Are Soft Cheeses Fermented? The Science Behind Your Favorite Creamy Cheeses

December 23, 2025 •

5 min read

Over one-third of the milk produced annually in the United States is consumed as cheese, a product with a history stretching back thousands of years. The vast world of cheese offers a wide range of textures and flavors, from aged Parmesan to delicate, creamy soft cheeses. But what is the process that gives soft cheeses their unique characteristics, and are they truly fermented?

Quick Summary

Soft cheeses use fermentation, but not all are ripened by microbes; some, like fresh varieties, rely on simple acidification. The distinct flavors and textures of soft cheeses depend on the specific cultures, aging methods, and moisture content involved. Fermentation creates lactic acid, which is crucial for forming the curd and preserving the cheese.

Key Points

Fermentation is core to cheesemaking: Most cheese production, including that of soft cheeses, uses fermentation to convert lactose to lactic acid, initiating the curdling process.
Not all soft cheese is ripened: Fresh soft cheeses undergo minimal fermentation and are consumed young for a mild flavor, while ripened ones are aged for flavor complexity.
Brie and Camembert ripen externally: Bloomy-rind cheeses like Brie use surface molds like Penicillium camemberti to ripen from the outside-in, creating their creamy texture and distinctive flavor.
Washed rinds intensify flavor: Some soft cheeses, like Limburger, are washed with brine to encourage specific bacteria, resulting in a stronger, more pungent taste and aroma.
Acid-set cheeses are different: Fresh soft cheeses such as Ricotta are made by direct acidification with heat, bypassing the microbial fermentation process entirely.
Microbes may not be active in the final product: While fermentation is key, some cheeses are heat-treated or aged in ways that reduce or eliminate live cultures in the final product.
Feta is a fermented, brined cheese: Feta cheese is fermented with lactic acid bacteria and then aged in brine, which imparts its signature tangy and salty profile.
Mozzarella production can vary: Mozzarella can be made with or without a full fermentation, with traditional cultured varieties using a starter for a deeper flavor.

Fermentation: The Foundation of Most Cheeses

Fermentation is a core process in cheesemaking, converting lactose (milk sugar) into lactic acid and other compounds through the action of microorganisms. This acidification is a key step, causing the milk proteins to coagulate into a solid gel, or curd. For most soft cheeses, both fresh and ripened, this microbial activity is essential for creating the initial curd and developing the final flavor profile.

The Role of Bacteria in Soft Cheese

Lactic acid bacteria (LAB) are the primary cultures used in soft cheesemaking. Mesophilic cultures, such as Lactococcus lactis, thrive in moderate temperatures and are used for many common soft cheeses. These bacteria acidify the milk, which helps the curds form and aids in preservation. In some ripened soft cheeses, other microorganisms are introduced to develop further complexity. For instance, in Brie and Camembert, surface molds like Penicillium camemberti and yeasts are crucial for ripening and flavor development.

The Ripening Process: Where Fermentation Gets Complex

While all soft cheeses involve some form of fermentation, the difference between fresh and ripened soft cheeses lies in the affinage, or aging, process. Fresh soft cheeses, like ricotta or paneer, undergo minimal fermentation and are not ripened, giving them a mild, milky taste. Ripened soft cheeses, on the other hand, are aged for weeks to allow microbial activity to mature and develop complex flavors, aromas, and textures.

The Aging of Bloomy Rind Cheeses

Exterior Fermentation: Soft-ripened cheeses like Brie and Camembert have a characteristic white, bloomy rind. This is due to the growth of a special surface mold, Penicillium camemberti, introduced after the curds are formed.
Ripening from the Outside-In: This mold creates a protective layer that allows the cheese to ripen from the rind toward the center, resulting in a gooey, creamy texture on the outside and a firmer core.
Enzymatic Activity: The enzymes produced by the mold and other microbes break down proteins and fats, which contributes significantly to the cheese's signature flavor and aroma.

The Creation of Washed-Rind Cheeses

Brine or Liquid Wash: Cheeses like Limburger have their rinds regularly washed with a saltwater brine or other liquid, which encourages the growth of specific bacteria, notably Brevibacterium linens.
Intense Aromas and Flavors: This process results in a reddish-orange rind, a more pungent aroma, and stronger, more savory flavors compared to bloomy-rind varieties.

Comparison: Fermented vs. Acid-Coagulated Soft Cheeses

Not all soft cheeses rely solely on microbial fermentation. Some fresh soft cheeses, like Ricotta, are produced primarily through the direct addition of acid and heat, causing the milk proteins to coagulate instantly. Other cheeses, like Mozzarella, can be made using either a fermented culture or a quicker, acid-set method.


