No, not all mozzarella is pasteurized. Most mozzarella sold in U.S. grocery stores is made from pasteurized milk, but fresh mozzarella made from raw or thermized milk does exist, particularly from artisan producers and in traditional Italian varieties. The distinction matters for food safety, especially for pregnant people and anyone with a compromised immune system.
What U.S. Grocery Store Mozzarella Is Made From
The shredded mozzarella, string cheese, and block mozzarella you find in a typical American supermarket are almost always made from pasteurized cow’s milk. Major manufacturers pasteurize their milk before cheesemaking as standard practice, and this type of mozzarella is considered safe for all populations, including pregnant women. The CDC lists mozzarella made with pasteurized milk as a safer food choice during pregnancy.
Fresh mozzarella sold in water or brine at grocery chains is also typically pasteurized, but this is where you need to start reading labels. Smaller producers and imported varieties may use raw or thermized milk. U.S. labeling regulations require cheeses made from unpasteurized milk to state “unpasteurized,” “raw milk,” or “heat treated” on the package. If the label says “pasteurized milk” in the ingredient list, you’re good. If it doesn’t mention pasteurization at all, check more carefully or contact the manufacturer.
How Traditional Italian Mozzarella Differs
Mozzarella di Bufala Campana, the famous PDO-protected buffalo mozzarella from Italy, can legally be made from either raw or pasteurized water buffalo milk. Some Italian dairies fully pasteurize their milk before production, while others use a process called thermization, which heats milk to around 62°C (144°F) for 15 seconds. That’s slightly below the temperature and time required for full pasteurization, so thermized milk retains more of its natural bacterial diversity but doesn’t eliminate pathogens as reliably.
If you’re buying imported Italian mozzarella at a specialty shop or cheese counter, ask whether it was made from pasteurized or raw milk. Imported cheeses sold in the U.S. must either be made from pasteurized milk or aged for at least 60 days. Since fresh mozzarella is not aged, any legally imported fresh mozzarella should be made from pasteurized milk. That said, artisan and farmstead producers at local markets may operate differently, so it’s worth confirming.
Why Stretching Doesn’t Replace Pasteurization
Mozzarella is a stretched-curd cheese, meaning the curds are pulled and kneaded in hot water during production. The stretching water reaches 60 to 85°C (140 to 185°F), and the cheese itself hits 50 to 65°C (122 to 149°F) as it leaves the stretching process. Some people assume this step is hot enough to kill harmful bacteria the way pasteurization does.
It isn’t reliable enough. Research on mozzarella production has found that common starter bacteria survive stretching at lower water temperatures (around 55°C in the center of the curd), and the same applies to potential pathogens. Higher stretching temperatures do kill more microorganisms and extend shelf life, but the process doesn’t consistently destroy dangerous bacteria like Listeria throughout the entire mass of cheese. For fresh mozzarella meant to be eaten without further cooking, pasteurization of the milk beforehand is specifically recommended because stretching alone can’t guarantee safety.
The Listeria Risk With Raw Milk Soft Cheeses
Fresh mozzarella is a soft, high-moisture cheese, and that matters for food safety. Soft cheeses with high moisture content are more hospitable to Listeria than hard, aged cheeses like Parmesan or aged cheddar. The aging process in hard cheeses lowers moisture and increases acidity over weeks or months, creating conditions that suppress bacterial growth. Fresh mozzarella skips that step entirely.
Cheese made from unpasteurized milk is more likely to contain Listeria and other foodborne pathogens. The CDC has tracked multiple multistate Listeria outbreaks linked to soft cheeses and raw milk products in recent years, including incidents in 2014, 2017, 2021, and 2024. While those outbreaks primarily involved queso fresco-style cheeses rather than mozzarella specifically, the underlying risk factors are the same: soft texture, high moisture, low acidity, and no significant aging.
How to Tell if Your Mozzarella Is Pasteurized
Check the ingredient list on the package. Pasteurized mozzarella will list “pasteurized milk” or “pasteurized part-skim milk” as the first ingredient. If you see “raw milk,” “unpasteurized,” or “heat treated,” the milk was not fully pasteurized before cheesemaking.
For mozzarella bought at a deli counter, cheese shop, or farmers market where there’s no ingredient label in front of you, ask the seller directly. Vendors should know whether their product uses pasteurized or raw milk. If they can’t tell you, treat it as unpasteurized to be safe.
If you’re pregnant, immunocompromised, over 65, or feeding young children, the simplest approach is to stick with clearly labeled pasteurized mozzarella from a major brand. Alternatively, heating any mozzarella to 165°F (as on a pizza or in a baked dish) will kill Listeria and other pathogens regardless of whether the original milk was pasteurized.