Since some rich, yeast-based doughs require the use of eggs, the following will provide the information a baker needs to ensure that egg safety is always observed. An egg is composed of an outer shell made of a calcium compound, such as calcium carbonate. The shell color does not affect the thickness of the shell or the quality, flavor, nutritive value, or cooking characteristics of the egg, but is determined by the breed of chicken or other bird that produced it. Brown eggs come from reddish brown hens such as Rhode Island Reds, Plymouth Rocks, and New Hampshires (obviously all New England favorites). White eggs are produced by Leghorns, America’s most common breed of chicken. Rare breeds such as Araucanas lay eggs in an array of pastel blue and green shades. No matter the color, if the eggs are handled in the same manner, the taste and nutrition will be equal.