Mozzarella is a soft, white cheese that originated in Italy. It’s made from cow’s or buffalo’s milk and has a mild flavor and distinctive stretchy, stringy texture. Fresh mozzarella, or mozzarella fresca, differs from aged mozzarella and is meant to be consumed shortly after being made. There’s an ongoing debate about whether fresh mozzarella sold in stores is pasteurized or not. Here’s an in-depth look at what pasteurization is, the pasteurization requirements for cheeses in the U.S., and whether fresh mozzarella is pasteurized.
What is pasteurization?
Pasteurization is a process of heating foods, especially dairy products, to a specific temperature for a period of time to kill harmful bacteria that can cause foodborne illness. The process was named after French scientist Louis Pasteur, who discovered that heating beer and wine was an effective way to kill bacteria and prevent spoilage.
There are several methods of pasteurization:
High Temperature Short Time (HTST)
This method heats milk to at least 161°F (72°C) for 15 seconds. It’s the minimum pasteurization temperature approved for milk and other dairy products in the U.S. HTST pasteurization kills pathogens including E. coli, Listeria, Salmonella, and Campylobacter.
Ultra Pasteurization (UP)
Also called ultra-high temperature (UHT) pasteurization, this heats milk to 280°F (138°C) for 2 seconds. The high heat makes the milk shelf-stable so it can be stored unrefrigerated until opened.
Low Temperature Long Time (LTLT)
This method heats milk to 145°F (63°C) and holds it for 30 minutes. It’s a gentler pasteurization method that results in less change to the milk’s flavor.
This batch method heats milk to 145°F (63°C) for 30 minutes in large vats. It’s commonly used for artisanal cheesemaking.
Why is pasteurization used?
The main reason pasteurization is used for dairy products like milk, cheese, yogurt and butter is to destroy any potential pathogenic bacteria that could make people sick. Raw, unpasteurized milk may contain bacteria including:
- E. coli
- Staphylococcus aureus
These types of bacteria can cause foodborne illnesses with symptoms like vomiting, diarrhea, fever and cramps. Some people are more vulnerable to complications including pregnant women, young children, older adults and those with weakened immune systems.
While pasteurization eliminates the risk of pathogens, it does slightly change the flavor of dairy products. Some cheese connoisseurs prefer the richer, more complex taste of raw milk cheeses over pasteurized versions. However, raw milk cheeses age for at least 60 days which allows time for pathogens to die off.
Pasteurization became standard practice for milk sold in the U.S. in the 1920s and 1930s when outbreaks of tuberculosis, diphtheria, scarlet fever and other milk-borne diseases were common. Mandatory pasteurization significantly improved public health and safety. Today, only a handful of U.S. states permit the sale of raw milk in retail stores.
Pasteurization requirements for cheese in the U.S.
The U.S. Food and Drug Administration (FDA) has established pasteurization guidelines for all milk and cheese products sold in interstate commerce. Here are the key requirements:
- All soft, semi-soft and hard cheeses made from raw or pasteurized milk must be aged for at least 60 days at temperatures no less than 35°F (1.7°C). Examples include cheddar, colby, Monterey jack, brick and muenster.
- The 60-day aging requirement does not apply to cheeses made from pasteurized milk if they contain certain moisture and pH values. Examples are cream cheese, queso fresco, queso blanco and Panela cheese.
- All milk used to make pasteurized blended cheeses, processed cheeses, cheese foods, cheese spreads, and related foods must be pasteurized. This includes products like American cheese, Velveeta, cheese sauces and dips.
- Soft ripened or semi-soft cheeses made from unpasteurized milk must contain a disclaimer on the label that they’re made from raw milk.
These FDA requirements are in place to protect public health and reduce cases of food poisoning. The mandatory pasteurization and aging standards eliminate pathogens that may be present in fresh cheeses.
Is fresh mozzarella pasteurized?
Fresh mozzarella, or mozzarella fresca, is a soft Italian cheese made from cow or buffalo milk. There are a few factors that determine if fresh mozzarella is pasteurized or not.
Place of origin
In Italy, mozzarella di bufala Campana – made from the milk of Mediterranean Italian water buffalo – is protected by European law. To receive Protected Designation of Origin (PDO) status, this fresh mozzarella must be made according to traditional methods. One requirement is that the milk is not pasteurized. So authentic, imported Italian buffalo mozzarella is made from raw milk.
However, most of the cow’s milk mozzarella made in Italy today does go through pasteurization. And in the U.S., all fresh mozzarella sold commercially – whether made from cow’s milk or buffalo milk – is required to be pasteurized according to FDA regulations.
