Egg White

Egg White: Nutrition, Properties and Complete Guide

The egg white — known in scientific and culinary contexts as the albumen — is the clear, viscous fluid that surrounds and protects the egg yolk, enclosed within the shell. It accounts for approximately 60% of the total weight of a large egg and serves as both a nutritional reserve of protein for a developing embryo and a mechanical and antimicrobial protective layer. The egg white consists of approximately 90% water and 10% proteins — primarily ovalbumin (54% of egg white protein), conalbumin (13%), ovomucoid (11%), lysozyme (3.5%), and several other minor proteins. These proteins have a wide range of biological functions: conalbumin binds iron and has antimicrobial properties; lysozyme is an enzyme that attacks bacterial cell walls; ovomucin contributes to the viscosity that gives fresh egg whites their thick consistency. The protein quality of egg white albumin is exceptional — it has historically been used as the reference standard for biological protein value and has a perfect score on the protein digestibility-corrected amino acid score (PDCAAS). In cooking, the structural and aerating properties of egg white proteins are as important as their nutritional value — they are capable of extraordinary functional transformations.

Nutritional Value of Egg White

Egg white provides 52 kcal and 10.9 g of protein per 100 g, with just 0.17 g of fat — an extraordinary protein-to-calorie ratio. A single large egg white weighs approximately 30–35 g and provides around 15–18 kcal and 3.5–4 g of protein. Egg white contains no fat and no cholesterol. It provides riboflavin (B2), selenium, magnesium, and potassium in meaningful amounts, along with smaller quantities of folate, B6, and zinc. The sodium content (approximately 166 mg per 100 g) is the highest component of whole egg sodium. Note: raw egg white contains avidin — a glycoprotein that binds biotin (vitamin B7) and prevents its absorption. Regular consumption of large quantities of raw egg white over a prolonged period can cause biotin deficiency. Cooking destroys avidin and eliminates this concern — cooked egg white is fully nutritious.

Health Benefits of Egg White

Egg white is one of the most efficient sources of high-quality complete protein available at minimal caloric cost. The protein provides all nine essential amino acids in proportions that support muscle protein synthesis — making it a historically important protein in sports nutrition and bodybuilding, where the egg-white omelette became a dietary staple before powdered protein supplements became widely available. The absence of fat and cholesterol makes egg white suitable for those managing cholesterol, those on low-fat diets, and those seeking maximum protein at minimum calories. For those eating the whole egg and concerned about cholesterol, using a combination of whole eggs with additional whites — for example, one whole egg mixed with two additional whites — provides more protein with proportionally less fat and cholesterol than using whole eggs alone. Selenium from egg whites supports thyroid function and antioxidant defence.

How to Use Egg White

Egg whites are extraordinarily versatile in cooking and baking. Whipped: when beaten vigorously, the protein network unfolds and surrounds air bubbles in a stable foam — used in meringue, soufflé, mousse, angel food cake, macarons, and pavlova. The key to stable egg white foam: use a spotlessly clean bowl and beater (any fat prevents proper aeration), add cream of tartar (1/8 tsp per white) for stability, and avoid overbeating past stiff peaks. Cooked: egg whites set cleanly and firmly at temperatures lower than whole eggs, making them ideal for protein-rich omelettes, scrambled egg dishes, and egg white frittatas. As a glaze: egg white brushed onto pastry before baking produces a glossy, pale gold finish. As a clarifier: simmered in stock, egg white proteins coagulate and draw out impurities, then are strained out — the technique that produces consommé. Surplus egg whites freeze very well (three to four months) and can be thawed and used without loss of functional properties.