Hi,
Have you considered Turbo slicer from the asset store, it has everything it seems:
http://noblemuffins.com/ From a gesture recognytion point of view, I would go with an existing pacakge such as Input.touches:
https://hutonggames.fogbugz.com/default.asp?W961-- but here nothing prevents you to roll your own solution totally in playmaker
For splitting the meshes, if you do it manually, you will likely provide the whole fruit, and the sliced fruit right? then it's only a matter of swaping objects and have some random anim going on top, it may sound simply, but I bet it has some pitfalls ( like slicing again a smaller chunck, how to animate realistically sliced portions, etc etc)
bye,
Jean