Homemade Sour Cream From Starter

Sour cream is made from cream which has been acted upon by lactic acid. The most common way to get this lactic acid is through the action of bacteria, particularly Streptococcus lactis. When cream is allowed to stand exposed to the air, bacteria settle on the cream and begin growing. It is possible for the proper bacteria to grow, but it is more likely for the bacteria which grow to give the cream disagreeable or unpalatable flavors. Freeze-dried packets of bacteria are available. You can also use buttermilk with active bacteria.

If you are using freeze-dried bacteria, follow the directions on it to make a starter. You are looking for an acid level of at least 1 percent. It is more consistently successful if the cream is pasteurized before the culture is added.

To pasteurize, place the cream in a double boiler. Fill the bottom with water and heat. Bring the temperature of the cream up to 155 degrees F and not over 160 degrees F. Hold this temperature for 30 minutes.

Cool the cream to 65 degrees F by immersing the pot in ice water. Pour the cream in a quart-sized jar and add the culture. Close the lid tightly. Shake gently for a few moments to thoroughly mix the starter through the cream.

Keep the cream at a temperature between 70 and 80 degrees F for 16 to 24 hours. After 15 hours, start tasting the cream. When it is acid enough, put it in the refrigerator and let it cure for 24 hours.