How are nuts and seeds cracked/shelled in large quantities?
As I was sitting in my garden last night, shelling a pumpkin seed, I was once again inspired to think about the difficulty of getting nuts and seeds out of their shells. I mean really, nature pretty much designed them to be hard for animals like us to get at, so that they could survive for long enough to germinate.
And yet, you go into the store to buy shelled nuts, and you can get perfect specimins of half-walnuts (which I have never, ever been able to do by hand) and cashews (have you ever tried shelling one of those? thought not - you would need a fire, a hammer and an anvil, and it doesn’t come out pretty) and pumpkin seeds (which I can do with my fingernails, but can’t concieve of a better way) and all manner of other nuts and seeds.
I can’t imagine a machine that could do any of these things. Nuts are irregularly sized and shaped, and very fragile, and usually encased in something that requires a lot of force to break open. I envision something that can apply pressure from many sides at once, causing the shell to shatter. This would also allow for irregularly sized/shaped nuts. But that’s just a product of my mad, late-night, pumpkin-seed-fuelled imagination.
I’ve seen a pecan cracking machine at work, but only once and I couldn’t describe it. It wasn’t very fast, but a hell of a lot faster than doing it by hand, and the nuts came out mostly whole.
I’ve seen nut-cracking machines consisting of a pair of rollers spaced *just far enough apart that they crack the shell, but not so far that they crush the kernel. 100% success rate is not required, because the results can be graded after shelling; whole kernels can be sold as such, smaller pieces can be chopped and sold as chopped nuts, or used in confectionery.
The secret of getting kernels out of nuts as whole as possible is to apply the cracking force along the long axis of the nut. Difficult to do with a hand-held nutcracker but simple for machines. Here’s a link to a small one suitable for home kitchens:
For cracking nuts the best possible hand machine is a pair of small vise-grip pliers. Once you get the hang of it you can quickly adust them to just crack the shell and leave the meat whole. I bought one that I keep in the kitchen for just that purpose. My wife hates it but then she has the manual dexterity of a bear cub whose elevator goes to the 11th story of a 12 story building.
Cashews are never sold to consumers in the shell. Cashews actually have a double shell with a caustic substance between the two shells. This presents problems other than breaking the shells and extracting the meats intact.
Black walnuts are much harder to crack than pecans. The shells are both harder and tougher, and the meats are more convoluted, making it just about impossible to extract black walnut meats intact. Even commercially cracked black walnuts are usually sold in small pieces.
Macadamias have very thick, hard shells, so it takes a lot of force to crack them. However, the shells are just about spherical, as are the nutmeats, so there’s not much risk of breaking the meats when cracking the shells. I took a tour of a macadamia nut factory once, and they explained that they grade the nuts by size and then run them between rollers that are a little closer together than the diameter of the nuts.
