It is, of course, entirely unnecessary to point out that salt is inherently nondenominational.
While kosher salt comes from the sea and is certified at the factory as meeting the strict criteria of Jewish dietary laws, the rabbi’s blessing has no more effect on flavor than does the priest’s consecration of a communion wafer.
Kosher salt is exactly the same, chemically, as any other salt. It is pure sodium chloride, and like all salt intended for human consumption, must be greater than 97.5 percent pure, according to U.S. law. The only pragmatic difference between it and secular salt is in the size and shape of the grains, the kosher variety being coarser and usually flakier. Its main use is in the koshering process, which involves covering meat or poultry with a blanket of salt to purify it.
It’s also useful for certain nonritualistic purposes, however, because of its coarser grains, and that’s the only reason it is sometimes specified over regular table salt. Food “experts” who claim that kosher salt has a different flavor from regular salt should be politely asked to go pound it.
Take a look at some ordinary granulated table salt under a magnifying lens. Unless you’ve had a good course in chemistry, you’ll be astonished at how regularly shaped the grains are. They’re actually tiny cubes! You’ll notice that most of them are somewhat the worse for wear because their sharp edges have been worn off in jostling against their neighbors, and some have been chipped so badly that they’re practically spheres. But you can tell that originally, they all tried very hard to be perfect cubes.
The cubic shape arises from the geometric arrangement of the sodium and chlorine atoms that make up the salt particles. For reasons that chemistry teachers can take half a semester to explain (if they explain it at all), and that I won’t burden you with here, it happens that when sodium and chlorine atoms combine to form sodium chloride, they arrange themselves into a perfectly square pattern. (It has to do with their electric charges and their relative sizes.)
When zillions of sodium and chlorine atoms come together to make a three-dimensional salt crystal that’s big enough to see, the shape of that entire crystal is going to reflect the square geometric arrangement of its individual atoms. A cube is simply a square in three dimensions, no?
While the compact cubic grains of ordinary table salt are just right for shooting smoothly through the holes in a salt shaker, kosher salt must have more “cling” to it for coating meat in the koshering process.
Even though the individual atoms inside are still arranged in a cubic pattern, the grains have a more irregular outer shape. They come out that way in the form of a crust on the surface of sea water when it is evaporated slowly. In kosher law, that’s considered to be a more natural process than taking salt from a mine, dissolving it in water, and then evaporating the brine with coal or gas heat, which is how most other table salt is prepared.
If you look at kosher salt under a magnifying glass, you won’t see cubes. The crystals will be irregular and flaky.
Chefs often prefer to cook with kosher salt because it is easier to pinch with the fingers and throw into a pot, and they can feel exactly how much they’re using. As soon as it dissolves in the food, however, the former size and shape of its grains become totally immaterial.