Additive Manufacturing (AM) opens new perspectives for biopolymers in functional material applications, as for the production of biomedical devices, exploiting their biocompatibility and resorbability. Plasticized materials from zein, a storage protein from maize seed endosperm, could display thermomechanical properties matching with Fused Deposition Modeling (FDM). The objective of this work was to evaluate their thermo-rheological behaviour during processing, in relation with their structural modifications. For this purpose, 20% glycerol was added to commercial zein, containing naturally about 4% lipids and 5% water. After storage at intermediate relative humidity (RH=59%), its glass transition temperature, measured by DSC, was Tg=42°C. The principal mechanical relaxation, measured by DMA, was found at Tα=50°C, leading to a drop of the elastic modulus from E’=1.1GPa, at ambient temperature, to E’=0.6MPa at Tα+100°C. These values are in a similar range as those of standard polymers used for AM-FDM processing, such as PLA and ABS. The molecular structure of zein was characterized at different scales by SDS-PAGE, reversed-phase HPLC, FTIR and WAXS, at each processing stage: (i) the initial formulation of the plasticized powdery material, (ii) after extrusion at 130°C for shaping printable filaments, and (iii) after deposition through the 3D printer nozzle (Ønozzle=0.5mm, Tprinting=130°C, vprinting≈10mm/s). The presence of disulfide bond cross-links was evidenced in extruded filaments and remains at the same level after printing. It was checked by WAXS that, in these conditions, no molecular orientation was obtained in the deposited material. These results lead to the setting up of zein-based printable compositions, by shedding light on the structural changes of these materials during processing. This opens the field of their processing as resorbable printed parts, with a controlled geometry and a designed tridimensional structure.