Blue cheese is any of a wide range of cheeses made with the addition of cultures of edible molds, which create blue-green spots or veins through the cheese. Blue cheeses vary in taste from very mild to strong, and from slightly sweet to salty or sharp; in colour from pale to dark; and in consistency from liquid to hard. They may have a distinctive smell, either from the mold or from various specially cultivated bacteria such as Brevibacterium linens.
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 temperature-controlled environments.