On used cooking oil | By Umbra Fisk | Grist | Ask Umbra

On used cooking oil

26 Nov 2007

Got questions about the environment? Ask Umbra.

Dear Umbra,

It's always nice to look through cookbooks and to watch cooking shows that feature yummy deep-fried food, and I have often been tempted to try and cook my own creations. However, no one ever seems to mention what they do with the used cooking oil, especially after deep-frying. What is the best way of disposing the oil? I do not want to tip it down the sink, and adding it to compost will suffocate the earthworms. Perhaps it's better all round not to deep-fry anything?

Liz
Atherton, Australia

Dearest Liz,

Over here in America, people deep-fry entire turkeys for the late-November Thanksgiving holiday. We believe anything can be deep-fried. Recent years have seen various deep-fried candy bars appear at country fairs, and I think one can deep-fry ice cream. These occasional revolting yet compelling treats -- and our obesity epidemic -- aside, deep-frying is a tasty, time-honored cooking technique. Do not eschew it afore you even do it.

Grease frightening.

Photo: misterbisson

You are correct, though, the leftover oil should not be poured down the sink drain. It will create an ungodly mess, clog the drain, and run up your plumbing bill. Any grease that makes it through to the sewer must be treated at the wastewater plant, and they don't want to deal with your grease. If you have a septic tank, it'll just help shorten the life of the tank.

Cooking oil can be reused, although it degrades with each use and will eventually need to be disposed of. To reuse it, filter it through a fine sieve or layers of cheesecloth to remove food bits, then store it in a closed container in a cool, dark place. Apparently you'll know when it's too old or degraded, because it will appear dark and viscous, and smoke when it reaches 190 degrees F or lower. The "dark" aspect seems unmistakable, as would out-and-out rancidity, and I think after putting in some practice you'll recognize an oil that smokes before it should.

Ask Umbra continues below

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When the oil's time has come, you may just need to call your local garbage folks (your city or province) and ask what the rules are about used cooking oil. In the U.S. I've found that municipalities differ as to their preferred technique. A Maryland county directs people to bring large amounts to the transfer station instead of leaving it with curbside pickup. In parts of Alaska, folks can put only a gallon in the trash at a time; one suggestion for those with a larger amount was to find a pet-food manufacturer who needed used oil. Who knows what for -- better not to ask. A Washington county suggested mixing large amounts of oil with cat litter or sawdust to make a solid, putting it all in a tightly sealed container and only then putting it in the trash.

You see what I mean -- each locality seems to have a different preference. I think containers of oil exploding in trash trucks may be one issue, and another might be how oil behaves in a landfill or incinerator. I direct you to your local trash informants because I think they will have an opinion, not because I'm passing the buck. If they have no opinion, let your oil solidify, and/or mix it with sawdust, wrap it up tightly, and place a gallon or less per week in the trash. Enjoy your cooking adventures.

Tempuraly,
Umbra

Yours is to wonder why, hers is to answer (or try). Please send Umbra any nagging question pertaining to the environment -- but first check out her FAQs!

The claims made in this column may not reflect the views of this magazine. Neither the magazine nor the author guarantees that any advice contained in this column is wise or safe. Please use this column at your own risk.

Umbra Fisk is Grist Research Associate II, Hardcover and Periodicals Unit, floors 2B-4B.

Comments: (12 comments)

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Veggie Oil Recycling

While few cities offer waste veggie oil pickup (like San Francisco.. http://www.sfgreasecycle.org/ ) there are a growing amount of Biodiesel and waste oil coops organizing around the country. You can find places to fill up your old diesel that has been converted to use WVO (waste Veggie Oil) at http://www.fillup4free.com/

by timothyb at 10:30 AM on 26 Nov 2007

reuse before recycle

Definitely reuse before dumping it. I keep frying oil in a jar (labeled "sweet-safe" or "not sweet-safe") in the refrigerator. I then use it as cooking oil for other purposes, frying and otherwise, like banana bread (if it was donut-frying oil) or sauteeing. It takes a long time to use it up, but then again, that tends to limit how much fried food you make... not a bad thing, right? I've never had to actually throw any out because it was too old, and I've had used frying oil in the fridge for at least a year at a time.

