This study explores the rheology, functionality and extrusion-based 3D printability of pea protein concentrates derived from sustainable tribo-electrostatic separation (TES) of yellow peas, processed through two milling systems—pin and Ferkar—at varying intensities of Fine and Coarse. Composite mixtures were also formulated with wet-based-derived protein and starch isolates of yellow pea, and oat fiber to investigate component–rheological-functional properties relationships relevant to additive food manufacturing.
Rheological assessments—including steady-state flow sweep, dynamic stress and frequency sweeps, temperature sweep and shear recovery of viscosity—were used to characterize the viscoelasticity, shear-thinning behavior, and recovery capacity and thermal stability of printable pastes. Functional tests included oil and water absorption capacities (OAC and WAC, respectively), emulsion stability (ES), and foam stability (FS).
The inclusion of oat fiber enhanced shear-thinning properties, yield stress, and shear recovery along with increased WAC, OAC and FS— contributing to smooth extrudability and improved shape and thermal stability. While protein and fiber promoted similar effects on rheological and functional properties, starch required thermal pre-treatment to develop adequate binding interactions with other ingredients and water. The heating treatment at 65 ºC resulted in improved ES and complex viscosity, enabling smooth extrusion and precise 3D printing results with increased maximum number of layers developed after 3D printing.
In regard to the TES-derived protein concentrates, ES was more strongly influenced by milling type than intensity, with TES-derived protein concentrates from pin-milled yellow pea flours exhibiting the highest ES. Fine-intensity milling, regardless of milling type, improved OAC. Furthermore, fine pin milled protein concnetrates demonstrated the highest WAC and FS, suggesting that fine milling promotes greater interfacial activity and water-binding potential due to increased surface area and reduced particle size. The superior functional properties of the fine pin-milled protein concentrates were reflected in its enhanced rheological behaviors, including higher yield stress, shear recovery and shear-thinning behaviors, which contributed to improved print fidelity and maximum achievable height through 3D printing.
These findings demonstrate the potential of TES-separated pea protein concentrates—particularly fine pin-milled protein concentrates— as ingredients with high functional and mechanical properties for nutritionally enhanced 3D-printed foods. Moreover, the study highlights strong correlations between the key functional and rheological parameters and 3D printability, underscoring their critical role in optimizing and scaling the additive manufacturing technology.