Cheese cultures explained — what starter cultures are, the difference between mesophilic and thermophilic, and how home cheesemakers use them.
Cheese cultures are a key ingredient in many cheeses, developing flavor and acidity. For home cheesemakers, understanding cultures is important. Here's a guide to cheese cultures explained for home makers.
What Cheese Cultures Are
Cheese cultures are specific beneficial bacteria added to milk in cheesemaking. They ferment the milk's lactose (sugar) into lactic acid, which acidifies the milk — important for coagulation, flavor, texture, and preservation. Cultures also contribute to the cheese's flavor development as it ages. So cheese cultures are the bacteria that ferment and acidify the milk, developing flavor and aiding cheesemaking. While simple acid-set cheeses (like ricotta, paneer) don't use cultures, many cheeses (especially cultured and aged ones) rely on them. Understanding cultures helps home cheesemakers make a wider range of cheeses with proper flavor and texture.
What Cultures Do
Cultures play several roles. They acidify the milk (fermenting lactose to lactic acid), which lowers the pH — important for rennet to work well, for the curd's texture, and for flavor. They develop the cheese's flavor, as the bacteria and their byproducts contribute taste during aging. And the acidity helps preserve the cheese and control unwanted microbes. So cultures acidify, flavor, and help preserve the cheese. The acidification is essential for many cheeses' coagulation and texture, while the flavor development is key to aged cheeses' character. Cultures are thus central to making cultured and aged cheeses (as opposed to simple acid-set fresh cheeses).
Mesophilic vs. Thermophilic Cultures
The two main types of starter culture are distinguished by their temperature preference. Mesophilic cultures work at lower (moderate) temperatures and are used for cheeses made at lower temperatures — like cheddar, Gouda, chèvre, and many soft and semi-hard cheeses. Thermophilic cultures work at higher temperatures and are used for cheeses made at higher temperatures — like many Italian cheeses (mozzarella, Parmesan) and Alpine cheeses (Gruyère). So mesophilic cultures suit lower-temperature cheeses, thermophilic cultures suit higher-temperature ones. Choosing the right type for your cheese is important, as each works best in its temperature range. Recipes specify which to use.
Other Cultures and Molds
Beyond starter cultures, some cheeses use additional cultures or molds for specific characteristics. Blue cheeses use Penicillium roqueforti mold (for the blue veins); bloomy-rind cheeses use Penicillium candidum (for the white rind); washed-rind cheeses use bacteria like Brevibacterium linens (for the orange rind and pungency); and Swiss-style cheeses use propionic bacteria (for the holes). These specialized cultures and molds, added along with the starter, give particular cheeses their distinctive features. So beyond the basic starter, specific molds and bacteria create blue veins, bloomy rinds, washed rinds, and holes. Home cheesemakers add these for the relevant cheese styles.
Using Cultures at Home
For home cheesemaking, cultures are available from cheesemaking suppliers (often as freeze-dried powders) in the various types (mesophilic, thermophilic, and specialized molds/cultures). To use them, you add the specified culture to the warmed milk and let it ripen (ferment) for a time before adding rennet, allowing the bacteria to acidify and flavor the milk. Follow your recipe for the type and amount. As an alternative for some cheeses, cultured buttermilk or yogurt (containing live cultures) can act as a starter. So home makers add the appropriate freeze-dried (or alternative) culture to the milk, letting it ripen, per the recipe. Cultures are easy to use once you have the right type for your cheese.
Frequently Asked Questions
What are cheese cultures?
Specific beneficial bacteria added to milk in cheesemaking that ferment lactose into lactic acid, acidifying the milk and developing flavor, texture, and preservation — key for cultured and aged cheeses.
What's the difference between mesophilic and thermophilic cultures?
Mesophilic cultures work at lower temperatures (for cheeses like cheddar, Gouda, chèvre); thermophilic cultures work at higher temperatures (for cheeses like mozzarella, Parmesan, Gruyère). Use the type your recipe specifies.
Do all cheeses need cultures?
No — simple acid-set fresh cheeses (ricotta, paneer) don't use cultures, while many cultured and aged cheeses rely on them for acidity and flavor. Recipes specify whether cultures are needed.