Okay, maybe it only happens to me...but when I buy precut carrots, they seem to turn white, very quickly!
Found an easy and quick solution - put them in water! Put carrots in a bowl, cover with cold water, and place in fridge. I would drain the water when we ate dinner, and whatever carrots we didn't eat, was covered again!
So, don't throw out those carrots! Rehydrate them!