In the curdled milk, the protein present in the milk gets tangled, forming a solid mass and gets separated from the liquid which is known as whey. Sour smell and bitter taste also indicate towards spoiled milk. If the milk is spoiled naturally, then it may be caused due to the attack of microorganism, like bacteria or fungus and hence it is not good for health. Whereas artificial curdling is done with rennet, acid or with the help of useful microorganism. The products made from this process are not only used for delicious recipes but are also known for their health benefits.