by mihan at 11:30 AM on 26 Nov 2007

biodiesel

it shouldn't be too hard to find someone in your area who's making biodiesel, and they'll almost always want it. that's what i do.

by laurenmcnees at 3:02 PM on 26 Nov 2007

yuck

Since it's unhealthy in the first place & also hard to dispose of, why don't people just cut back on frying stuff or stop frying all together? I haven't fried anything at home in at least 10 years and my cholesterol, waistline and garbage dumps are better off for it.

by eram at 6:46 AM on 27 Nov 2007

used frying oil

What happens when you just pour it into your composter?

by bailsout at 1:36 PM on 27 Nov 2007

Used frying oil

Pour the oil around the base of your rosebushes.
It will quickly absorb into a soft mulched soil.
When you come back (two weeks) to turn the soil you will find it completely broken down and a increase in the worm population. Your garden should be able to support the amount of cooking oil used in the average home.

by bareman2 at 3:51 PM on 27 Nov 2007

recycling centers

Near Philadelphia where I live is a recycling center, and there is always one or two people parked there on recycling days, receiving oil for their funky-looking cars. Somebody wants your samosa oil (that's how I end up with oil)!

by MaggieB at 6:09 AM on 28 Nov 2007

Downcycling used cooking oil

From my experience, I know that some restaurants in London generating considerable amount of used cooking oil (minimum of 80 litres) get paid to have it collected. The price fluctuates due to demand and supply, therefore it will be variable.

by nicosauvage at 7:04 AM on 28 Nov 2007

Biodeisel

You could do what my son does. He works in a restaurant where they dump their deep frier grease ever night. He's got a VW deisel, so he just filters it and converts to biodeisel. His eshaust smells like french fries. Most people don't know that Rudolph Deisel designed his engine to run on vegetable oil, not petroleum.

by Vladilyich at 3:16 PM on 29 Nov 2007

Pass it on

I, too, was thinking that you could ask a local fast-food or chinese restaurant is you could add it to their waste oil. They probably wouldn't object for small amounts or if they are selling it(or giving it away) to WVOilers.

NoPunProductions.com ~ AmericaTheGreen.org

by Greta at 1:38 PM on 30 Nov 2007

Reuse, then Recycle

eram: When properly done, frying is plenty healthy. By properly maintaining the oil temperature and not overcooking, steam pressure from within the food keeps the oil on the outside, so very little oil actually gets into the target food. Besides, blood serum cholesterol levels have been more clearly linked to saturated fats (like butter) and trans fats (shortening); veggie oils commonly used in home frying are far more heart-friendly.

Before disposing, I'd suggest reusing first. If you've been managing your oil temperature correctly, you should be able to strain, store, and reuse the oil several times before it gets funky. Signs that the oil is past its prime are funny flavors and odors, an unusually dark color (meaning lots of dissolved solids), and especially smoke. Once oil heats beyond its smoke point, it breaks down chemically, and that doesn't taste very good.

As for disposal, there's somebody in any decent-sized city who collects and reuses fry oil. Call your recycling center for leads. Giving it to local restaurants sounds like a good idea, but I doubt they'd accept it, because of either health code restrictions or the potential liability of accepting deliveries from strangers.

[As nicksauvage stated, restaurants often do get paid for their used oil. Processors can filter it and use it in biodiesel or cosmetics.]

-- A.

Taking accounting to the extreme since 2004.

by akbeancounter at 10:39 AM on 11 Dec 2007

Fry, Fry Again

In Riverside, CA the city has been collecting it. The sewage treatment plant then converts it to methane and uses it for its energy needs!

by 2349 at 4:54 PM on 25 Dec 2007

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