In this lab, you will be making ONE cultured dairy product. Cultured products are those that are fermented by bacteria. By-products of bacteria fermentation include flavors and lactic acid. Lactic acid reduces the pH of the milk, causing denaturation of milk proteins. The procedures below describe how to make sour cream, kefir, yogurt, and creme fraiche. However, given constraints you may have in purchasing ingredients, just choose the ONE that you are most interested in doing. You will need a warm environment (98 to 108 degrees Fahrenheit) for the fermentation. Otherwise, you may need to ferment for 48 hours.    

Sour Cream

  1. Add 1.5 cups heavy cream and 1.5 cups whole milk to a clean sterilized 32 oz jar
  2. Add 3/4 cup of cultured butter milk and mix
  3. Cover jar with a clean cloth and hold in place with a rubber band
  4. Store in a warm place for 24 hours
  5. Seal jar and refrigerate

Kefir

  1. Add three cups of whole milk to a clean sterilized 32 oz jar
  2. Add 1/4 cup of cultured kefir drink drink and mix
  3. Cover jar with a clean cloth and hold in place with a rubber band
  4. Store in a warm place for 24 hours
  5. Seal jar and refrigerate

Yogurt

  1. Add three cups of whole milk to a clean sterilized 32 oz jar
  2. Add 3 table spoons of plain yogurt and mix 
  3. Cover jar with a clean cloth and hold in place with a rubber band
  4. Store in a warm place for 24 hours
  5. Seal jar and refrigerate

Creme Fraiche 

  1. Add three cups of heavy whipping cream to a clean sterilized 32 oz jar
  2. Add 1/4 cup butter milk and mix 
  3. Cover jar with a clean cloth and hold in place with a rubber band
  4. Store in a warm place for 24 hours
  5. Seal jar and refrigerate

Lab Question

Observe the product you made. Describe its color, texture and taste. From your experience (if any), how much do you think it compares with the commercial product you would get from the store? Discuss any problems you may have encountered that affected the quality of the product, or how the product could be improved. 

Courtney Simons
Administrator
Courtney Simons is a food science professor. He holds a BS degree in food science and a Ph.D. in cereal science from North Dakota State University.
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