An egg is made up of three main components: shell, egg white and egg yolk. The shell, together with the inner membranes and the cuticle, constitutes a barrier that opposes the entry of microorganisms from the outer surface towards the inside of the egg. If you are among those who consider eggs with a dark shell more genuine and nutritious than those with a white shell, be aware that it is only a false belief: the colour of the shell depends exclusively on the breed of hens! The albumen, also known as egg white, occupies 60% of the egg’s volume and consists of about 88% water, 10% protein and small amounts of sugars and minerals. The egg yolk, on the other hand, is the constituent of the egg that is richest in nutrients. It is made up of approximately 50% water and 30% lipids, while the rest is made up essentially of proteins. Approximately 58% of a whole egg is made from egg white, 33% from yolk and 9% from shell. This subdivision indicates that, on average, by breaking down a large egg of about 70 g (class L) into its 3 components, the egg white will weigh 41 g, the yolk 23 g and the shell 6 g. At first glance, the eggs may all look the same to each other but, in reality, they have some characteristics that clearly distinguish them from one another. In fact, it is possible to subdivide them by size (S, M, L, XL), freshness (fresh or extra-fresh) and type of breeding (organic, free-range, cage-free, standard). Source: www.alimentinutrizione.it