The birth month of a Parma cheese also makes a difference, not only the aging time, like most people believe. When in May the cows get the fresh grass, the milk taste changes.
This change can be tasted later in the cheese, so a Parmigiano, produced in May/June, will always taste different from the one produced in late summer or winter, even if it has the same age.
Parma cheese has to be at least 12 month old and to pass the exam of the Consortium (an inspector tags the wheel with a small hammer) to be called officially “Parmigiano Reggiano”, but for eating it pure, it should be 18 or 24 month old. From 30 month on, you eat it only with Balsamic vinegar or dried fruits and dedicate a whole course to it. Occasional I´ve tried the 40 month old, it always comes with the name and location of the cheese factory and real experts can tell the difference from one factory to the other. I´m working on that…..