The Scientific Name: Albumen
The most precise and scientific name for the egg white is albumen. This term is used across various fields, from food science and biology to nutrition. The word itself comes from the Latin album, meaning "white". This clear, protective fluid is a reservoir of water, minerals, and proteins, designed to support and protect a developing embryo. It is a highly complex substance, made up of multiple protein layers that contribute to the egg white's overall structure and function.
The Layers of Albumen
Within the egg, the albumen is not a uniform substance but is divided into four distinct layers. These layers vary in viscosity and composition and work together to protect the yolk and nourish a potential embryo.
- Outer Thin Albumen: This watery layer is the outermost part of the egg white, lying just inside the shell membrane. It makes up the largest proportion of the liquid egg white.
- Thick Albumen: A more viscous and gel-like layer surrounds the yolk. This layer's structure is maintained by a complex of proteins, including ovomucin.
- Inner Thin Albumen: A small, watery layer that lies directly next to the yolk.
- Chalaziferous Layer and Chalazae: This dense, rope-like layer holds the yolk in the center of the egg. The twisted, cord-like structures are the chalazae, which act as anchors.
Historical and Culinary Names
Throughout history and in different culinary contexts, egg whites have been known by other names. The use of beaten egg whites as a baking agent dates back to the Renaissance, and its uses have evolved over time.
- Glair or Glaire: This term is historical and still used in specific crafts like bookbinding, where egg white was used as a gilding adhesive to give covers a shiny finish.
- Egg White Albumen: This phrase refers more specifically to the concentrated protein extract from egg whites used in supplements, rather than the whole liquid component. The most abundant protein in egg white is ovalbumin, which is what most people mean when they refer to the protein benefits.
Chemical Composition and Functional Properties
Egg white is approximately 90% water and 10% protein. This simple composition belies a powerful set of functional properties that make it a versatile ingredient in the kitchen. The proteins, including ovalbumin, ovotransferrin, and ovomucoid, are responsible for these key functions.
- Foaming: When whisked, the proteins in egg white denature and create a network that traps air bubbles. This property is essential for making meringues, soufflés, and angel food cake.
- Binding: The protein's ability to coagulate when heated allows it to bind other ingredients together, as seen in meatballs, fritters, and bread coatings.
- Clarifying: In cooking, egg whites can be used to clarify cloudy broths and consommé. The proteins attract and bind to small, suspended particles, which then rise to the surface and can be easily skimmed off.
- Emulsifying: Although the yolk is a more powerful emulsifier, egg whites can also help to bring together liquids that normally don't mix, like oil and water.
Comparison Table: Egg White vs. Egg Yolk
| Feature | Egg White (Albumen) | Egg Yolk |
|---|---|---|
| Appearance | Clear and viscous liquid | Yellow, dense, and opaque |
| Composition | Primarily water (90%) and protein (10%) | Water (50%), protein (16%), lipids/fat (32%) |
| Fat Content | Almost no fat | Contains all the fat in the egg |
| Cholesterol | Contains no cholesterol | Contains all the cholesterol in the egg |
| Primary Function | Protects the yolk, provides protein, creates foam | Provides vitamins, minerals, and fat |
| Culinary Use | Foaming agent, binder, clarifier | Emulsifier, thickener, enricher |
Understanding the Proteins in Egg White
The proteins within egg white are not a single substance but a mixture of different types, each with its own unique function.
- Ovalbumin: The most abundant protein, making up over half of the egg white protein. It is a phosphoglycoprotein that is key to the egg white's foaming and gelling properties.
- Ovotransferrin (Conalbumin): Makes up about 12% of egg white protein. It can bind metal ions like iron, giving it antibacterial properties.
- Ovomucoid: This protein is known for its heat resistance and for being the major allergen in egg whites.
- Lysozyme: An enzyme with potent antibacterial activity, it is a key part of the egg's defense system against microorganisms.
- Ovomucin: The protein responsible for the gelatinous, thick texture of the egg white.
Conclusion
While most people casually refer to it as the 'egg white,' its formal name is albumen. This term accurately describes the clear liquid that surrounds the yolk, packed with water and high-quality protein. From the science behind its multilayered structure to its specific functions in culinary arts, understanding what do you call egg whites reveals the rich complexity and versatility of this common household food item. Whether you're whipping it into a meringue or using it to clarify a stock, the albumen is a powerhouse ingredient with a fascinating history and composition. For more detailed information on egg chemistry, you can consult academic resources like those on ScienceDirect.
