3D printing confectionaries with tunable mechanical properties

This paper reports 3D printing of confectionaries using the binder jetting method, where an aqueous binder was printed to selectively join the sugar particles together. Two orders of magnitude difference in compressive strength (from 23 kPa to 1551 kPa) and one order of magnitude difference in elastic modulus (from 1151 kPa to 16,838 kPa) were achieved by adjusting the glycerol concentration of the binder. Such high degree of tunability was attributed to the primary type of bridging (solid versus liquid) between the bound sugar particles. The compressive strength of the 3D printed samples varied between those of a filled hard candy and a marshmallow, although the elastic modulus was at least one order of magnitude higher. Further, a "soft core and hard shell" design was printed and modeled. The discrepancies between experimental and simulation results may be explained by glycerol leaching caused by a glycerol concentration gradient and/or capillary actions.