Comparing the rheological and 3D printing behavior of pea and soy protein isolate pastes

In this study the viscoelastic properties of pea and soy protein pastes with concentrations ranging from 10 to 21%w/w were correlated with their 'printability' following extrusion 3D printing. The rheological parameters G´, tanδ and σy were affected by the protein concentration, and a different viscoelastic behavior was observed for PPI and SPI pastes. At low protein concentrations (10–16%w/w) SPI presents a more elastic behavior than PPI, whereas at higher protein concentrations (>17%w/w) their rheological behavior was similar. No self-supporting structures could be printed for pastes with protein concentrations <15%w/w. In the protein range of 15–17%w/w, SPI formed more stable 3D printed objects compared to PPI. SPI shows a more elastic structure that increases stability against collapse during 3D printing. At higher protein concentrations for PPI, the increase of G´, σy and K counteracted the importance of n and tanδ, resulting in self-supporting 3D printed products comparable to SPI. This work provides a better understanding of the importance of rheology of plant-protein food inks to printability by attempting to establish printing predictors, which is important for the development of new inks for 3D printed foods.