How Do You Make Soured Cream?

The main ingredients required to make sour cream is 1 quart heavy sweet cream and 3 1/2 tablespoons cultured starter.

Sour cream is prepared from cream that is acted upon by lactic acid. This is mostly done with the help of bacteria, mainly Streptococcus lactis. When the cream is out in the open air, bacteria settle on the cream and commence mounting. But this is a very uncertain process as the bacteria which grow can make the cream distasteful or indigestible flavours. Instead you can use Freeze-dried packets of bacteria. You can also make use of buttermilk that consists of active bacteria.
To pasteurize, put the cream in a twofold boiler. Fill the base with water and boil. Keep the temperature of the cream up to 155 degrees and not over 160 degrees. Keep it for around 30 minutes at the same temperature. Cool the cream by bringing down the temperature to 65 degrees by immersing the vessel in ice water. Pour it in a quart-sized jar and close the lid firmly. Shake lightly for a few moments to carefully mix the starter throughout the cream. Keep it at a temperature amid 70 and 80 degrees for around 16 to 24 hours. After 15 hours, start tasting the cream. When it is acidic adequate, place it in the refrigerator and allow it cure for 24 hours.