Experiment: Purification of used cooking oil for reuse.

[Denninmi]

Just a little kitchen experiment I tried. I deep fried some calamari and fish yesterday, along with some french fries. Which is something I do VERY rarely, maybe a couple of times a year. The calamari were done in seasoned flour, the fish were done in batter, while the fries, I must admit, were commercially made frozen shoestrings (only because I had an Ore-Ida coupon and it was double coupon days at a local store, so they were almost free).

I got to thinking about all of the used cooking oil. Seemed like a shame to completely waste it. So, doing a little online search, I came upon a method to purify it for reuse. I had about 2 1/2 cups of used canola oil, which had gotten fairly brown by the time I was done doing several batches of deep fried foods, and especially dark after doing the calamari, as the flour comes off when it cooks and burns a bit.

1) Strain the solid residue out of the oil. IF you've cooked something with a lot of fine particles or starch, like flour-coated foods or raw, starchy potatoes, you should actually let the oil sit for a while to allow the fine particles to settle out, and then pour off the oil.

2) When you've removed the solids and particulates, pour an amount of water equal to the volume of oil into a large pot or kettle with deep sides. Pour in your oil. Add about 1/2 teaspoon of salt per quart of total liquid to to the pot.

3) Bring the oil and water mixture to the boil, and then boil it hard for about 5 to 10 minutes. The darker, more scorched, and/or more strongly flavored the oil, the longer you should boil the mixture. BE VERY CAREFUL NOT TO BOIL IT OVER OR TO ALLOW ALL OF THE WATER TO BOIL AWAY (it shouldn't boil away in just a few minutes, unless you're doing a small volume).

4) Remove from the heat, and set aside to settle out. It takes about 10 to 30 minutes for the oil to completely separate and come to the top.

5) Carefully pour the oil/water mixture into a fat separator cup. Pour off the water portion as completely as possible and discard.

6) Put the oil portion back into the deep pot or kettle. Over medium heat, bring to the boil (which for oil is hotter, obviously, than for water. Reduce heat until it is boiling and popping a bit, but slowly. The goal here is to evaporate all of the retained water. When the oil becomes very clear looking and no longer makes ANY sound (no popping or sizzling sounds), has no more bubbles rising, and no more steam comes to the top, it's done.

7) Allow to cool, then bottle in an airtight container for reuse.

OK --- the results. It was interesting. The resulting volume of oil I got was very close to the original amount of used frying oil I started with, so I didn't lose much in the process. The color lightened visibly, and quite a bit, but it's still darker than what I started with (canola oil, very light in color). The flavor is tolerable, but it still retains just a bit of fishiness. It isn't too "burnt" tasting. I think it would be fine to use for cooking another batch of seafood and maybe the fries or hushpuppies to go with it, but I wouldn't want to use it for something like fried doughnuts.

Now, as to the safety of this method. Well, some carcinogens form, apparently, whenever foods are fried or browned. Not being either a health professional or a food professional, I wouldn't want to make judgments either way -- like anything, done in limited amounts, would probably be OK.

As far as the kitchen safety of this goes, well, anytime you use hot oil, you do need to be careful of the dangers of splatters, burns, spills, and kitchen fires. So, if anyone tries this, be careful.

As far as the economics of this, it takes a bit of electricity (or gas, if that's what you use), but I can't imagine it would cost as much as the price of the oil involved, since oil and other staples are going up, up, up.

[hippywife]

1. Thanx for sharing those results.

I really never deep fry anything very often. I did beer battered shrimp a couple of weeks ago in under an inch of oil in the big cast irons skillet. They turned out really good and I didn't have enough oil used in the process to worry about it.

If I ever do, I'll know where to come look for this. I have been craving some fresh cut fries for a while and just keep putting them out of my mind. LOL

:hi:

[Warpy]

2. The original oil will partially hydrogenate

so it won't be as light as the original with subsequent uses. Also, the order in which you fry things is important: always fry potatoes last because they'll absorb any fishy taste the oil has picked up. Sometimes, though, I'll use oil I've fried shrimp in precisely for that flavor and use it the next time I do a batch of deep fried tofu.

