Rheology, Printability, and Texture of Extrusion-Based 3D-Printed Self-Supporting Soft Gels Formulated with Pea and Chickpea Proteins

Predicting printability and final texture in extrusion-based 3D printing of soft, self-supporting food gels remains challenging, particularly when realistic plant-based ingredients are used instead of simplified model systems. In this study, two plant protein–hydrocolloid inks based on commercial pea protein isolate (PPI) and chickpea protein concentrate (CPC) were developed and compared within the same hydrocolloid framework (0.36% low-acyl gellan gum and 1.00% xanthan gum). The formulations differed in protein ingredient level, moisture content, sorbitol concentration, and salt origin, allowing evaluation of how complete formulation design governs rheology, printability, and texture. The CPC-based ink showed higher yield stress than the PPI-based ink (158.10 ± 18.17 vs. 119.56 ± 18.84 Pa), whereas both inks exhibited similar shear-thinning behavior (n ≈ 0.35). Thixotropic recovery at 60 °C was limited in both systems (16–19%), while oscillatory tests revealed weak-gel behavior, with higher Bohlin gel strength for the PPI-based ink (65.69 ± 5.59 vs. 38.97 ± 2.08 kPa). Both formulations enabled continuous extrusion and the fabrication of self-supporting printed objects, although geometric fidelity of the internal infill remained limited, particularly in CPC samples. Compression testing showed that CPC gels were slightly stiffer and tougher, whereas PPI gels were more resistant to irreversible deformation. Overall, the results indicate that when commercial ingredients are used for food 3D printing purposes, rheology, printability, and final texture were governed primarily by the formulation design, rather than by protein source alone.