Influence of rheological characteristics on the quality of 3D printing of food pastes

In extrusion 3D printing, the rheological properties of food are critical to achieving quality printing. The aim of this study is to investigate potential correlations between the printability of food pastes and rheological characteristics. Potato and tomato puree were used as a model system. The rheological properties of mashed potatoes with the addition of potato starch and their behavior during 3D printing have been investigated. A correlation has been established between the formulation and manufacturability in 3D printing. Potato mass without starch had a low yield point, which affected the deformation and subsidence of the mass later. At the same time, the addition of 2% starch showed excellent extrudability and printability, that is, the ability to flow. Under these conditions, the printed objects had a smooth shape, good resolution, and could withstand shape over time. The object with the addition of 4% starch represented good shape retention but poor extrudability due to its high consistency index and toughness. The results obtained using tomato puree showed a linear correlation between ingredient flow stress, zero shear viscosity and corresponding print stability. The extrusion pressure required to extrude tomato paste increases linearly with increasing flow voltage. Modules of viscosity, elasticity, and zero shear rate turned out to be not linearly correlated with the extrusion force, which can be explained by the fact that these parameters reflect the rheological properties of the non-deforming state of the material, in contrast to the flow stresses.