What makes the best block? It all comes down to fat, moisture, and acid.
How We Tested
Mozzarella conjures up images of Italian food, but most of what’s sold as mozzarella in this country isn’t actually Italian at all—it’s an American invention.
Traditional Italian mozzarella is made by acidifying whole buffalo milk and heating the mixture in hot water until the solid curds separate from the liquid whey. The curds are then stretched and pulled, by hand or machine, until they form elastic balls of cheese. This type of mozzarella is packed in brine and labeled “fresh” mozzarella; we like it in uncooked applications, where its milky flavor and soft texture shine through.
The rest of the mozzarella you find in supermarkets—blocks, shredded, string cheese, and slices—is American mozzarella, invented in the early 1900s by Italian immigrants who wanted to make a cheese with a longer shelf life. It’s made much like traditional mozzarella, but the curds are cooked and stirred longer before stretching, resulting in a cheese with a lower moisture content, higher acidity, and more longevity. This Americanized mozzarella is easy to grate and melts beautifully.
To find the best block mozzarella, we picked six nationally available products, three whole-milk varieties and three part-skim. We also included our winning preshredded whole-milk mozzarella. We tasted the cheeses plain and melted on our Sheet Pan Pizza.
While all of the cheeses shredded easily and melted well, our tasters preferred the fuller, more dairy-rich flavor of whole-milk cheeses to part-skim in both tastings. To get a better read on fat levels, we sent all of the cheeses to an independent lab for analysis. Our favorites, which were made from whole milk, had up to 48 percent fat in their dry solids (a measurement of how much of the cheese is fat once the water is removed), while lower-ranking part-skim cheeses were as little as 42 percent fat. According to the U.S. Food and Drug Administration (FDA), products must be labeled “part-skim” if they contain less than 45 percent fat in their dry solids. Tasters thought these cheeses had a mild flavor and a rubbery texture. We preferred products with 47 percent or 48 percent fat, which tasted milky and rich.
The one exception was the preshredded cheese, which tasters singled out for its drier, slightly powdery texture (likely from cellulose added to prevent clumping) when tasted plain. While the added starch made for drier cheese that was a tad chewier (although still pretty good) when melted on pizza, most tasters agreed that its moderate 45 percent fat content lent a creamy, rich flavor. It landed in the middle of our rankings, drawing the dividing line between the whole-milk and part-skim blocks.
But fat tells only one part of the story. According to the FDA, mozzarella can contain anywhere from 45 percent to 60 percent moisture. Wet, milky fresh mozzarella has 60 percent moisture; on the low end are the dense, firm blocks labeled “low-moisture mozzarella.” We’ve always considered all block mozzarella to be low-moisture. But the FDA requires “low-moisture” on the labels of only mozzarellas with 45 percent to 52 percent moisture. Those with 52 percent moisture or higher can be called simply “mozzarella,” regardless of whether it’s a fresh ball of cheese or a denser, shreddable block.
It was telling, then, that our top two products had no mention of “low-moisture” on their labels; they were called only “mozzarella.” Our lab results showed that these two samples had 53 percent and 52 percent moisture—they were dry enough to shred and melt well but had enough moisture to have a soft, smooth texture (even when melted) that approached that of fresh mozzarella.
Top-ranked mozzarellas had another thing in common: They’re acidulated with vinegar—in the traditional manner of American mozzarella—rather than with cheese culture. Our tasters found these vinegar-acidulated cheeses richer and more pleasantly tangy than cheeses produced using cheese cultures.
For the best all-around texture—and especially flavor—avoid block mozzarellas labeled “part-skim” and “low-moisture” and look for those labeled simply “mozzarella,” with whole milk and vinegar on the ingredient label. Our favorite of these was Polly-O Whole Milk Mozzarella Cheese. With the highest milk fat and moisture percentages of all the cheeses we tried, this whole-milk mozzarella approximated the rich, milky flavor we love in fresh mozzarella while still maintaining a springy, shreddable texture that melted effortlessly on pizza.
Twenty-one America’s Test Kitchen staffers sampled six block-style mozzarellas alongside our winning preshredded mozzarella in two blind tastings—plain and on our Sheet Pan Pizza. In both tests, block cheeses were shredded to mask visual differences. Milk fat and moisture percentages were measured and reported by an independent lab. Results from the tastings were averaged, and products appear in order of preference.