Two chilies I regularly use in my cooking:
50,000-100,000 Scoville units
100,000–350,000 Scoville units
The Scotch is basically hotter, potentially a lot hotter than the bird’s eye. Here’s the thing though: I find the bird’s eye to burn a lot differently, whether eaten raw OR after used in cooking. In either case, I’m talking about mincing or pureeing the chilies and cooking them thoroughly as part of a dish. In such a case, one would think that the burn would be entirely up to the Scoville units–it’s all the same capsaicin, right?–but in my experience this is not the case.
The bird’s eye burn is harsher, stronger, bitchier. I call it a “front burn”: it tends to burn the tip of the tongue and get under the tongue, too. It’s a pretty painful burn, but I like it. I also love the flavor of the bird’s eye, and I use it in Thai and Indian dishes.
The Scotch bonnet burn is totally different. I call it a “back burn” as it seems to radiate from back in the throat. It does not burn the tip of the tongue much. (I’m talking about using it in a cooked dish. All bets are off if you eat one raw. I’ve tried pieces, and the “back burn” still seems to apply.)
So, the question is this: If you agree that such a thing is possible, what could account for the different burn “styles”?
My best guess is that the capsaicin is “packaged” differently in the two types of chili and somehow relates to slightly different mucus membranes differently. What do you think?