Banana peels: the point is long fibre, the hardest test for a disposer, because it wraps instead of breaking. Only the top-range models get particles this fine: with the basic ones the residue stops earlier. The issue is the long fibres, not the texture: cut into short pieces and mixed with other leftovers, the peel does not wrap around inside the chamber. They're fibrous: cut them up and mix with other scraps. If you produce a lot of it, it is worth checking your water utility’s rules.