With condensation, as with distillation, differing compounds will surely condense at different temperatures. My belief is that at lower temperatures the creosote compounds have a higher tendency to condense onto the surface of cold meat, leaving a higher concentration of bitter compounds.
I'm sorry but this is a bit beyond my knowledge
. Although in the past I have successfully smoked at below zero temperatures without any bitter effects. However this is probably because I used the ProQ which only produces a small trickle of smoke and not enough for the meat/fish to gain a bitter outer layer.
Also, I remember camping in summer years ago and cooking our food on a pine wood fire. All our sausages were ruined by a bitter creosote-like taste even though it was warm and they were only cooking for a few minutes. Since then I've always associated the bitterness with using the wrong type of wood and over-smoking.
Tristar, I'm sure your knowledge in this area far exceeds mine however I have noticed that if the meat is colder than the smoking chamber then water condenses on the meat at first, It appears (to me) that this water then absorbs quite a lot of smoke before drying off and leaving small patches of slightly bitter flavours. To counteract this I just make sure the meat and smoking chamber are the same temperature.
Please note I am a relative newbie and I am happy to be corrected on any of these points
All the best
Ryan