Mold in Blue Cheese
Most cheeses have a small amount of controlled internal and surface mold that we don't see. Blue cheese is made much like any other hard cheese, but mold spores are intentionally introduced to the production. Not all mold is edible, however, and the surface mold that forms after distribution should not be consumed. Cutting the mold off the cheese is acceptable--about an inch from the growth--but don't place the knife in the mold or you could cross-contaminate the remainder of the cheese. Liquid-based cheeses or dairy products, such as cottage cheese, ricotta cheese, sour cream and yogurt, should not be eaten at all if mold forms on them, because the mold can contaminate the liquid base throughout the product. Other popular variations of blue cheeses are Roquefort, Gorgonzola, Stilton, Maytag and Danablu.
The History of Blue Cheese
The mold that is used for blue cheese is called Penicillium roqueforti, named after the region in France where the cheese was supposedly discovered. The legend goes that a shepherdess left her lunch of cheese and bread in the Roquefort caves, and after a couple weeks, she discovered the molded lunch and decided to try it. This story cannot be confirmed, but it is true that the caves of Roquefort were used to age and cure cheeses because of the penicillium roqueforti mold spores present in them that enhanced the ripening of cheeses. Eventually, controlled mold spores were intentionally injected or mixed into the cheese to distribute it more evenly.
How It's Made
Blue cheese starts out like any other cheese: Cow's, goat's or sheep's milk is curdled. Then moldy bread is ground into fine dust and mixed into the curds as a starter for the mold. Whey is removed from the curds, and the product is pressed and drained. Some recipes induce the mold after formation by making holes in the cheese and injecting the penicillium roqueforti bacteria. Then the cheese is aged; many are still aged in caves enriched with the moldy bacteria. The ripening of the cheese allows the bacteria and microbes to act on the curds of the cheese changing its structure. Mold forms and breaks complex molecules into simple ones, which smooths out the fibrous structure of the cheese and provides its pungent odor and sharp, salty flavor.