Toasting many spices,and heating some peppers increases and brings out the spice and heat. Other foods, such as onions, shallots and garlic (yes, I know they're from the same family; just can't think of other examples right offhand), it mellows their bite.
Is there something scientific to this? It doesn't seem to be component specific, as capsaicin is the main heat element in peppers, but some, such as jalapenos, actually seem to mellow a bit with roasting. Unless the ones I've roasted were just randomly mellower like jalapenos from even the same plant can vary anyway?
I understand the pepper itself doesn't actually get hotter; cooking just releases some of the capsaicin oils. But why would it affect other foods the opposite way, and how would peppers even vary in how they respond to cooking heat?