When milk goes sour, what type of change has happened?
a. physical only
b. chemical only
c. physical and chemical

C! Sometimes, when you pour your milk, it may come out as a cottage-cheese like texture and it may smell really bad. Also, When the amount of lactic acid in the milk begins to increase, the pH drops and the casein molecules begin to clump. The high levels of lactic acid are also what give spoiled milk its characteristically sour smell. Hope this helped!