Blue cheese (or bleu 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 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.

The characteristic flavor of blue cheeses tends to be sharp and a bit salty. The smell of this food is both due to the mold and to types of bacteria encouraged to grow on the cheese: for example, the bacterium Brevibacterium linens is responsible for the smell of many blue cheeses, as well as the smells of "stinky" feet and other human body odor.

Alternative forms

• bleu cheese

blue cheese (plural blue cheeses)

1. A kind of cheese with bluish mold in it.