I have a jar of peanut butter ground from peanuts by me at the store (meaning no preservatives). It’s been sitting around for a month or so and still looks, smells, and tastes the same. It’s sitting unrefrigerated in a twisting ziplock jar… does this stuff last forever?
In the same amount of time, most other nonpackaged foods in our house has grown moldy many times over. The fruits have rotted, the left-over pasta in the fridge has turned blue-green, my bagels have literally started to crawl with a surface of what looks like a horde of teeny maggots… but the peanut butter just sits there looking perfectly placid and healthy.
I really don’t know why- I’m sure someone else will pop in with that answer, but my dad stores his opened peanutbutter in the cabinet, not the fridge (like I do). Maybe he’s cruisin’ for a botulism poisonin’, who knows. He hasn’t died yet and either did I my entire childhood.
It makes sense for natural peanut butter, which is made only from ground peanuts and salt (optionally). The oil in natural peanut butter will separate and float to the top since it is liquid at room temperature. If you stir the peanut butter to mix in the oil and then refrigerate it, the oil will solidify enough to prevent separation. This type of peanut butter is pretty easy to spread even when it’s cold.
Interestingly, I’ve noticed little to no separation with the fresh-ground stuff. Refrigeration does make it harder to spread and it loses some of its crunchy, delicious texture and becomes more like the generic slimy glop that store-bought PB resembles.
So how would you detect the presence (or lack thereof) of something like this?
I take it “oil becoming rancid” isn’t necessarily an indication of this… would it be obviously different in terms of taste or anything else, or will I only know when I’m 50 and dying of cancer?
Damn you, delicious peanut butter of my youth, damn you!
But…true fresh-ground peanut butter is too good to give up!
(I bet those peanuts in the grinder have been inspected)
My store also has grinders with almonds, honey-roasted peanuts, and organic peanuts. I find that the peanut butter made from the organic peanuts is dryer and saltier than the PB made from plain ole peanuts. I don’t like it so I’m glad they’ve kept the option of the evil non-organic peanuts, unlike the local health food place.
I too have noticed that the fresh-ground doesn’t have the separating problem most other PBs have, even the natural made.
Actually, what’s the difference between fresh-ground and natural? I love the texture that fresh-ground has, but even natural comes in smooth and chunky just like Jif. I’ve never found a natural PB that’s like fresh-ground. I’m not sure how to describe the texture - it’s between crunchy and smooth; there aren’t any large bits to ‘crunch’, but it’s rough enough that it isn’t as sticky as smooth can be.
Ah, we haven’t had this question for a while. The answer is that the water activity of peanut butter is so low that almost no microbes can grow in it - same reason honey doesn’t go bad either. There’s water in peanut butter, but it’s so bound up with sugars and fats that it’s not available to help nasty bacteria grow. That said, there are a few rare species of yeasts and molds that can slowly grow in it, so it’s not impossible, just very unusual.
Of course, microbial spoilage is only one part of “going bad”. The other thing that can happen is the oxidation of some of the fats, causing them to go rancid. So if your PB smells funny, it’ll probably taste bad, but it won’t hurt you.
Nut oils oxidize quickly with exposure to heat, light, and air, and become not-very-healthy for human intake (free radicals and all that). Many nuts on store shelves are old enough that the oils have oxidized. They will go completely rancid eventually, which you’ll be able to taste.
Peanuts often carry a mold that produces a toxic substance called aflatoxin, a carcinogenic substance. It has many health effects, most of them long-term rather than immediate. Commercial peanut butters (and many other foods) are carefully monitored to ensure it does not carry a heavy does, as aflatoxin is most dangerous to children. In the case of homemade stuff all bets are off. The longer you let it sit in a warm place the worse off you are. Just refrigerate the damn stuff.
It’s a very very different smell to regular oil. There’s no real vocabulary to describe it, but it’s got an unpleasant “top note” to it. I’ve eaten rancidising peanut butter and other oils before (and sometimes noticed this in catering scenarios - cafés and so on) and suffered no contemporaneous ill effects.
While it’s true that aflatoxin-producing molds are often found on peanuts, the peanuts are indeed carefully screened to prevent them getting into peanut butter. And, for the reasons stated above, even if some of the mold gets in there, it’s unlikely to grow enough to produce significant amounts of toxin.
Wait wait wait: so I can store my peanut butter in the cabinet? I honestly thought my dad was trying to kill himself via peanut bacteria all these years. Well, shit. That stuff’s going in the cabinet then.
The only good reason I’ve heard to store commercial peanut butter in the fridge is if you live in a super-hot area and are worried about it becoming rancid (or melting to runny peanut soupy-butter). I grew up in the Midwest, and the first person I’d ever seen who put it in the fridge was my aunt and uncle, who lived in Texas.
