Peanut butter is very high in oil and low in moisture so it takes a long time to go bad (usually good sealed on the shelf for a year)--when it does go bad, it goes rancid and you can tell right away
If you buy nuts and make your own, or buy peanut butter made fresh in a natural foods store, you need to refrigerate it right away to be sure that any aflatoxin mold spores don't take hold--this mold is very dangerous to ingest because it is carcinogenic.
If you buy nuts and make your own, or buy peanut butter made fresh in a natural foods store, you need to refrigerate it right away to be sure that any aflatoxin mold spores don't take hold--this mold is very dangerous to ingest because it is carcinogenic.