Composition

A whole egg consists primarily of a yolk, a white, and a shell. In addition, it contains a membrane that lines the shell and forms an air cell at the large end, and two white strands called chalazae that hold the yolk centered. Figure 24.1 is a cross-sectional diagram that shows the location of these features.

1. The yolk is high in both fat and protein, and it contains iron and several vitamins. Its color ranges from light to dark yellow, depending on the diet of the chicken.

2. The white is primarily albumin protein, which is clear and soluble when raw but white and firm when coagulated. The white also contains sulfur.

   The white has two parts: a thick portion that surrounds the yolk and a thinner, more liquid portion outside of this.

3. The shell is not the perfect package, in spite of what you may have heard. Not only is it fragile but it is also porous, allowing odors and flavors to be absorbed by the egg and allowing the egg to lose moisture even if unbroken.