# Possible to freshen rancid oils?



## KE6WNH (Feb 20, 2009)

When I deodorize and decolorize my grease, I just put about 3 inches of water beneath it in a big stock pot and let the steam bubble up through the fat for a couple of hours... but can this also work for driving the rancidity out of oils and fats which have not gone off too badly? I'm only asking because I have a jar of coconut oil which smells slightly painty.


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## Lindy (Feb 20, 2009)

From what I understand you need to actually render your used fats.  Now please keep in mind I haven't done this myself so what I am sharing is just what I have been told.

To render your fats you need to place them in a large pot with enough water to float the fats.  Bring it to a boil and boil for about 30 minutes (please double check this time) or until everything is liquid.  Take off the heat and let cool.  The fat will have solidified and be floating - lift the fat off the water which you will dispose of - scrape ickies (that is a technical term just so you know) and then you should repeat this process at least three times to make sure you have all impurities out of the fat.  Once rendered you can keep it in a cool area in your home, but it won't need to be refrigerated.

I hope others will come by who have actually rendered fat to give us their expertise......

Cheers
Lindy


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## MikeInPdx (Feb 20, 2009)

Don't know if it's expertise, but if you put a couple of cups of vinegar in your first boiling, it helps take a lot of the stinkies out of rancid fat.

Otherwise, Lindy pretty much nailed how you process it.....the only difference in terminology is I use is I call it cleaning the fat. I render raw fats out of chunks of meat and cracklings.


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## KE6WNH (Feb 20, 2009)

To Lindy... rendering is exactly what I've been doing to my grease. I was confused at first, because in chemistry, "rendering" means adding a strong acid (e.g., muriatic acid) to the soap solution in order to extract the waxy fatty acids. As for things like ham rind, beef trimmings, etc etc... I typically fry them down, pour and screen out as much grease as I can, then feed the fried pieces of meat to my dog. The ickies are then pretty much absent, but OTOH the grease will be yellow and have a meaty smell until it's steamed.

To Mike... thanks for the tip! Friends from the South who eat a lot of chitterlings have told me vinegar in the pot will make the cooking less stinky, so I'll definitely try it once I save more raw grease. The chemicals in grease after meat has been cooked in it, are mostly nitrogen-based alkalies (one, liquid quinoline, smells like burnt steak)... so an acid like vinegar ought to neutralize them pretty well.

Still dunno how well it would work against rancidity, though I could always try it and post the results...


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## kaseencook (Feb 21, 2009)

When you mean rancid do you mean oxidized? I would think that if the oils have been oxidized (like in a DOS situation) the oil has reacted with the oxygen in the air which breaks weak double bonds in some oils and the oil is no longer the same substance..... perhaps it may not be possible to recover oil that has gone "rancid" because of oxidation, because you would have to reverse the chemical reaction somehow. . I tried to find if anyone has written about reversing oxidation on the web, but didn't find much, prob because it's not done. I'm not that up on the chemistry of oxidation or rendering, but I just had that idea. Good Luck!


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## TheStone86 (Nov 16, 2020)

I'm new to soapmaking, but have some huge containers of oils, some a bit smelly from poor storage with poor coverings in a hot room for years.  I just came across this patent:





						US20080102181A1 - Rejuvenation of used cooking oil          - Google Patents
					

Implements for decolorization, deodorization and deoxidization of used or filtered spent cooking oil are disclosed to improve on the service life of cooking oil and the health aspects of fried foods. This can be achieved on a small to large scale by simple implements filled with a mixture of...



					patents.google.com
				




Perhaps activated charcoal can getter up all the stinky compounds that have formed.  Looks like an aquarium filter element (an activated charcoal 'teabag') could be the ticket to rancid oil rejuvenation.  I'll be trying it with some shea butter to see if that makes the butter better.  Better bet I'll get back to you if it works.  I anticipate the shea will have to be liquid for this to work, and since diffusion will be the driving force, it may take a long time; like days, I'm guessing.


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