Blue cheeses are produced with cow's milk, sheep's milk, or goat's milk and ripened with cultures of the mold Penicillium. The final product is characterized by green, grey, blue or black veins or spots of mold throughout the body. This process also softens the texture and develops the distinctive blue flavour.
The origin of Blue cheese has an interesting story. It is thought to have been invented by accident when a drunken cheese maker left behind a half-eaten loaf of bread in moist cheese caves. When he returned back, he discovered that the mold covering the bread had transformed it into a blue cheese.
Blue cheese is also identified by a peculiar smell that comes from the cultivated bacteria. The flavour of the cheese depends on the type of blue cheese, shape, size, climate of the curing and the length of ageing. But it generally tends to be sharp and salty.