The veining doesn’t look the same in all blue cheeses—why?
It’s no secret that what creates a cheese’s blue veining is the presence of a penicillium mold, typically Penicillium roqueforti. But there’s another, perhaps lesser-known key factor in mold growth: oxygen, without which these molds wouldn’t exist. As a result, blue veins will grow where air pockets are, their shapes and patterns reflecting the pockets in the curd. The size and dimension of these pockets are influenced by the curd’s firmness. Pastes that become softer and creamier may display more wispy veins (as in Gorgonzola Dolce), while pastes that retain a firmer texture aren’t as likely to collapse, thus maintaining the air pockets (as in Roquefort).
According to Carr Valley cheesemaker Sid Cook, veining is also shaped by how mold spores are incorporated during the make process. In Carr Valley’s case, “blue spores are purposely added to the milk, instead of to the curd,” he says, so that the “bloom is consistent and even throughout the cheese.” And of course, those deep, straight veins we often see in blue cheeses are created when fresh wheels are purposely punctured to create airflow inside the cheese.