Why doesn't feta cheese melt?
Whether a cheese will melt comes down to pH level, moisture, and fat content. Cheeses with neutral to low pH have a protein structure that is difficult to collapse. Feta will melt though, but you have to treat it like chocolate and melt over a pot of boiling water, adding a little bit of milk.
Goat cheese does not melt due to the presence of extra whey, which is a form of protein usually removed during the cheese-making process. The whey protein binds with the fat in the cheese and refuses to let go, thus maintaining the cheese’s texture and body even when heated.