reserved egg white

Reserved egg white refers to egg white (albumen) that has been separated and set aside—typically from recipes that use only the yolk—for use in subsequent preparations. Egg white is the translucent, viscous protein-rich liquid surrounding the yolk, composed primarily of water (approximately 90%) and proteins including ovalbumin, ovotransferrin, ovomucoid, and lysozyme. The term "reserved" indicates intentional preservation for culinary application, whether immediate or after refrigeration or freezing. Quality reserved egg whites maintain their protein structure and foaming capacity, essential for meringues, mousses, and binding applications.

When properly stored in clean, grease-free containers, reserved egg whites remain functionally stable for several days refrigerated or several months frozen, provided they are protected from contamination and oxidation. The proteins denature minimally under proper storage conditions, retaining their ability to incorporate air and stabilize emulsions or foams.

Reserved egg whites serve multiple essential functions across classical and contemporary cuisine. They are fundamental to meringue preparations (Swiss, French, and Italian), mousse desserts, angel food cakes, and soufflés, where their ability to incorporate and stabilize air creates structure and volume. In savory applications, egg whites clarify stocks and consommés through the raft method, binding together impurities for crystal-clear broths. They also function as a binder in forcemeats and terrines, and as a coating agent in traditional recipes like egg white-washed pastry glazes. The proteins denature when heated, coagulating to set foams and stabilize emulsions, making reserved egg whites invaluable for both hot and cold preparations.