How we tested
Mozzarella is the most popular cheese in America, even beating out cheddar for the top spot. You can find it in a variety of forms: string cheese, dense blocks of “pizza cheese” for grating, shredded cheese, tiny balls of snacking cheese, and larger balls of “fresh” high-moisture mozzarella, which we use when we want the milkiest, richest flavor and a tender, soft texture.
Mozzarella is a remarkably simple cheese; in fact, you can make it at home in less than an hour using a few specialty ingredients. According to the traditional method, milk, rennet, and an acid are heated until the curds separate from the whey. The curds are strained, salted, and then plunged into hot water to make them flexible. Once removed from the water, they are stretched until they become smooth and elastic. While this stretching was once done by hand, most manufacturers now rely on machines to do it. Finally, the cheese is shaped into either a block or a ball and cooled. Unlike aged cheeses such as cheddar and Brie, mozzarella is ready to eat right away.
What Exactly Is “Fresh” Mozzarella?
For centuries, mozzarella has been made in Italy using buffalo's milk, which contains twice as much butterfat as cow's milk, for a notably rich cheese. Authentic mozzarella di bufala campana is a Denominazione di Origine Protetta product hailing from the Campania region of Italy, which includes Naples. But since buffalo mozzarella is not aged and is usually produced with unpasteurized milk, it has an extremely short shelf life—only four to five days—and is therefore difficult to export to the United States.
While there are a few buffalo mozzarella producers in the United States, most domestic “fresh” mozzarella is instead made from less-expensive pasteurized cow's milk (this same cheese is called fior di latte in Italy). The term “fresh mozzarella” is not recognized by the U.S. Food and Drug Administration, so manufacturers can label any product that meets the guidelines for mozzarella as “fresh.” However, cheesemakers typically use the word to denote a style of mozzarella that is higher in moisture than block mozzarella and is eaten raw (“fresh”) rather than cooked (though a few recipes, such as pizza margherita, do rely on melted fresh mozzarella). Mass-market domestic mozzarellas also have a longer shelf life than Italian buffalo mozzarella.
With all this in mind, we set out to find our favorite fresh mozzarella. We focused on products labeled “fresh” and sold in shrink-wrapped balls or packed in brine. We rounded up eight nationally available products priced from $0.32 to $1.00 per ounce and tasted them plain, uncooked in our recipe for Cherry Tomato Caprese Salad, and melted onto miniature toasts.
We didn't notice much difference in the mozzarellas when melted; however, flavor and texture differences were apparent in the plain and Caprese salad tastings. Our least favorite cheeses were bland, with no hint of tang—just dull milk flavor. We also didn't love the other extreme; some products were overly salty and too tangy—not what we expect from mozzarella cheese. Tasters preferred balanced mozzarellas that were moderately salty and slightly tangy, with delicate grassy, floral notes.
A Moderate Amount of Sodium Makes the Best Mozzarella Ingredient labels showed that the sodium levels of the products in our lineup ranged from 50 to 110 milligrams per 1-ounce serving. Tasters thought cheeses at the low end of this range were bland and boring, and these cheeses fell to the bottom of our rankings. Mozzarellas at the high end of this range fared a bit better, but a few tasters found them overly salty. We preferred products with a moderate amount of sodium (85 to 95 milligrams per serving); they were savory and flavorful without being overwhelmingly salty.
The Role of Acidity in Mozzarella Flavor
Zeroing in on differences in tang took a bit more digging. During the mozzarella-making process, acid is added to help the curds stretch. This acid comes in the form of vinegar, cheese culture (which causes natural bacteria to form and convert milk sugars into lactic acid), lactic acid, and/or citric acid. We identified the type of acidification simply by looking at product labels and noticed a trend: Products acidified with lactic or citric acid were at the bottom of our rankings, while higher-ranking mozzarellas used vinegar or cheese culture.
Mark Johnson, assistant director of the Wisconsin Center for Dairy Research at the University of Wisconsin–Madison, told us that citric acid is more effective at stretching the mozzarella, so less acid needs to be used. This means that the cheese ends up with a higher pH (it is less acidic) and tastes sweeter and not at all tangy. By contrast, more vinegar or cheese culture is needed to acidify mozzarella, so cheeses produced this way have a lower pH (they're more acidic) and a characteristic tang.
Lab tests confirmed this. The cheeses in our lineup ranged in pH from 5.8 to 6.2, and experts told us that these slight variations in acidity can translate into major flavor differences. The two highest-pH cheeses were acidified with lactic or citric acid; tasters found them too bland and sweet. The two lowest-pH cheeses were acidified with vinegar or cheese culture; tasters found them a bit too tart. Our favorite mozzarellas had a moderate pH (about 6.0) and a subtle tangy flavor tasters loved; they were also acidified with vinegar or cheese culture but may have been made using slightly less vinegar or cheese culture than the lower-pH cheeses. Still, other factors can influence pH, including naturally occurring bacteria, the cows' diet, and the original fat and moisture content of the milk. While manufacturers wouldn't share details with us, it's clear that our favorite mozzarellas were made with a balanced amount of acid in the form of vinegar or cheese culture.
Acid and Moisture Affect Mozzarella Texture
Variations in pH can also affect texture. Johnson explained that cheese is a tightly bound matrix of protein (called casein) and fat, and acid helps break down this tough protein. In general, this means that mozzarellas with a higher pH (less acidic) have a firmer texture. Again, this tracked with our results; tasters found the higher-pH cheeses a bit dense and noted that one lower-pH cheese was too soft and slightly weepy. Our favorite products, which had a moderate pH of about 6.0, were soft, plush, and tender.
The two highest-rated rated cheeses also had high moisture contents, more than 60 percent, that resulted in melt-in-your-mouth creaminess when tasted uncooked. The driest product (with about 49 percent moisture) was dense and tough, similar to block cheese for grating. However, texture differences were less noticeable when we melted the cheeses; all were perfectly milky, stringy, and chewy.
A Better Mozzarella
Our favorite cheese was BelGioioso Fresh Mozzarella ($7.99 for 8 ounces). It had all the qualities we demand in a mozzarella: moderate tang, moderate sodium, and high moisture. These attributes worked together to create a cheese with a savory richness; a buttery, tender curd; and a clean, milky flavor. One note: Our winning cheese comes packaged in a vacuum-sealed ball. The company also produces a brine-packed fresh mozzarella and confirmed that this is made using a slightly different process. We sampled it before settling on our lineup, but tasters preferred the vacuum-packed version.
Twenty-one America's Test Kitchen staffers sampled eight fresh mozzarellas plain (twice, to control for variability), in our recipe for Cherry Tomato Caprese Salad, and melted onto miniature toasts. We sent samples of each to an independent lab to have pH, moisture, fat, and protein levels calculated. Sodium level and type of acid were taken from ingredient labels. Sodium levels were standardized for comparison, using a serving size of 1 ounce. Products appear in order of preference.