Directions

1. 1

   Pour the milk into a clean glass jar or container. You may gently warm the milk to room temperature (around 70°F) if it comes directly from the refrigerator, as this helps activate the fermentation process more efficiently, though room-temperature milk works fine as well.

2. 2

   Add the buttermilk culture (store-bought buttermilk or activated dried starter) to the milk. If using dried starter, follow the packet instructions for proper activation beforehand.

3. 3

   Stir the mixture gently with a clean spoon until the culture is evenly distributed throughout the milk.

4. 4

   Cover the jar loosely with a lid or cloth (do not seal tightly, as fermentation produces gases). Leave the jar at room temperature (ideally between 68–75°F) away from direct sunlight.

5. 5

   Allow the buttermilk to ferment for 8–12 hours, or until it reaches your desired thickness and tanginess. The longer it sits, the thicker and more sour it becomes. Taste after 8 hours and continue fermenting if a stronger flavor is preferred.

6. 6

   Once fermented to your liking, stir the cultured buttermilk and transfer to the refrigerator. It will continue to thicken slightly as it chills and will keep for up to 2 weeks when properly sealed.