Penicillium roqueforti
The blue-green mould that forms the veins of Roquefort, Stilton, Gorgonzola and most blue cheeses.
Also: P. roqueforti, blue mould
Penicillium roqueforti is the mould behind almost every blue cheese. It is named after Roquefort, where it was once grown on loaves of rye bread left to go mouldy in the caves, then dried and ground into a powder added to the curd. Today cultured spores are added to the milk or curd. Blue cheeses are made with loose, open curd and then pierced with needles so air reaches inside, where the mould grows along the cracks and holes into blue-green veins. It breaks down fat as well as protein, which creates the peppery, spicy notes of Roquefort, Stilton, Gorgonzola, Cabrales and Danish blue. Despite the name, it is not the mould used to make penicillin.