Packaged vs. deli-fresh
Fresh mozzarella comes in two basic forms: packaged mozzarella sold in grocery stores, and deli-fresh mozzarella prepared on-site in Italian markets or cheese shops.
Packaged mozzarella has been pasteurized to meet FDA food safety standards. This includes domestic brands like Organic Valley, Galbani and Great Value. Perishable refrigerated mozzarella is typically pasteurized using the gentle LTLT method to preserve flavor.
The mozzarella hand-pulled into balls and sold at cheese shop deli counters may be pasteurized or unpasteurized. Small local dairies are permitted to sell raw milk cheeses that they’ve aged for over 60 days, allowing time for pathogens to die off. But these products require a raw milk disclaimer on the label per FDA rules.
There are a few clues that can help determine if fresh mozzarella has been pasteurized:
- A Pasteurized statement on the packaging indicates it’s been heat treated.
- Brands labeled mozzarella fresca or fresh mozzarella are pasteurized unless marked as raw milk.
- Tightly packaged mozzarella with longer sell by dates has been pasteurized for food safety.
- High moisture, milky mozzarella stores have heat treated their cheese.
- Deli-fresh mozzarella is raw if it contains a raw milk disclaimer.
Here is a table summarizing the pasteurization status of different types of fresh mozzarella:
|Type of Fresh Mozzarella
|Packaged mozzarella sold in grocery stores
|Mozzarella hand-pulled into balls at cheese shops
|Sometimes (if raw milk, will be labeled)
|Authentic Italian buffalo mozzarella
|No, by Italian law
|Domestic U.S. water buffalo mozzarella
|Yes, required by FDA
Does pasteurization affect mozzarella flavor?
Most cheese enthusiasts agree that pasteurization does subtly change the flavor of mozzarella. However, there is disagreement over whether the flavor improvement in raw milk cheese is significant enough to warrant any increased food safety risk.
Here’s an overview of how pasteurization impacts mozzarella:
- Fewer enzymes: The high heat of pasteurization destroys some of the natural enzymes and good bacteria that contribute to flavor.
- Less complexity: The bacteria killed during pasteurization produce many subtle flavor compounds. Raw milk mozzarella has more complex taste.
- Changed proteins: Heat alters milk proteins which can slightly change texture and water binding properties.
- Loss of freshness: Heat accelerates the breakdown of proteins and fats in cheese over time.
However, the flavor differences between raw and pasteurized mozzarella are fairly nuanced. And good dairy practices can help mitigate flavor loss in pasteurized cheeses:
- Using low-temperature vat or LTLT pasteurization methods.
- Adding additional bacterial cultures after pasteurization.
- Aging cheeses for short periods to allow flavor to develop.
- Using high-quality, fresh milk from healthy livestock.
So in summary, pasteurization does subtly change the flavor of mozzarella but likely not enough for most consumers to notice – especially when high-quality milk is used. The food safety benefits of pasteurization outweigh small potential flavor losses.
Is pasteurized mozzarella safe to eat during pregnancy?
It’s generally considered safe for pregnant women to eat pasteurized dairy products like mozzarella cheese. The pasteurization process eliminates any dangerous bacteria that could cause food poisoning and risks to the developing fetus.
Here are some tips for safely enjoying mozzarella and soft cheeses during pregnancy:
- Choose pasteurized cheeses from reputable brands at the grocery store or cheese shop.
- Avoid imported cheeses and unpasteurized soft cheeses unless they’ve been aged over 60 days.
- Heat deli-fresh mozzarella, Brie and Camembert until bubbly when cooking.
- Don’t eat mold-ripened soft cheeses like Brie or blues cheeses.
- Check labels carefully for warnings about unpasteurized cheeses.
Pregnant women are 10 times more likely to get listeriosis from contaminated foods. So it’s important to take extra precautions with higher-risk cheeses. But pasteurized mozzarella, cream cheese, paneer, ricotta and other soft cheeses are perfectly fine to eat during pregnancy.
As always, check with your doctor if you have any concerns about consuming cheese or other dairy products during pregnancy. But most health experts agree that pasteurized soft cheeses are a nutritious addition to the diet when enjoyed in moderation.
To summarize, nearly all mozzarella sold commercially in grocery stores in the U.S. has been pasteurized for food safety. Deli-fresh mozzarella may be raw but should display warnings if it’s unpasteurized. Authentic Italian buffalo mozzarella made according to old traditions is not pasteurized.
While pasteurization does subtly affect the flavor, texture and freshness of mozzarella, foodborne illness risks outweigh any small losses. And pasteurized mozzarella is perfectly safe for populations at higher risk like pregnant women. So while raw milk mozzarella may have marginal flavor advantages, pasteurization is crucial for minimizing food poisoning.