The other week, a friend brought over some pre-grated Parmigiano-Reggiano to cook with. It was from a nice cheese shop, and you could tell that the cheese had been grated very recently. It tasted good and wasn't dry or dusty. I was impressed with the quality, and the convenience factor was pretty high.
But we didn't use all of it. And now I have one more reason why I will never buy cheese pre-grated.
It molded. And quickly, too.
Only a week later, blue spots of mold appeared throughout the entire package. Had the cheese been left in wedge form, it never would have molded in that amount of time. After maybe a few weeks the surface would get a bit spotty, but even then, you can face the cheese by slicing off the offending edge, thereby preserving the interior.
Cheese is perishable, so obviously it'll eventually go bad, but why hasten the process, especially for a cheese like parmesan, with a shelf life that's almost eternal?
The more exposure that cheese has to air, the more it loses flavor and aroma. Oxygen is also what brings on spoilage. Cheese that's prepped for you may be more convenient, but it's more expensive, too! A cheese's freshness and flavor quotient goes way down when it's pre-grated, -shredded, or -sliced. As far as I'm concerned, a bit of elbow grease to grate is totally worth the payoff in quality. And shelf life.