4D Printing of Sago Starch with Turmeric Blends: A Study on pH-Triggered Spontaneous Color Transformation

In recent years, the demand for customized products is on the rise, and 3D printing is emerging as a disruptive technology with the potential to revolutionize food manufacturing processes. Among the various facets of 4D printing, the color transformation of 3D-printed constructs in response to external stimuli is a field of growing research interest, particularly because the color of a food product is a key attribute that decides consumer preferences. In this study, turmeric powder was incorporated into sago flour at various levels (0, 0.5, 1.5, 2.5% w/w) and used as the 3D printing material supply. They were extrusion-printed in the in-house-developed food printer CARK (optimized at a printing speed of 2000 mm/min, with the pressure of 3 bar and nozzle diameter of 0.84 mm) and then immersed in solutions with varying concentrations of sodium bicarbonate (1, 3, and 5% w/w). The concentration and time-dependent shift in color from yellow to orange-red of the 3D constructs were evaluated, and the conditions were optimized considering sensory scores. This study provides insights into the development of a novel range of curcumin-based 4D-printed foods with color transformation capabilities.