Depending on the size of the egg, albumen accounts for most of an egg’s liquid weight, about 66%. The white contains more than half the egg’s total protein, a majority of the egg’s niacin, riboflavin, magnesium, potassium and sodium, and none of the fat. The white of a large egg contains about 17 calories. Albumen color is opalescent and doesn’t appear white until an egg is beaten or cooked.