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Jan 14, 2009 10:00 AM

Does Fat Go Bad?

What's the story here? Paula Wolfert is telling me that duck or goose fat will keep "up to four months in the refrigerator". I have a 1-liter container of mixed duck fat and lard that's been in there for about two years total, during which time I've melted it, used it, re-rendered it (carefully!) and strained it back in there, each time making up any loss with lard, I think about three times. The last time was not quite a year ago. It smells just like it always did - like fat, ya know? - and except for a skim of yellowing over the top it's showing no apparent signs of age. I'm getting ready to confit two turkey thighs, and intend to use this, plus some goose fat left over from the Christmas bird and probably a little extra lard, unless I'm told that I'm courting some dreadful disease by doing so. With documented proof, of course. Having grown up with a never-cleaned-out can of bacon grease older than I was forever in the fridge, I'm frankly skeptical...

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  1. The problem is that fats do get rancid and ingesting them is dangerous. Here's a link to an explanation.... the last sentence says it all:
    "Just a little bit rancid is just a little bit poisonous. `Nuff said."

    I must say though, I too have had rendered duck and goose fat for months in the fridge using some of each every now and then till all was gone with no ill effects.

    3 Replies
    1. re: Gio

      Rancid is not a discreet phenomena,it stinks.If you have olafactory issues preventing a clear ID is one thing,however most of the population can sniff out rancid easily.

      1. re: Gio

        The cited quote was referring to oils, not solid fat. As for rancidity, that's pretty easily detectable - the odor of oxidized oil or grease is very strong and unmistakable, and none of my fats (and I just discovered yet another container of duck fat! No, I don't clean my fridge out very often...) are giving off any rancid whiffs at all.

        Okay, I'm making my confit. I'll heat each batch of fat separately, so that if one does betray some oxidation it won't contaminate the others, and I do have a 2-lb. block of FRESH butcher's lard as backup just in case.

      2. Skeptical here also.A shelf life of 4 months seems preposterous regarding modern rendering and refrigeration.I have no intention of discarding ANY that is in my frig or freezer.All of it is clean,strained,snow white and so on.Anyone that has goose or duck fat that is clean,yet still worrysom can send it along to me.4 months???

        1. Yes, all fats will spoil, Will, but not all fats spoil at the same rate. As a matter of fact, not even different containers of the same fat will spoil at the same rate. Time, conditions, contaminants, airborne germs, all that jazz... What I do is when I get some really exceptional fat that I know I want to use every cherished drop of, I put it in tablespoon or two tablespoon portions in a small zip lock plastic bag, get the air out and freeze it. Sometimes I even freeze it in a tray, then cut it into squares and pack those in a zip lock bag and toss it in the freezer and then use it as needed. I especially love the fat from a standing rib roast for making gravies and it makes a fantastic orzo risotto. Goose and duck fat for all of the obvious reasons. I've never had any go bad in the freezer, it is not subject to freezer burn, there is no condensation in it as long as it's air tight. What could be better than that?

          1. I've never had a problem with my solid fats (bird, pig) going bad, but have discovered opened bottles of oil (or bottles which had had oil but not properly cleaned) left unchilled to smell horrible.

            In the freezer, less likely. Refrigerator--far longer before turning. On the counter, use your nose, as it might go bad really quickly, particularly in the summer.

            We also keep butter in a butter bell on the counter, and as long as the water is changed every 2-3 days, it's good for 30 days. When the water hasn't been changed, it's quite obvious.

            1. Quick update: the large container of mixed fats from multiple uses, when melted, had a darker color and a stronger smell, not bad but getting there, so I poured it back and will pitch it. The goose fat and the straight duck fat were clear and smelled nice, so that plus about a cup of lard are what the turkey's cooking in right now. But I'm sure glad we had this discussion; my thanks to everyone who chimed in.