Eggplants are among the fussiest of foods when it comes to harvesting, handling and storage. The vegetables are easily damaged, with small bruises on their skins quickly turning into brown spots that can penetrate the flesh. The good news is that these imperfections don't make the entire eggplant inedible or unsafe. Unless your recipe calls for a whole, unpeeled eggplant, you can avoid nasty surprises by getting rid of the bitter-tasting, rotted skin and flesh while preparing your eggplant dish.
When you have your choice of eggplants, look for ones that are shiny and smooth, with no pitting or discoloration, as well as a green stem. These are the most likely to currently have tender, non-bitter flesh, and to be moist enough to avoid future bruising. If you are using your own imperfect garden eggplants, or if previously bought eggplants look questionable when you pull them from the refrigerator, peeling and cutting the vegetables is the only way to evaluate quality. Slightly imperfect eggplants will have smallish brown spots that don't extend far from the outer skin into the flesh. More widespread rotting will find larger brown spots that penetrate more deeply into the white parts of the eggplant.
If you need to work with the eggplants you have on hand, sort them into the good, the iffy and the ugly. Choose only unblemished eggplants when you're cooking dishes requiring cooking them whole and unpeeled, or in perfect round slices. Select soft-spotted eggplant for dishes that demand more careful processing. Finally, throw away eggplants that seem to have mold on the skin or flesh, emit a foul smell and are heavily spotted and tough on the inside.
With eggplants that are only slightly blemished internally, the best option is to peel them, then dig or cut away the brown and tough sections. Next, chop the eggplant into chunks and brush them with lemon to prevent more discoloration prior to cooking. With a heavily spotted eggplant, the initial treatment is the same, but you will probably be removing more exterior flesh before cutting the eggplant into chunks, as well as discarding surrounding areas that are tough. Because these are the iffiest kind of acceptable eggplants, it's best to soak them in salted water, which will extract any bitter taste from the usable flesh, before cooking.
If you can feel soft spots on the eggplant's skin, it's best to choose a recipe that calls for chopping or slicing the vegetable rather than cooking it whole. In this way, you'll be able to chop off brown spots rather than inadvertently add bitterness to the dish. Save the spread known as baba ghanoush for your best eggplants, because the recipe calls for oven-roasting a whole, unpeeled eggplant. Eggplants with only a few brown spots can still be used, sliced, as with eggplant parmigiana -- just set aside any slices that have rotten spots on them. Use the salvageable parts of the most imperfect eggplants in dishes involving peeled, cubed eggplant, such as ratatouille.