Anonymous Modernist 12008

Is there any ingredient I could add to the rub that would make it less mobile at higher temperatures? Xanthan Gum? Something like that maybe?

Thanks, yeah, the more I think about it, the more likely it is I'm suffering a physical problem rather than an ingredient breakdown problem, I just wanted to make sure I wasn't missing anything obvious. I'm trying to avoid doing as much faffing after cooking as possible (I regularly get talked into cooking for 50+ people), but I have a few other things I think I can try to keep the flavor in there.

I apologize if this is a dumb question. I regularly cook pork ribs sous vide for extended periods of time (24 hours @ 150F+), I tend to use a rub that includes a fair amount of sugar (I have tried a few different kinds), but I've noticed that when cooked for that length of time that I lose a lot of (ie. almost all of) the sweetness. The heat (cayenne, various types of chili pepper) tends to mitigate a lot as well, but the pungent spices (pepper, celery seed... especially the damned celery seed) tend to stick around pretty well. Is this a common problem? Is there a particular type of sugar that tends to survive high temperatures for an extended duration or is there a fundamental concept that I'm missing? Thanks.