Textural modification of 3D printed dark chocolate by varying internal infill structure.

This study aimed to create an intricate internal structure of 3D printed chocolate by varying the infill construction. Three intricate infill patterns designed were star, Hilbert curve and honeycomb with infill percentage of 5%, 30%, 60% and 100%. Cadbury dark chocolate (Choc-1) and Callebaut bittersweet dark chocolate (Choc-2) powders were used by incorporating magnesium stearate (Mg-ST) and plant sterol (PS) powders as food additives. Printing parameters were set up with an extrusion temperature of 32 °C, nozzle size of 0.78 mm and printing speed of 70 mm/s. The results showed that voids in printed samples of all three pattern with 5% infill density ranged from 60.8 ± 2.1% to 72.2 ± 1.8%. Voids in samples with 30% infill density ranged from 20.9 ± 2.1% to 49.2 ± 3.6% while with 60% infill density it ranged from 11.6 ± 2.3% to 19.4 ± 4.2%. Additionally, star and honeycomb infill pattern produced the most stable and tough structure at 60% infill as indicated by a higher normal force (N) to break the printed sample. Moreover, even at 100% infill percentage, 3D printed chocolate were found less hard (ranged from 82.2 ± 2.2 N to 92.2 ± 1.3 N) as compared to cast samples (>110 N) in the snap test. The results obtained in this study provide a useful insight in creating various internal structures of 3D printed dark chocolate with different textural characteristic and physical stability.