egg yolk

The egg yolk is the nutrient-rich, lipid-laden central portion of a bird egg, most commonly derived from domestic chicken (Gallus gallus domesticus). Encased within the vitelline membrane and suspended in the albumen, the yolk comprises approximately 30% of the egg's total weight and is characterized by its spherical form, golden to deep yellow-orange coloration (depending on the hen's diet), and rich, creamy texture. The yolk contains approximately 50% water, 32% lipids (including cholesterol and phospholipids), and 17% proteins, along with numerous micronutrients. Yolks from different poultry species—including duck, goose, and quail—exhibit variations in size, pigmentation, and flavor intensity, with duck yolks being notably larger and more intensely colored.

The flavor profile ranges from mildly sweet and buttery in fresh yolks to more pronounced and savory in aged or pastured eggs. Fresh yolks from pasture-raised hens typically display more saturated orange coloration and a richer taste due to the birds' diverse diet of grasses and insects.

Egg yolks are fundamental to classical and modern cuisine, serving as emulsifiers, binders, and enrichment agents in both sweet and savory preparations. In sauces, yolks stabilize emulsions in hollandaise, béarnaise, and mayonnaise; in baking, they contribute moisture, richness, and golden color to cakes, custards, pastry creams, and ice creams. Yolks are essential to pasta dough and fresh pasta production, particularly in Italian traditions (e.g., tagliatelle, pappardelle). They are also key in French preparations such as crème brûlée, sabayon, and pâtisserie applications. In Asian cuisines, preserved salted yolks feature in Chinese dim sum and pastries, while yolks are cured in various traditions to create concentrated umami-rich condiments. Tempering yolks with warm liquid prevents coagulation and enables their use in custard-based preparations.