wrong rotation in animation per script

Sometimes unity connects two keyframes of a rotation animation in a wrong way: instead of using the shortest degree change it will make a fast flip around the axis. We've found a way to solve this by clicking in the animation editor at the corresponding curve first from "Interpolation->Quaternion" to "Interpolation->Euler Angles" and then back to "Interpolation->Quaternion". After that every rotation looks fine. Is there a way to set the interpolation per script or to avoid the problem in another way?