How to Make Cultured Buttermilk

Two Methods:Making Buttermilk With a StarterMaking Buttermilk From Scratch

Buttermilk is great in the kitchen - not only for baking but for drinking straight out of the glass. It is slightly thicker than milk, and not as heavy as cream. Instead of buying buttermilk at the grocery store, you can easily make it yourself following these steps.

Method 1
Making Buttermilk With a Starter

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    Add a bacterial starter of 6 to 8 ounces/180-235ml of active fresh cultured buttermilk to a clean quart jar. Use 6 ounces/180ml if you are certain of the freshness of the starter. When in doubt, use a full cup of buttermilk as starter.
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    Fill the rest of the jar with fresh milk.
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    Screw the lid on securely. Shake thoroughly to mix. Label it with the date.
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    Let it sit out in a warm part of the room until thickened, which should take about 24 hours. If you find it takes longer than 36 hours, the starter was no longer active (the bacteria had died). The buttermilk may or may not be tasty if it takes longer than 36 hours but it can still be used for baking.
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    Check to make sure the thickened buttermilk coats the glass. This happens because the bacteria have fermented the milk, and the lactic acid is causing the milk proteins to thicken. Refrigerate immediately

Method 2
Making Buttermilk From Scratch

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    Allow a cup of filtered fresh raw milk to sit covered at room temperature until it has thickened. This usually takes several days.
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    Place 1/4 cup of the thickened milk in a pint-sized mason jar.
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    Add a cup of fresh milk (it doesn't have to be raw at this point), cover, shake to mix, and allow to sit at room temperature until thickened again.
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    Repeat this transfer of sub-culturing several more times until the milk dependably thickens in a 24-hour period. Taste a small amount to confirm that it is tart, thickened, and has no off flavors (e.g. tart but not bitter).


  • Sour cream can be made with the same procedure as buttermilk, using one cup of cream mixed thoroughly with 2 tbsp fresh active buttermilk and letting it sit for 12-24 hours at room temperature. The higher butterfat in the cream, the thicker the finished sour cream.
  • Buttermilk keeps easily for weeks in your refrigerator. If you keep it longer, it may develop mold on the inner walls of the jar. This mold belongs to the same group of fungi which grow on cheese and is not dangerous. Remove it and the buttermilk can still be used for baking.
  • The acidity of buttermilk explains its long refrigerator shelf life. Acid is a natural preservative because it inhibits the growth of pathogenic bacteria.
  • Fresher buttermilk makes better starter for cheese.
  • Because much of the lactose has been broken down to lactic acid, buttermilk should cause less of a problem for those who are lactose intolerant.
  • Buttermilk pancakes and waffles cook up light and fluffy, so add it to the batter. Use it also when baking cakes.
  • To make a gallon of buttermilk, add 1 quart buttermilk to 1 gallon (3.8 L) of fresh whole milk and pour into a large container. Mix, and pour back into the original containers. The next day, the entire five quarts will be nicely thickened.


  • Check the label on the bottle you buy at the store. It needs to say cultured buttermilk, and make sure it is not out of date, as bacteria die down over time.

Things You'll Need

  • 6-8 ounces/180-235ml active cultured buttermilk
  • 3 cups whole milk or 2% or skimmed
  • Very clean 1 quart container with secure lid. Mason jars work well.

Sources and Citations

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