Color 3D printing of pulped yam utilizing a natural pH sensitive pigment

A novel color control strategy for 3D printing was proposed based on a single channel nozzle with a single raw material. The basic principle was to regulate the pH of the extruded line through electrolysis which would result in the color change of pH-sensitive pigments mixed in the printed materials. Using pulped yam as a feedstock and a pH sensitive pigment extracted from purple sweet potato (PPP), the process parameters were optimized using a moisture content of 35% and a PPP content of 5 mg/100 g. Printing tests showed that the color of the extruded line could be conveniently controlled by adjusting the applied electrode potential from − 45 to 45 V with a hue range of 0.192–0.916, which exhibited a gradually changing color scheme from mauve to yellow. The proposed strategy showed promising potential in color 3D printing with the advantages of low cost, convenient control and simple composition.