Printing stability is linearly related to flow stress and zero shear viscosity.
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Extrusion pressure is proportional to flow stress for aqueous food formulations.
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Fat-based products require higher extrusion force due to strain hardening.
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Rational guideline is proposed for recipe and printing design development.
Abstract
Development of 3D food printing applications requires in-depth knowledge on printing behaviour of food materials. In extrusion-based 3D printing, rheological properties of a recipe are critical to achieve successful printing. The objective of this research is to investigate potential correlations between printability of formulations and simple rheological properties. We used tomato paste as a model system to investigate the correlation between printing stability, dispensability and rheological properties. The results show a linear correlation between ingredient's flow stress, zero shear viscosity and corresponding printing stability. The extrusion pressure necessary to extrude tomato paste increased linearly with increasing flow stress. More experiments with other aqueous-based food formulations indicated that their printability aligned reasonably well with the correlation of tomato paste; however, for fat-based products different printing behaviour was observed. Finally, we propose a rational guideline for developing aqueous food recipes with desired printability based on flow stress measured by shear rheology.
