Sometimes, I just need to put a question out there...
There is always a reminder that, no matter how much you learn or what your experiences are, things can sometimes behave in a way that is totally unexpected. I've used xanthan a thousand times alone and synergistically with other hydrocolloids and dispersed it many ways. I realize that it has emulsifying properties, but almost always it's use is intended to thicken a water-based solution (except when boosting the powers of other additives and starches).
Then for a VIP table during lunch, I planned on quickly thickening some clear tomato water to add as an element to an amuse featuring fresh mozzarella, duck salami, and basil. Instead of getting thicker, the tomato water immediately began to hold air... so much to the point that it became a very light fluffy whip which remained stable for hours afterwards (all with a very small percentage of xanthan, I might add).
The texture was slightly of xanthan, but not so gummy as a methocel whip.
What was the variable in the tomato water that catalyzed this outcome?