Weeping

Weeping, also called syneresis, is what happens when a gel lets go of some of the liquid it holds. It leaves a watery layer, as seen in yogurt or sour cream.

Over time the structure tends to contract, so it can no longer hold the water well. Temperature plays a part too, because some gels are looser when hot and tighten up when cooled, squeezing liquid out. In frozen desserts, water loss can show up as ice crystals.

In the bakeshop the same effect shows up when overheated egg custards curdle and release liquid, or when starch and fruit gels are stored too long. Careful cooking, correct amounts of gelling agent and cool, steady storage reduce it.