Rheological properties, dispensing force and printing fidelity of starchy-gels modulated by concentration, temperature and resting time

Abstract

3D Food Printing (3DFP) is capable of creating a specific 3D food structure starting from a digital image. This capability can renew the way in which food manufacturing is thought. To this end, we modulated the properties of a starchy-gel system by systematically varying starch composition (the weight fraction of tapioca dextrin and cold water swelling waxy maize starch), the storage time before printing (ST), and printing temperature (PT). For each starchy-gel we have analyzed its rheological properties, printing behavior and the quality of the 3D printed replica and its microstructure. Analysis of the viscosity profile allowed determining the minimum stress (6.5 × 102 mPa s) at which the gels start to flow and are extruded from the syringe. We also determined the dispensing force needed to extrude the gels from the syringe, which at the extrusion rate of 26.4 mm3/s, showed a maximum value of 645.7 N at which the printing completely failed. Between these limits, a wide range of printing fidelities of gels was identified, where the printability was affected not only by the weight fraction of starch and printing temperature but also, and with high extent, by the time before printing. For instance, viscosity increased from 5 × 105 mPa s and 1 × 106 mPa s in the first 24 h of resting. Discrepancy from the 3D digital model regards not only the visual (external) aspect but also the microstructure features. The results of our research allow us to control the printability of starchy-gels and to create innovative food structures in which the local porosity/structure can be controlled based on the digital design.