Question

How does cheese spoil?

Answer 1

Cheese: It smells like sour milk.

If you spot mold on hard cheese, it's generally safe to cut off the moldy part and eat the rest, since the spores likely will not have spread throughout the cheese. Another sign that cheese has gone bad is a smell or taste of spoiled, sour milk.

Answer 2

Microbiological spoilage of cheese is one of the important reasons that render the nutritious and tasty cheese not only inedible but also a potential source of infection. The spoilage may be due to bacteria or fungi. The defect due to contamination may arise from the surface of the cheese showing visual and organoleptic changes or it may be hidden internally.