Egg Yolk is the nutrient‑dense yellow part of an egg used worldwide in cooking for sauces, custards, emulsions and as a rich garnish. It provides about 16.2g of protein per 100g while contributing most of an egg's fat and flavor. Nutritionally, egg yolks are notable for concentrated micronutrients — especially choline, vitamin B12 and selenium — and deliver a complete amino acid profile, though they are also a source of saturated fat so are best used in balance within the diet.