As the surface stretches, certain regions become thinner.
These exposed areas can lose moisture relatively quickly.
Once a surface becomes sufficiently dry and hot, browning reactions can occur more readily.
The top of a blister may therefore develop a darker color than the surrounding cheese.
The Maillard reaction
One important process responsible for browning is the Maillard reaction.
This is a series of chemical reactions involving certain sugars and amino compounds when food is heated.
It contributes to the appealing colors and complex flavors of many cooked foods.
Think of toasted bread, roasted potatoes, or the browned exterior of certain baked dishes.
Cheese can undergo related browning reactions when the right conditions are present.
However, the intensity depends on the cheese's composition, including the amount of available sugars and amino compounds.
ScienceDirect+1
Are brown spots always desirable?
A little browning can add flavor and visual appeal.
