If you want to know why salting eggplants is a thing, you have to care about history. Welllllll, that’s not totally true. You just have to care about the history of the eggplant—the Treaty of Ghent and the Jurassic Period and the Industrial Revolution are kind of irrelevant in this situation. The thing is, we salt sliced eggplant before cooking because of what the vegetable used to be like. Confused? Allow us to explain.
The first time someone ever cooked an eggplant, it was a much different vegetable than the one we're familiar with. Sure, the shape and color and size were probably different than the eggplants we eat now, but the most noticeable difference was the flavor. Once upon a time, eggplants tasted incredibly bitter, and salting them before cooking helped to draw out and eliminate some of that astringency. But things have changed.
These days, that overwhelming bitterness has been bred out of eggplants. You might still catch a hint of it every once in a while, but for the most part, the eggplants we know today don’t need the same kind of help mellowing out. Which, as you have probably gathered, means we don’t have to salt eggplants in order to get rid of bitterness because, well, there isn't that much to get rid of. Fun!
So, are there any other reasons to salt eggplants? Well, besides the fact that someone’s great grandparent told us to do it, we sometimes salt eggplants to help remove some of the excess moisture that's trapped in the vegetable. Generally speaking, when we apply heat to raw ingredients—be it a vegetable, piece of bread, or slab of meat—we're hoping to get water out of something, thus concentrating its flavor. Salting the cut side of an eggplant before you cook it helps draw out water—we won’t go into the specific science, but it involves words like “osmosis” and “ions”—and jump starts that process. Not only that, it helps to season the eggplant from the inside out, which means the creamy interior will taste every bit as delicious as the browned, caramelized exterior that you sprinkled with salt right before cooking.
