I would imagine you can use it in uncooked things b/c I see it listed a an ingredient in a lot of salad dressings.
Xanthan can indeed be used uncooked. For example, I thickened watercress pesto with a bit of xanthan gum powder in the vitamix today. It is just thick enough to paste a scallop seared with fennel pollen on a crostini. It will be finished with a grapefruit glaze. There are exact measurements for use on Modernist cooking. I free handed it in the blender until I was satisfied with its consistency however.
That's one of its main purposes--to thicken liquids and sauces without the need to heat or cook. Makes it easier to preserve the fresh quality of liquids.
Xanthan is cold soluble and does not require heat to gel. It comes from Xanthomas Campestris a close relative to slime mold... https://en.wikipedia.org/wiki/Xanthan_gum Luc H.