Blue cheese is a general classification of cow's milk, sheep's milk, or goat's milk cheeses that have had cultures of the moldPenicillium added so that the final product is spotted or veined throughout with blue, blue-gray or blue-green mould, 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.
The characteristic flavor of blue cheeses tends to be sharp and salty. The smell of this food is due both to the mould 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 foot odor and other human body odors.
Blue cheese is believed to have been discovered by accident, when cheeses were stored in naturally temperature and moisture controlled caves, which happened to be favourable environments for many varieties of harmless mould. Roquefort is mentioned in texts as far back as 79 AD. Gorgonzola is one of the oldest known blue cheeses, having been created around 879 AD, though it is said that it did not actually contain blue veins until around the 11th century. Stilton is a relatively new addition becoming popular sometime in the early 18th century. Many varieties of blue cheese that originated subsequently, such as the 20th century Danablu and Cambozola, were an attempt to fill the demand for Roquefort-style cheeses that were prohibitive due to either cost or politics.
100 g of generic blue cheese contains the following nutritional values according to the USDA: