Question

What will happen if you add buttermilk to chilled milk?

Answer 1

    Normally if buttermilk is added to warm milk or milk at room temperature, milk gets fermented by bacteria.  It takes a few hours for the milk to become yogurt. 

   If buttermilk is added to chilled (cold) milk, then the fermentation of lactic acid by bacteria lactobacillus takes a longer duration. The process is very slow when the temperature is below room temperature.  Milk retains most of its nature and taste.

Answer 2

If we add buttermilk to chilled milk then the result will be very sour in taste