Just about all it really takes to make peanut butter are peanuts, salt and a grinder. I myself remember when instant peanut butter-making machines were all the rage, back in the 70’s. Just an electric grinder with a hopper full of roasted peanuts on top was all they were. A gift shop in the suburb I grew up in had one. Feed in a dollar or so in quarters and after much whining and crunching, a half pint of fresh butter would slurp into a cup. Neat. Though I remember that the thrill of watching it done was a lot more fun than eating the end product, which, wholesome though it might have been, was clumpy, gritty and oily. My mother always demanded that my twin sister and I use up what we had before we could go make more (frustrating my plan to turn my room into America’s first National Strategic Peanut Butter Reserve) so we didn’t get back to the shop much.
These very same problems, the tendency for peanut butter to separate into peanut oil and peanut meal, are what drove Joseph Rosefield to improve the product a hundred years ago. He discovered that adding a small amount of hydrogenated shortening (about 3%) to the fresh-ground butter was all it took to firm up the oil (if you followed the earlier discussion on chocolate tempering, the principle is the same: fat crystals from the solid shortening grow in the oil, creating a semi-solid mass). Of course a little sugar in the mix didn’t hurt, and the end result was what we in America still know as Peter Pan. You can buy peanut butter on Amazon now?