Sinusoidal voltage pulsed electrolysis induced anthocyanins discoloration: an improved method for colorful food 3D...

Electrolysis-assisted 3D printing enables on-demand color tuning of starch-anthocyanin gels via in situ pH modulation. However, direct-current (DC) driving promotes vigorous gas evolution that broadens filaments, roughens surfaces, and compromises color uniformity. Here, we introduce waveform-engineered pulsed electrolysis and compare rectangular, triangular, and sinusoidal pulses (250-1000 Hz) at matched effective voltage. Across frequencies, pulsed operation reduced line expansion and increased stack height relative to DC. Sinusoidal pulsing delivered the smallest linear expansion and the most stable stacking, approaching the 30 mm design height. At 60 V, sinusoidal excitation produced the lowest color deviation (ΔE = 1.36 ± 0.21) and improved water retention and texture compared with the other waveforms. Finite element analysis (FEA) showed that the strongest pH gradient is localized at the nozzle exit, consistent with immediate coloration of the extruded filament. Simulated and experimental discoloration ranges agreed within ∼11%. Overall, sinusoidal pulsing around 1 kHz provides a practical route to suppress bubble-induced defects and enable high-fidelity, color-stable electrochemical food printing.