To blanch is to turn pale, usually as the result of a physical or psychological shock. Nineteenth century literary heroines were frequently blanching — before they fainted, that is.
Blanch has also taken on the more general meaning of to cause shock in general. A government can blanch at following through a particular reform, without the implication that an entire cabinet actually turned white. You can blanch an inanimate object, too, when you deprive it of its natural color. White toilet paper has been blanched by using bleach, for example, though environmentalists blanch at the thought.