Rheology of paste-like food inks for 3D printing: Effects of nutrient and water content.

This research delves into understanding the effects of composition on the rheological response of multi-component food inks for 3D food printing. Accordingly, the motivation is to decouple the nutrient and water content effects on the rheology. We formulated inks by combining pea fractions with water and employing a water-holding-capacity based hydration method. Rheology is characterized by steady shear rate and oscillatory strain amplitude sweeps. Strain sweep curves infer that the deformation response of all inks follows a similar trend, and samples sharing the same macronutrient formulation are mapped to a master curve after scaling with the elastic plateau modulus. Samples sharing the same macronutrient formulation mapped to a master curve after scaling with the elastic modulus. Shear rate testing showed that the inks were shear thinning yield stress materials. Shear rate sweeps also collapsed on a master curve scaled by the yield stress and critical shear rate on the y and x axes. The yield stress and the plateau modulus appeared to be controlled by the water content, while the shear and strain thinning exponents were independent of the formulations, inferring that the rheology is scaled by the water content while preserving the shear thinning response. Observing the independence of the rheological properties from the nutrient composition and scalability of the rheology by the water content provided a step forward in developing formulations with various nutrient content at desired ow properties, which promises personalized nutrition. Furthermore, the study shows the applicability of various rheological techniques, which are expected to contribute to the literature on the rheology of granular pastes.