NMR investigations of plant biopolymers, from the molecule to the supramolecular organisation. Various NMR techniques have been used to characterize plant biopolymers, isolated or in interaction with other macromolecules in complex composites. In our investigations, 1H and 13C NMR spectroscopy is used to study, at the molecular scale, complex biochemical processes as those involved during fruit ripening. NMR informs also about the fine structure of biopolymers, about their polymorphism and their crystallinity. At supramolecular scales, measurements of self-diffusion coefficients complement the low-field relaxometry approaches in order to estimate pore sizes in composite systems of biopolymers.