Did you know that mildew helps in the maturation process of Manchego cheese? That's why sometimes, inside a Manchego cheese D.O.P. matured naturally you can find small veins close to the rind. These veins occur occasionally with the cheese maturation process, when the mildew penetrates through small holes in its interior. In fact, it is a similar process that happens in types of cheeses such as Roquefort, Gorgonzola or Blue cheese.
These little black veins prove that the cheese has had a long maturation process and the rind is completely natural, so that, what a priori may seem a defect is simply one of the inherent qualities to its condition of handmade manchego cheese.