Justasenging,
Those roots looked great before drying and as the others have suggested I bet it was the drying process you used (direct sunlight) that made the difference in the after drying results.
I dry my roots slow at room temp (around 72) in a room that has good air flow (over a air vent) and have them spread out thin on a couple of window screens.
It takes several weeks to dry completely but they always turn out good, stress rings, nice color.
The room I dry in does not even have any windows and if it did I would sure keep them away from direct sunlight while drying.
If you want to (need to) speed up the drying process, you can use a thermostat controlled forced air type heater (you can get small ones at walmart for 20-30 bucks) and have that blowing in the direction of your seng spread out on window screens.
Since the best time to sell seng is usually around Thanksgiving or just prior to Christmas there is really no rush to get it dry so I don't apply any heat to mine. The last that I harvest is usually mid to late October and it is usually nice a dry by Thanksgiving. If some of the larger roots were not quite dry yet I might consider applying some dry heat else I will just let them dry at room temp.
You should re-visit that same spot this year. Perhaps a few nice 3 or 4 prongs will be up this year that were not last year. You could try harvesting a few and dry them without sunlight exposure and find out for sureon that.
Best of Luck this year.
TNhunter