It was previously necessary to salt eggplant slices to remove bitter juices. That tendency to bitterness has mostly been bred out of the eggplant so in general I no longer follow this practice. However, that procedure did help prevent the eggplant from soaking up a bucket load of oil. So, whilst it’s not essential to salt the eggplant, I soak the slices in a bowl of water with a couple of tablespoons of salt for about 30 minutes. I find that after bathing in brine, the fried eggplant absorbs less oil.