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Is it really necessary to refrigerate peanut butter?

I've never refrigerated it before, but I'm now noticing "refrigerate after opening" on the label of a jar of "natural" peanut butter (peanuts, salt).

sharonc asked in Other-Food & Drink 11 months ago | Report

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  • Labcoat_small
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    Danger

    Peanut butter has a very high fat percentage (primarily in the form of oil) and as such has a low water percentage. Usually less than 2%. It's this low hydration that prevents bacteria and fungi from growing and, in turn, prevents spoilage.

    However, natural oxidation can make peanut butter go rancid by breaking down the long hydrocarbon chains that make up the oils. This usually takes a long time (6-12 months) and high natural levels of the antioxidant vitamin E help slow the process. It usually takes many months. It's not really bad to eat rancid peanut butter I should add, but why would you?

    It is the same thing that happens to olive oil if you expose it to air for too long, but olive oil goes off much quicker.

    So, no. You don't generally need to refrigerate your peanut butter, but if you do, it will last a bit longer and won't separate as readily (this happens much more rapidly to the 'natural' kinds), if you care that is. Also, if you get lots of crumbs and stuff in the jar and leave it, those little pieces could become islands for mold at room temp.

    Danger answered in Other-Food & Drink 11 months ago | Report
    2 comments by HoneyBadger and Danger…
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  • Sleestak_small
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    I don't refrigerate it and I've never had it go bad.

    I don't refrigerate butter, ketchup, mustard, hot sauce, vegatable oil, and a whole bunch of other things that "require" refrigeration either.

    I think it's a joint conspiracy by the refrigerator companies and the food manufacturers to get everyone to buy a larger, more expensive refrigerator and to throw out food that's past its "expiration date," even for foods that don't have realistic expirations (like parmesan cheese).

    Urgutha Forka answered in Other-Food & Drink 11 months ago | Report
    1 comment by keshmeshi…
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  • Icon_small
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    For the good quality, natural nut butters, I say yes. Over-processed garbage like Skippy will last until the apocalypse unrefrigerated, but natural peanut butter can go rancid. I've never let nut butters go rancid since I refrigerate them, but I have let whole nuts go bad, and it's nasty.

    keshmeshi answered in Other-Food & Drink 11 months ago | Report
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  • Bierce1_small
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    The other reason for the oil-slick on top of the natural peanut butter is to shield it from oxygen, humidity, and spoilage.

    Black Beetles in Amber answered in Other-Food & Drink 11 months ago | Report
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  • Livi_small
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    Yes, for the 'natural' stuff.

    No for Jif

    Livi answered in Other-Food & Drink 11 months ago | Report
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  • Spiralavatar_small
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    Nope. I've had an opened jar of peanut butter out for more than 6 months. It's fine. Keep in mind I have no sense of smell, but to my eyes and my tongue, it seems the same as when I first opened it.

    rogitator answered in Other-Food & Drink 11 months ago | Report
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