$3.99 Flat Rate Shipping* Click here for details

Overview of Cheese Cultures: Thermophilic and Secondary Starters


As mentioned in the first part of this series, cheese cultures are specialized strains of bacteria classified by their uses and personalities. Some of the categories of cultures include thermophilic, non-dairy, and secondary cultures.

Thermophilic culture works at an optimum temperature of 108° to 112°F.

Thermo B

Containing Streptococcus thermophilus and Lactobacillus delbrueckii ssp. Bulgaricus, this strain is more proteolytic (breaks down proteins) than S. thermophilus alone. It is used in hard, soft and semi-soft cheeses.

Thermo C

Containing Streptococcus thermophilus and Lactobacillus helveticus, Thermo C culture is used in a lot of Italian-style cheeses, such as Romano, provolone and Gruyère.

Secondary Cultures are mold, yeast, enzyme, and bacterial powders that are used in bloomy rind, washed-rind, or smeared-rind cheeses. These cultures are either added to the milk between layers of curds, or applied to the surface of the finished cheese. Sometimes one cheese calls for two or more kinds of secondary culture.

Brevibacterium linens, requiring a high pH reading for successful growth, creates a red-orange mold rind on washed- or smeared-rind cheeses.

Geotrichum candidum is a rapid-developing mold that overpowers unwanted mold on moist cheese. There are a few variations on this strain: Geo 13 produces intermediate flavors, Geo 15 is a bit milder, and Geo 17 creates the lightest, mildest flavor.

Penicillium candidum (also called penicillium cambembertiproduces a white, fuzzy mold on the surface of the cheese. There are many different strains of this bacteria, having strong to mild properties. They include ABL, HP6, Niege, SAM3, and VS.

Penicillium roqueforti creates colored veins and streaks in cheeses such as blue, gorgonzola, Roquefort and Stilton. Different kinds of this secondary culture are used to achieve different colors, from blue to gray to green.

Propionic bacteria are used for eye formation, aroma, and the addition of nutty or buttery flavors to cheeses like Swiss.



Each culture producer will have different culture blends with varying personalities and properties, so you can ask your culture provider if you have any specific questions about the blend of cultures you will be purchasing. Ingredient lists are usually readily available, and making sure you know what is in your cultures will help you to understand what your finished cheese will be like and will also help you with any troubleshooting. 

Platter of Homemade Cheese

Related Articles & Recipes


Related Products

Feta Starter Culture
Cheese Starter Cultures
Liquid Vegetable Rennet Vegetable Rennet
Feta Mold with Brining Container Cheese Shaping Molds

Free eBook Library Access & Weekly Newsletter

Sign up today for free access to our entire library of easy to follow eBooks on creating cultured foods at home, including Lacto-Fermentation, Kombucha, Kefir, Yogurt, Sourdough, and Cheesemaking.
  • Library of eBooks for making your own cultured foods
  • Weekly newsletter filled with tips & tricks
  • Expert advice articles, recipes, and how-to videos
  • Join 180,000+ other health-conscious readers
  • We never share your information!
first name last name email address

Updating your cart...