Sure, they're largely interchangeable, but at least know what you're buying.
Despite the fact that they’re all hard, highly-gratable, Italian cheeses, Parmesan, Parmigiano-Reggiano, and Pecorino Romano are not one in the same. A stroll through the cheese section of your local grocery store can be somewhat intimidating, especially when all the blocks look eerily similar and have names suggesting that they may or may not be interchangeable. I often find myself thinking, “Is there any truth here?!” Knowing the subtle differences between all three will make your next roundabout through this somewhat confusing corner of the grocery store easy, breezy, and...CHEESY (sorry, had to).
According to the FDA, anything labeled “Parmesan,” “Parmigiano,” or “reggiano” is characterized as a cheese made from cow’s milk with a “granular texture and hard and brittle rind.” Rennet, which is an animal protein or “milk-clotting enzyme that produces curd formation,” is also present in the cheese, thus making this cheese unsuitable for vegetarians. If you’re wondering about that grated stuff in a jar with a green lid, well, it technically does fall in this category, however it’s only about 91% Parmesan cheese. The remaining percentage is made up of artificial fillers and anti-clumping agents (potentially even wood!).
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Think of this one as the Champagne of hard cheeses—it has worked hard to get that name on its label, so don’t you dare go comparing it to some grocery store brand sparkling moscato. Parmigiano-Reggiano has a Protected Designation of Origin status (Denominazione di Origine Protetta or DOP, if you speak-a the Italiano). This means that the ingredients, sourcing, and production are heavily monitored in order for the final product to the bear the name of this highly desirable cheese. It’s similar to Parmesan in that it’s also a cow’s milk cheese that contains rennet (ahem, sorry vegetarians), but the standards of its aging and origin are much more rigorous.
It’s made in only two Northern Italian regions and it must be aged for at least a year, but some are aged for up to 36 months. Because of its limited production, long aging time, and producers’ careful attention to detail during the making of the cheese, this product is the real deal. It’s likely going to cost a little more than Parmesan, but whether it’s for table use or cooking, there is no denying that it can elevate just about anything. No dig at Parmesan, but this stuff is assuredly next level.
Like Parmigiano-Reggiano, it bears that same DOP, so you can rest assured that it’s legit. Produced in Sardinia, a region in central Italy, Pecorino Romano is a cheese produced from sheep’s milk, so its differences in flavor and texture are unavoidable. Since sheep’s milk possesses a more bitter taste than cow’s milk, Pecorino Romano is much saltier and stronger tasting than your classic Parm. Also, the aging window for Pecorino Romano, 5-8 months, is slightly shorter than that of Parmigiano-Reggiano. And to the hopeful vegetarians who are on the edges of their seats, I have bad news—there’s still rennet in Pecorino Romano, so it’s best to stay away.
All of that said, when it comes down to buying some version of hard Italian cheese like you dang-well know what you’re doing, it’s probably in your best interest to stay away from any of the stuff that is pre-shredded or pre-grated, as cheese starts to lose its moisture once it’s cut. Ask the cheesemonger how recently your cheese was cut (he he he), and if it’s been a while, see if they’ll cut you a fresh block. While you’re checking out that massive cut wheel, go ahead and get a good look at the label. What does it say? Are we doing Champagne today, or are we opting for the sparkling moscato?