Has anyone ever had a Hershey bar? It is the vilest chocolate you could ever taste. Awful!
It's made from sour milk actually. Due to the longer distances required in the US to transport milk, it would get sour before it was made into chocolate, whereas Europe has shorter distances and the milk kept.
Nowadays it's easy to keep the milk for longer periods, but most Americans are used to the taste so the companies have kept the taste by adding butyric acid.