I’m not sure, but they do sell some pre-hydrated gums and usually call them “perfected”. They are largely buying in commercial quantities and re-packaging for restaurant-scale use with their gums because a lot of the bigger ingredient companies that make the best products won’t sell in smaller than 50 lb (or sometimes even much larger) increments.

Pre-hydrated gums are usually just hydrated and then spray dried ones.

I've used their "perfected" xanthan gum which is a separate SKU from their regular xanthan gum. At least for gum arabic they seem to only offer one SKU, so I'm guessing it's not prehydrated.