How can I rotate smoothly in moving with iTween?

Hello, developers.

I’ve noticed iTween, one of the Unity3D’s great plugins.
I used code like below.

iTween.MoveTo (gameObject, iTween.Hash ("path", path, "movetopath", true, "orienttopath", true, "looktime", .6 , "time", 10, "speed", speed, "easeType", _easeType, "loopType", _loopType ));

At first, I was very glad that the object moves smoothly along what I set the course.

But, sometimes when it turns at the corner such as rotating 90 degrees, or doing U-turn, it rotates its face so fast that it looks so weird and unnatural.

I thought that when the rotation is changed, if I adapt the object with Quaternion.Euler or Quaterion.Slerp, the problem would be solved.

However, those doesn’t seem to work.

In short, I like that the object faces forward oriented to path, but it rorates so fast. Is there any method to solve that?

Thanks for reading my problem.

use this

iTween.RotateAdd(gameObject, iTween.Hash("amount", rotation, "time", animationTime, "easetype", iTween.EaseType.linear, "looptype", iTween.LoopType.none));

where rotation is in Vector3, animationTime is in float