Up until somewhere in the Key stages of the game (depends on game setting), they initially turn blue when the energizer is eaten, then blink blue/white when they are about to revert to their individual color. Some of the stages just prior to the Key stages, they only blink as there is no time of full blue.

In those Key stages, they only reverse direction and never change color.

White is not a good choice to have available with this particular question; especially as written.