Feature	Fermented Soft Cheeses (e.g., Brie, Feta)	Acid-Coagulated Soft Cheeses (e.g., Ricotta, Paneer)
Coagulation Method	Lactic acid produced by starter cultures, sometimes supplemented with rennet.	Direct addition of an acid (e.g., vinegar, citric acid) and heat.
Ripening/Aging	Often aged for weeks, allowing microbial activity to develop complex flavors.	Typically unripened and consumed fresh, resulting in a mild flavor.
Key Microbes	Starter cultures like Lactococcus lactis and surface microbes such as Penicillium camemberti.	Coagulation is primarily chemical, though some starter cultures might be used.
Flavor Profile	Ranges from mild to strong, earthy, or pungent, depending on the specific microbes and aging.	Mild, milky, and fresh, with the primary flavor coming from the milk itself.

The Science of Feta and Other Fermented Soft Cheeses

Feta cheese is a prime example of a fermented soft cheese. It is traditionally made from sheep's milk or a mix of sheep and goat's milk, where lactic acid bacteria are added to ferment the milk. The brining process, in which the cheese is aged in a saltwater solution, is another critical step that enhances its signature tangy, salty flavor and crumbly texture. The aging time and temperature influence the acidity and overall flavor profile.

Conclusion: The Short and Long of Fermentation

Ultimately, the question of whether soft cheeses are fermented is best answered with a distinction between different types. Almost all cheesemaking, including that of many soft cheeses, begins with a fermentation step to curdle the milk. However, fresh soft cheeses see this process stopped early for a mild flavor, while ripened soft cheeses undergo further, more complex fermentations involving various bacteria and molds to achieve their distinctive, mature tastes and textures. The variety of microorganisms and production methods is what makes the world of soft cheeses so diverse and fascinating. For a deeper dive into the technical details of soft cheese microbiology, the National Institutes of Health (NIH) bookshelf offers an extensive resource on the topic.

Is Feta cheese fermented?

Yes, Feta cheese is fermented using lactic acid bacteria, which gives it its characteristic tangy flavor before it is aged in a brine solution.

Is Mozzarella cheese fermented?

Mozzarella can be fermented, and traditional cultured mozzarella relies on a longer, slower fermentation with specific bacterial starters to develop more flavor. Quick versions can also be made using direct acidification, bypassing a prolonged fermentation.

What is the difference between fresh soft cheese and ripened soft cheese?

Fresh soft cheeses undergo minimal fermentation and are not aged, resulting in a mild, milky taste, while ripened soft cheeses are aged for weeks to allow microbes to develop complex, pungent flavors and aromas.

How does fermentation create the creamy texture in Brie?

In Brie, the surface mold Penicillium camemberti on the rind releases enzymes that break down proteins and fats, causing the cheese to ripen from the outside-in and develop its signature gooey, creamy texture.

Do all cheeses contain live active microbes?

No, not all cheese contains live active microbes. While fermentation is a crucial step in production for all cheese varieties, some processes, like heat treatment or pasteurization, can kill off the live cultures.

What are bloomy-rind soft cheeses?

Bloomy-rind soft cheeses like Brie and Camembert get their soft, edible white rinds from the growth of molds, typically Penicillium camemberti, which are added during the cheesemaking process.

Are acid-coagulated cheeses fermented?

Soft cheeses produced by direct acid and heat coagulation, such as Ricotta or Paneer, are not fermented by microorganisms in the traditional sense; their curd formation is a chemical, not biological, process.

Frequently Asked Questions

Not necessarily. While fermented cheeses do contain probiotics during their production, the final product's live microbial content depends on the aging and pasteurization processes. Some heat treatments or specific aging methods can kill off these beneficial bacteria.

Cottage cheese can be considered lightly fermented. It is often made using a mild starter culture that creates lactic acid, which helps to coagulate the milk. This process is typically stopped early, as Cottage cheese is a fresh, unripened cheese.

Yes, many recipes for soft, cultured cheeses like cottage cheese or fresh chevre use a starter culture and can be made at home. Starter cultures can be purchased, or you can sometimes use natural starters like clabber or whey.

Yes, fermentation reduces lactose content as the lactic acid bacteria consume it for energy. This can make many fermented cheeses easier to digest for people with lactose intolerance, although the exact amount of remaining lactose varies.

Generally, fermented soft cheeses that have been ripened, like Brie or Camembert, will have a more complex, earthy, or pungent flavor. Acid-set cheeses like Ricotta or Paneer will have a milder, more delicate milky flavor.

The pungent aroma of some fermented cheeses, particularly washed-rind varieties like Limburger, is caused by specific surface bacteria such as Brevibacterium linens. These microbes produce volatile compounds that contribute to the strong smell.

Yes, cream cheese is typically made by fermenting a mixture of milk and cream using a lactic acid starter culture. The process results in the characteristic tangy flavor and spreadable texture of cream cheese.