Activating a Mesophilic Yogurt Culture (Viili, Matsoni, Filmjölk, Piima)

Viili, matsoni, filmjölk, and piimä are traditional Nordic yogurts known as “mesophilic”. This means that these cultures thrive at moderate temperatures.

Unlike regular yogurts, which require more heat, mesophilic cultures (or strains) can be prepared at room temperature, without a yogurt maker.

This guide provides step-by-step instructions for rehydrating and activating a mesophilic yogurt culture. Follow it to successfully make your first long-lasting, delicious yogurt recipes, which you can then back-slop for multiple recipes.

Note that dehydrated yogurt culture, although it retains its properties for a very long time, requires prior activation.

  • Preparation time: 5 minutes
  • Fermentation: 48 hours
Activating a mesophilic yogurt culture

How to Start Activating a Mesophilic Yogurt Culture (Viili, Matsoni, Filmjölk, Piima)

Have you just bought a mesophilic yogurt culture such as viili, matsoni, filmjölk, or piima? Great news! These Nordic yogurts are easy to prepare at room temperature, without a yogurt maker. Follow our instructions to activate your ferment and quickly enjoy your homemade yogurts!
No Ratings
Preparation Time 5 minutes
Fermentation Time 2 days
Course Dessert


  • 1 bag or capsule of mesophilic yogurt culture
  • 1 500 ml glass jar
  • 250 ml of fresh pasteurized whole milk
  • 1 Tablespoon



  • Add the contents of the entire capsule or sachet of mesophilic ferment to the jar, along with a tablespoon of milk.
  • Stir to break up any lumps.
  • Add the rest of the milk.
  • Cover the jar with the cloth and rubber band or lid.
  • Let it ferment at room temperature.

After 24 hours

  • This first recipe, and your next 2 to 5, will probably be liquid. This is to be expected!
  • Trust your senses! If the taste and smell (and subsequently the texture) are satisfactory, it's because your mesophilic ferment has been reactivated. Keep your yogurt in the fridge for 6 hours before eating it. In the meantime, learn how to make your next recipes.
  • If the texture is not satisfactory, take a tablespoon of yogurt and start a new recipe with it. Continue making recipes every day until you get the texture you want.


Well done! The yogurt you've just made can be used as a base (also called a "starter") for your next recipe. Keep one tablespoon for every 250 ml of milk for your next recipe. This is called back-slopping. So, for a 1 litre recipe, keep 4 tablespoons.
Have you tried it?Share and tag @revolutionfermentation!

Note: Our viili and matsoni cultures contain three capsules. Only one is needed per recipe. Store the remaining capsules of mesophilic strains in the freezer. You will only need to use a new capsule when the previous one loses its effectiveness and no longer ferments.

More details in the recipe for mesophilic yogurts.

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