Mostly what you need to do is let the big crud settle down into the bottom then strain the little crud out. I've used coffee filters for it and they work slowly but well.

I've never boiled it with water. I've also never used commercial oil refreshers they use in fast food restaurants. I usually use deep fry oil no more than three times, at which point the smoke point has lowered to the point it's just no good for that purpose any more.

[Denninmi]

3. Well, I don't know if I'd bother to do this again.

I just like to experiment with these things. At least I know it CAN be done if necessary.

I actually usually save most fats, greases, and oils and throw them on the kitchen scraps I give the birds. I don't know if I'm going to give them coronary artery disease, but they seem to like it, especially this time of year when it's cold out there.

Of course, being chickens and such, they eat ANYTHING that doesn't eat them first.

[Warpy]

6. Birds love SUET

and one of the things to hang outdoors in winter is a suet block with seeds in it. It's candy to wintering birdies.

[pengillian101]

4. Well, I just remember what my Grandma and Mom did in the 1950's

Grandma kept solidified bacon grease in a container next to the stove (yikes - not even in the fridge) but we never died from it. I was just little, but man, she could cook some good stuff.

My Mom was a waitress at a high-end steak house in the 1950's, who learned how to make good steaks and fries. For the fries, she would would double fry (fry, drain and fry again) for that great color and crunchiness.

Afterward, strain the oil through a cheesecloth in a wire strainer, and pour into a jar and refrigerate. That oil was used over and over like that for fries.

That's what the steakhouse did, and so did she. Delish fries.

So much for my reminiscing :-) hope it helped.

[Syrinx]

5. I fried a little bacon last night to put in a salad

Trying to stay healthy, so I'm eating salad... with bacon and cheese added in. :rofl:

And I saved the bacon fat in a coffee cup, that is sitting on my stove, as we speak, unrefrigerated. Home fries here we come! (Or maybe I'll use to season some greens, or something.)

And double-frying french fries is the only way to go. Three minutes at 325, followed by three to four minutes at 375. Perfect fries.

[pengillian101]

8. Hey Syrinx, invite me over!

Sounds good to me! Green beans in bacon fat - yummy!

:hi:

[Warpy]

7. My granny kept chicken fat and used it.

My Irish mother kept bacon fat, but I never saw her use it for much of anything, she hated cooking and it showed.

But no, it was never refrigerated. Those of us who survived the 50s and earlier times grew up on rancid fat.

[trud]

9. pengillian101

You beat me to it, I was just going to post that. Our generation survived, so I guess this is okay :-)

By the time oil gets hot enough to fry something , it's probably killed off anything growing in it. Plus not long before that the only refrigeration was blocks of ice in the icebox. I sure wish I had the icebox we used to have.

[Lucinda]

10. You can also fry potato wedges to clarify the oil.

It will pick up the fishiness and you can strain any particulates out with cheesecloth. The test way is interesting but seems way too dangerous for me. I have three cats underfoot. No water/oil boiling for me. LOL

[pengillian101]

11. Boy, I hear ya!

"I have three cats underfoot. No water/oil boiling for me. LOL"

Our two cats are always underfoot in the kitchen - drives me nuts. They get fresh canned food every morning and their crunchies cat-dish is always full. Whaddya gonna do? They ain't changing after 20 years.

:hi:

[Lucinda]

12. Not likely!

We just had a power failure...and we have black floors. I stayed up a while, but I couldn't see the cats under my feet (they are all dark) even with pretty good candlelight. One was really scared and stuck to me like glue. I finally gave up and napped for a while. :)

[pengillian101]

13. Oh, I see!

They were just wanting to be around YOU!

No food involved, lol!

How sweet. They just needed a snuggle.

[Lucinda]

14. They aren't storm fans. :)

And they ARE all snuggle addicts. LOL

[trud]

15. remember saving the wrappers from margarine and butter

to grease cookie sheets and other baking pans with.