Multiple rotations with Quaternion Slerp problem

I'm having a problem with the Quaternion.Slerp function. Basically, I have a rotating cylinder. When the player presses a key, the cylinder has to slow down to a certain value (which is calculated on the moment the key is pressed)

The fact is that the cylinder has to slow down (or rotate) a couple of more rounds untill it stops at the right value. With the Slerp, if the delta of the rotation is < 180, it will always spawn to the rotation closes to the current.

Now, my question is, how can I manage the rotations on a better way, since the Quaternion rotation values are wrapped between 0 and 360.