Why Is Liquid Drained from Roasted Eggplant?

Raw eggplant has a spongy interior, and most of the spaces in this structure are filled with water. During roasting, heat breaks down the cell walls; the sponge collapses and releases the water it was holding. When the eggplant is taken off the heat, this water is still distributed throughout the flesh, and it starts to run out as the eggplant is peeled and cut. The amount may surprise you: one medium eggplant can release enough water to fill a small bowl. That is why recipes for roasted eggplant give quantities by count rather than weight; its weight drops considerably as it drains. For the same reason, drain roasted eggplant before freezing it, or ice crystals will form in the bag.

If this water stays in the dish, it causes 2 problems. The first is texture: eggplant dip and roasted eggplant salad should be creamy, but excess water disrupts that texture and makes the mixture spread across the plate. The second is the sauce: yogurt, garlic, or olive oil will not cling to waterlogged eggplant and will sit on top in a separate layer. The water also dilutes the flavor. The same problem occurs in hot dishes made with roasted eggplant; excess water thins the sauce and lengthens the simmering time in the pot.

Draining is simple. Put the peeled eggplant in a fine-mesh strainer, set a bowl underneath, and leave it in the refrigerator or on the counter. Half an hour is enough for most recipes; leave it longer if you want a thicker dip. During this time, leave the eggplant in large pieces; cutting it beforehand makes the water drain faster but also damages the texture and crushes the fibers. Choose a wide strainer; in a narrow one, the eggplant piles up and the pieces underneath cannot release their liquid.

Squeezing is not the right method. Squeezing eggplant in your hands or in a cloth crushes its fibers, destroys its creamy texture, and leaves a stringy, dry mass. Squeezing also removes some of the flavor along with the water. The right approach is to wait; do not put any weight on the eggplant in the strainer. At most, press it lightly with the back of a spoon, then leave it to drain. Taste the drained liquid before discarding it; if it is not bitter, you can use it in soup or sauce.

One other thing happens while the eggplant drains: exposure to air causes it to darken. To slow this, squeeze a few drops of lemon juice over the eggplant in the strainer or cover the container with plastic wrap. Lemon also brightens the flavor. However, do not soak the eggplant in lemon water; water enters its texture and replaces the liquid you just drained away. After draining, shred the eggplant with two forks or by hand rather than chopping it with a knife to preserve its fibrous texture. Let the shredded eggplant rest for a while after combining it with the sauce so the flavors can meld.