Question

if we add buttermilk to luke warm

Answer 1

hello friend,Buttermilk is made from curd. Usually if curd is added to milk, then it also changes to curd due to action of bacterium Lactobacillus. So, the same process would have taken place if buttermilk is added to milk. But here the milk is chilled, so at this temperature growth of Lactobacillus is prevented, so no formation of curd takes place but when chilled milk comes to normal room temperature, it will become curd.
hope it helps u

Answer 2

The following are the observations we notice when we add buttermilk to chilled milk :

1.The milk will not change to curd because - butter milk contains Lactobacillus bacterium (which converts milk to curd) which cannot multiply or grow in that cool temperature.(if it grows then only milk will change into curd)

2.Some situation its changes into curd but not completely(because of affect of external temperature)

If the same buttermilk add into the lukewarm milk then with in 5-6 hours you observe that milk changed to curd because of favorable temperature for growth