Be sure to check the expiration date on the buttermilk when you purchase it. (Psst! Reach to the back of the dairy case for the freshest carton you can find.) It is important that you have live cultures in your starter. For best results the date should be two weeks out. Cultures tend to sink to the bottom, so be sure to shake well before measuring.
1 cup very fresh commercial buttermilk, well shaken
1 cup instant nonfat dry milk powder
lukewarm water
Quart jar with non-metal lid
Put milk powder in a liquid measuring cup and add lukewarm water to equal 3 cups. Stir to dissolve. Pour into a quart jar, add commercial buttermilk and stir until combined.
Set jar, uncovered, in a warm, protected spot in the kitchen for 12 – 24 hours, until thickened. Do not disturb while culturing or it will not set. If your kitchen temp is below 70 degrees you will need to look for a warm spot elsewhere. Some ideas: on top of the water heater, on top of the fridge, a warm cupboard.
 |
| After 12 hours gently tip jar to determine if buttermilk is set and ready to chill. |
Mark date on jar, refrigerate, and use within a week to 10 days. Reserve 1 cup Kitchen-Cultured Buttermilk to start a new batch within 1 week.
*Variation: Substitute 3 cups milk, warmed slightly to 80 degrees F, for nonfat dry milk powder and water.