps the best advice in general is to eat only limited quantities of fried foods."

Interesting, sounds like another compelling reason to switch back to animal fats. Ill take it.

[John Rosevear]

Later, Parsons suggests about 1 T old oil per cup of fresh oil. I just dump a glug of old oil into the fryer/dutch oven before adding the new stuff. It really works: the difference in crispness in particular is remarkable.

Seconded. And while I'm not sure the science actually holds for this, I have noticed that if I don't have used fry oil handy, a glug of bacon grease in the fresh (I use corn or peanut) oil seems to do the job.

[eternal]

I reuse oil. I have a gallon of peanut oil that I would fry anything but stuff from the sea in. After I'm done, I strain it and freeze it. Still smells fine. When it gets to the point that it doesn't smell good, I would throw it out and start over. For the home cook, tossing a gallon of peanut oil every time I used it would make frying too expensive. If restaurants can use oil 100 times a day for a week, I don't see why I can't use it once every 3-4 weeks for 6 months...

[IndyRob]

Someone on another site recommended the T-Fal Ultimate EZ Clean Pro Fryer. It appears to be unique in that it will automatically (?) filter the oil after use and then you can easily break it down and throw everything but the heating element into the dishwasher. Anyone have any experience with these?

http://www.t-falusa.com/All+Products/Cooking+Appliances/Deep+Fryers/Products/Ultimate+EZ+Clean+Pro+Fryer/Ultimate+EZ+Clean+Pro.htm

[Chris Amirault]

Funny this should bump up. I fried about 10 lbs of potato, sweet potato, taro, and other root chips for a New Years party and then bottled up the oil the next day. Last week, I sniffed it and it seemed completely neutral, so I just used the entire bottle, adding only a bit of fresh oil to top it off. The 10 lbs of curried chicken I then fried was among the best I've ever had -- and, again, had that shattering crust you die for. The oil now is spent, I think, and tastes of the curry powder and chicken.

(BTW, I don't always prepare 10 lbs of food at a time. Just sayin'.)

[mgaretz]

Someone on another site recommended the T-Fal Ultimate EZ Clean Pro Fryer. It appears to be unique in that it will automatically (?) filter the oil after use and then you can easily break it down and throw everything but the heating element into the dishwasher. Anyone have any experience with these?

http://www.t-falusa.com/All+Products/Cooking+Appliances/Deep+Fryers/Products/Ultimate+EZ+Clean+Pro+Fryer/Ultimate+EZ+Clean+Pro.htm

I have the "Emeril's" version of this fryer and I love it. Once the oil has cooled it automatically drains and filters into it's storage container. I put that in the fridge and reuse the oil 10-15 times (I don't fry any fish) topping up with fresh oil when necessary. We don't deep-fry all that often so the oil can be in the fridge for months between uses. So far no problems at all.

[jsmeeker]

Timely topic for me, too.

Last weekend, I wanted some Buffalo wings to eat while watching football. I bought a gallon of peanut oil and used about 2/3 of it to fry up with wings. I strained it into another container and put it in the fridge. On Thursday, I used that oil to make some potato chips. Last night, I used the oil to make fried catfish and hush puppies. Everything was really fantastic on the second and third fry session. I think the potato chips were the best I had ever made. And the fish and hush puppies turned out great.

I strained out the oil from last night's session, though probably not as well as I could have. I should have used some cheesecloth in my fine double mesh strainer. This oil is back in the fridge. Can I use it again? I DID cook some fish in it, so should I only use it for fish again?

[judiu]

Timely topic for me, too.

Last weekend, I wanted some Buffalo wings to eat while watching football. I bought a gallon of peanut oil and used about 2/3 of it to fry up with wings. I strained it into another container and put it in the fridge. On Thursday, I used that oil to make some potato chips. Last night, I used the oil to make fried catfish and hush puppies. Everything was really fantastic on the second and third fry session. I think the potato chips were the best I had ever made. And the fish and hush puppies turned out great.

I strained out the oil from last night's session, though probably not as well as I could have. I should have used some cheesecloth in my fine double mesh strainer. This oil is back in the fridge. Can I use it again? I DID cook some fish in it, so should I only use it for fish again?

The nose knows...

[jsmeeker]

hmmm OK. I smell it and it smells like oil. But I am not really sure if it's a BAD smell. Sure, it doesn't smell like the stuff in the bottle that hasn't been used for anything, but I am not entirely clear what the standard is here. In the past, I frequently would use cooking oil once. But that gets expensive, especially when you use something like peanut oil.

[David A. Goldfarb]

I find that after I fry any kind of fish in oil, I need to replace the oil. Heat it up and make some French fries, and I bet they'll taste like catfish.

What I've been using for frying lately is a Griswold cast iron Deep Fat Fryer (#1003), and I've been really pleased with it. Fortunately these aren't particularly collectible, so you can find them on eBay for around $40 without the original basket or $60 with. The shape is just right, so there isn't excessive spatter with a half-full pot of oil, and the heat retention of cast iron helps maintain the temperature when the food is added to the oil, and it's not another appliance vying for counter space. I've been keeping it ready to go with beef fat in the fridge, and I filter the oil through a strainer lined with paper towel as needed.

Edited January 23, 2010 by David A. Goldfarb (log)

[nickrey]

After frying I always use a paper filter for my oil.

When opened up they are cone-shaped and fit into a large funnel sitting directly in the oil bottle.

It takes a while for the oil to run through but I find I can use the oil many times before replacing it.

Jeff, if your oil smells at all like fish, I wouldn't use it for anything other than fish and chips.

[agray]

This is indeed timely, especially the comments about possible issues with polyunsaturated oils and reuse, as I've been starting to research cooking with animal fat instead of vegetable oil. It's still early days (I'll be rendering lard next week), but here's what I read recently in Jennifer McLagan's "Fat":

Lard is very low in polyunsaturated fatty acids, so it is very stable when heated and much slower to oxidize and turn rancid than highly polyunsaturated oils are... all fat degrades with time, and heat makes this happen even faster. The fat should be filtered after each use, cooled and then refrigerated. It's probably not wise to reuse the fat more than three times.

Now this is lard she's referring to - I wouldn't likely refrigerate peanut oil etc, but from what I've been reading it seems that it might not be a great idea to keep vegetable oil around through many fryings due to the oxidation resulting from frying.

[Gail CDM]

With too many years in a restaurant...we only used our oil 3-5 times, depending on what you have cooked in your oil...before changing. With the right filter, you can recycle your oil to get more LIFE out of it.

Vegetable oil, a good one, is the best. It has the lowest smoke rate, and it cooks the cleanest.

Fishy smell is a good indication that you used cheap or your oil is burned (got too hot for the oil used.)

[nakji]

How many times can we re-use oil? I fry in peanut oil, then pour off what's left into a jar, which I keep in the fridge. When I fry, I pour the lot from the fridge into the wok, then top it up using fresh oil. Is this madness? No fishy odors have emerged yet.