Blue cheese is a general classification of cow's

milk, sheep's milk, or goat's milk cheeses that

have had cultures of the mold Penicillium added

so that the final product is spotted or veined

throughout with blue, blue-gray or blue-green

mold, and carries a distinct smell, either from

that or various specially cultivated bacteria.

Some blue cheeses are injected with spores

before the curds form and others have spores

mixed in with the curds after they form. Blue

cheeses are typically aged in a temperature

controlled environment such as a cave. Blue

cheese can be eaten by itself or can be crumbled

or melted into or over foods.

In the European Union, many blue cheeses such

as Roquefort, Gorgonzola and Blue Stilton carry a

protected designation of origin, meaning they

can bear the name only if they have been made in

a particular region in a certain country. Similarly,

individual countries have protections of their own

such as France's Appellation d'Origine Contrôlée

and Italy's Denominazione di Origine Protetta.

Blue cheeses with no protected origin name are

designated simply "blue cheese".

The characteristic flavor of blue cheeses tends to

be sharp and salty. The smell of this food is due

both to the mold and to types of bacteria

encouraged to grow on the cheese: for example,

the bacterium Brevibacterium linens

responsible for the smell of many blue cheeses,

as well as foot odor and other human body

odors.