Great question. And one that kind of stirs up some controversy. I'll get to the controversy in just a sec.
But first, let's just go over the basics on choosing an eggplant. Now, we're talking about the large globe or Mediterranean eggplants. When you're in the produce section, look for an eggplant with a nice shiny skin, and dark purple. If the skin is dull that means that the eggplant has been hanging around a little too long and you want to avoid that.
The key to bitterness in an eggplant is the seeds. The fewer seeds, the less bitter the eggplant will be. Ah, but how do you tell how many seeds? Here's the controversy. Some say that there are male and female eggplants and the males have fewer seeds, and thus are less bitter. How to determine an eggplant's sex? Well, look at the round end, opposite the stem. If there is an indentation -- kind of like a belly button, an "inny" specifically -- then this is a female eggplant. The male eggplant will have an almost smooth feel on the round end, perhaps just a small nick or scar.
The controversy lies in the fact that some plant experts say there is no such thing as a male and female eggplant. I have to admit that I've seen the difference in the supposed male and female eggplants myself.
But if you want to be a purist, here's another way to tell eggplants apart. Start by choosing eggplants that are similar in size and shape. Then weigh each; the one weighing less will -- generally -- have fewer seeds and be less bitter.
