You will need
    • milk;
    • the bottle is plastic.
Take 0.5 liters of milk (best milk of 2.5-3.5% fat, can be used both store-bought and homemade), pour it into a pan and bring to a boil. Be sure to remove the foam.
Pour in a thermos of boiling water to the top, close it, and leave at least 15-20 minutes. Dip a sterile thermometer in the pan with the milk, wait until, until the temperature of the milk drops to 40-45 degrees. Sterilize the thermometer with rubbing alcohol or lower it a probe in a kettle and let it writing a rolling boil for a few minutes. Pour the boiling water from a thermos and wait until the flask is well cooled.
Open a bottle of plastic, (make sure it has no external damage. In a bottle pour a little milk 40-45 degrees. Thoroughly shake. In a pot of milk, pour the content of vial and stir with a sterile spoon (should be sterilized for at least 2 minutes). Pour all in a thermos or jar and close the lid. If instead of a thermos was used by the Bank, it must be wrapped in a warm blanket and put on 12 hours in a warm place (during the heating season - on the battery or near it, in the warmer time of year - put on the window located on the Sunny side).
After a time, pour the starter culture into the jar (be sure sterilized) and put in the fridge. If cooking Narine was used by the Bank, the leaven put in the fridge in it, not pouring. After 2 hours, the leaven Narine ready to to do her fermented milk drink plastic or perhaps yogurt or cottage cheese.