That I don't know. Perhaps someone will chime in & help you w/that.
I do remember reading something about alcohol burning off with heat. I'm not exactly sure though.
I would imagine it's part of the "vehicle" that flavors need to get from point A to point B or something like that.
You might want to post something in the "DIY" section. Those are the people in the know.
Sorry I couldn't be of any more help.