Rotate vertex around the direction of its curve


I’m emitting particles along a curve that curls in all directions. The problem I have is that at one point, the particles make a looping where they shouldn’t (see pic./blue). I guess its because the curve itself has become twisted. So I’m trying to unravel this ‘twist’ by rotating each vertex as of that point (see pic./green), around the axis of the curve. I can rotate the vertici easily along the xyz-axes by pressing those keys, but how do I rotate around the axis of the curve itself? Or is there perhaps an other way to make the particles move fluently along the curve?



Apparently Ctrl+T “twists” the selected control points.