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In the test kitchen we go through a LOT of Parmesan cheese. And our taste tests show us time and again that real Parmigiano-Reggiano, while more expensive than imitations, is worth every penny. Because we go through so much, we often buy huge quarter wheels of Parmigiano-Reggiano and break them down ourselves into smaller wedges. While doing so we’ve often noticed that the cheese towards the rind is crumblier than that in the center. And some of our test cooks swear that the exterior cheese has better flavor and boasts more of those pleasant crunchy crystals. But is that possible? Is there really a big difference between the exterior and interior? And should that inform which part you buy? We set up an experiment to answer all of these questions.

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We first set up a blind tasting of samples of cheese taken from 3 locations on one wheel of 18-month-old Parmigiano-Reggiano. We took the samples from the very center of the wheel, from a location 1 inch in from the side and bottom rind, and a third location right between these two points. In a blind tasting, we asked tasters to describe the texture and flavor of each sample and rank them based on overall preference. Next, we took additional samples from the center and edge locations, shaved them into thin strips, and manually counted the number of crystals in each.

The result? Tasters were clear about their preferences. The sample taken closest to the rind ranked first. It was “nutty”, “complex”, and “pleasantly crumbly”. The sample taken from the very center of the wheel ranked at the bottom. Tasters found it “mild”, with a “smoother”, “plasticky” texture. The sample taken in between these 2 points scored 2nd place and was described as “middle-of-the-road” in terms of both flavor and texture. What about those crystals? Well they form as the cheese ages and dries out and the insoluble amino acid tyrosine aggregates into clumps. The cheese right next to the rind averaged 20 crystals per 10 grams of cheese while the center cheese averaged less than 9 crystals per 10 grams.

What accounts for this? When cheese ages it undergoes a complex process called proteolysis which changes its texture, melting qualities, and flavor. Our tests suggest that cheese changes over time in the same way that a roast heats up in the oven—from the outside in. Dean Sommers, cheese technologist at the University of Wisconsin-Madison agrees. According to Sommers, the outer portions of wheel of real Parmesan cheese will show the telltale signs of advanced aging—a dry, crumbly texture, a high proportion of tyrosine crystals, and a deep, complex flavor.

Moving forward we’ll definitely be seeking out corner pieces of Parmigiano-Reggiano at the supermarket. Not only will we get the authenticity guarantee of the stamp on the rind, we’ll also be buying the best part of the wheel.

ABOUT US: Located in Boston’s Seaport District in the historic Innovation and Design Building, America’s Test Kitchen features 15,000 square feet of kitchen space including multiple photography and video studios. It is the home of Cook’s Illustrated magazine and Cook’s Country magazine and is the workday destination for more than 60 test cooks, editors, and cookware specialists. Our mission is to test recipes over and over again until we understand how and why they work and until we arrive at the best version.

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