Which cooking oil(s) will be least likely to turn rancid?

July 30, 2013 12:07 PM

I cook with Dutch Oven sometimes. After you cook, you clean and very lightly oil the oven. Problem is, I don't use the dutch oven often so the next time I cook, the oil is rancid. I've read that Coconut oil never goes rancid and is the best to use. I've read that Crisco never goes rancid and is the best to use. I've read the oil with the highest smokepoint (avocado oil) is the best to use. I've read that the oil with the lowest oxidation index is the best to use (I have no idea which oil that is). No one seems to know. If any one of you have advice or knowlege, I would like to hear it!
posted by luvmywife to Food & Drink (15 answers total)

How long are you going between uses of your dutch oven? This is how I care for my cast iron pans, and I've never had the oil go rancid. What is leading you to believe that the oil is rancid? Could it be off flavors from the last time you cooked, perhaps? How are you cleaning the ovens - using salt or using soap?

I use salt to scrub out my pans, then dry over heat, and finally regular old vegetable oil - half a teaspoon in my ten inch pan, wipe it all around with a paper towel. It's really not very much oil, just enough to make the surface shiny, but not enough to puddle.
posted by hungrybruno at 12:21 PM on July 30, 2013

I use olive oil on my cast iron, and after rubbing it in, wipe away the excess. I have never had it go rancid. I've sometimes gone months between uses of the pans.
posted by jennaratrix at 12:21 PM on July 30, 2013

My personal, unsubstantiated experience, picked up from a similar question, is that safflower oil is the best thing in the world so far to season any kind of cast iron. I won't use anything else now. The difference between what safflower oil will do to for your Dutch Oven and what other oils will do is remarkable. You can get in in most large grocery stores, all health food stores, or on the internet. A little bit will last a long time. It is also a pretty great neutral oil with a very high smoke point to cook with.

Also, if you are having problems with rancidity, two other pieces of advice: You are probably using too much oil. It should be a light coat, and after it has bonded with the hot metal for several minutes, you should wipe off any shiny excess. And finally, store your dutch oven with the lid off so that air can get in.

One last freebie-- Renegade Java coder and Permaculture gadfly Paul Wheaton is really annoying, but he has some excellent advice on how to care for cast iron. He is best experienced in small doses.
posted by seasparrow at 12:22 PM on July 30, 2013

I use the same method as hungrybruno, except I use coconut oil. I've never had the oil go rancid.

I would guess you might be using far too much oil or you are not cleaning your dutch oven well.
posted by inertia at 12:27 PM on July 30, 2013 [1 favorite]

We use pork lard at our house; it's easy to make, cheaper than most oils, and doesn't noticeably go rancid.

For vegetarian oils, flax, safflower and sunflower seemed to have worked well for us in the past.
posted by furnace.heart at 12:39 PM on July 30, 2013

food grade mineral oil. Also used to keep wood cutting boards nicely oiled.
posted by Gungho at 1:20 PM on July 30, 2013

http://sherylcanter.com/wordpress/2010/01/a-science-based-technique-for-seasoning-cast-iron/

Sheryl Canter's fantastic explanation of the chemistry/physics of pan seasoning. She recommends flaxseed oil.
posted by overeducated_alligator at 2:04 PM on July 30, 2013 [3 favorites]

I wouldn't use anything that you wouldn't be okay eating, say, a teaspoon of. (It can come off, especially if you leave a bit too thick of a layer.) I would NOT want to eat a teaspoon of mineral oil.

I like the technique of letting it "dry" in a hot oven (not too long) upside-down (over a baking sheet) so that any excess drips right out.

I use bacon fat and canola oil without any problem. I would also use coconut or safflower. I stay away from any oil with a distinct flavor/aroma.
posted by supercres at 2:04 PM on July 30, 2013

Don't know if this would work, but since oxidation is what makes oil go rancid, maybe you could seal up the oven in a big plastic bag between uses. Even if it's not totally airtight it would reduce the oxygen exposure. Store it somewhere dark, too.
posted by echo target at 2:29 PM on July 30, 2013

I would also recommend fully rendered lard, or any other fully hydrogenated natural oil. Crisco/shortening would also be great, if you don't care about trans-fats.
posted by gjc at 2:45 PM on July 30, 2013

I like grape seed oil and have found that it takes a long, long time to get rancid. I have terrible luck with safflower/canola oil going rancid, so I'd personally avoid that. I've also never had coconut oil go rancid on me, but it does impart a flavor that I don't necessarily want in my pots and pans, so I don't use that either, although I'm sure it would perform splendidly.
posted by quince at 3:11 PM on July 30, 2013

Seconding grapeseed oil. I'm really sensitive to rancidity and other "off" oil tastes, and after much experimentation, have found it the longest-lasting and most neutral oil around. It's what I use to season my cast iron. (I've read all the stuff about flaxseed oil, but couldn't get around the smell.)
posted by neroli at 3:35 PM on July 30, 2013

I used mineral oil to protect my cast iron skillets between days while I was sanding and completely reseasoning them. It stays liquid, won't turn rancid or degrade, and if you're wiping with a thin coat, won't put anywhere near a teaspoon in your food (1.5 - 4.5 teaspoons is the recommended dose for using mineral oil as a laxative), especially if you wipe it out again with a paper towel before cooking.

What you should really do is use the same oil you use to season the pot - and that should be an oil that does oxidize and go rancid quickly. Unrefined flaxseed oil is the only food-grade drying oil commonly available in the US. Other unrefined seed oils like sunflower and grapeseed oil are semi-drying and can also work. The logic is that the seasoning on the pot is nothing but fully oxidized/polymerized oil, bonded to the bare metal or the previous layer of seasoning.

If you heat the pot up until it smokes after rubbing with a thin (again, very thin) layer of oil, it will give a head start to the drying process, and by the next time you use the Dutch oven, you should have a non-sticky, non-greasy, seasoned surface to cook with. If it is slightly sticky or greasy, you can rub it well with a towel and touch of fresh oil.
posted by WasabiFlux at 3:55 PM on July 30, 2013 [1 favorite]

Keep it away from warm areas like near pilot lights, the top part of a double oven, or in the broiler. Being heated repeatedly, or for a long time, will make oil go rancid much more quickly.

Make sure the oil you are using is fresh -- if you get a special oil just for this pan that never gets used for anything else, that isn't going to help.
posted by yohko at 12:09 AM on July 31, 2013

I don't know about dutch ovens, but with my cast iron pans I only do the lightly oil after cleaning thing for the first few weeks of using it. After that period I find that it's pretty well seasoned and it keeps its slight flavor and non-stick properties very well when cleaning afterwards using just water and a firm brush. As far as what oil to use, I use whatever is in arm's reach when I'm oiling it, usually canola, olive, safflower or vegetable.
posted by ltisz at 2:20 AM on July 31, 2013