Printability improvement of rice starch gel via catechin and procyanidin in hot extrusion 3D printing

Abstract In this study, catechin (CC) and procyanidin (PC) were introduced into rice starch gels to improve the printability of starch-based materials in hot-extrusion 3D printing (HE-3DP). Our results revealed that the composite starch gels had higher relative crystalline, compactness and inhomogeneity as the polyphenol concentration increased, outperforming the rice starch gel. The rheological results further indicated an enhanced printability based on the improved extrudability and structural recovery. The mass fractal dimension (Dm), correlation length (Ξ) and relative crystallinity (RC) were positively correlated with extrudability (G′2). In addition, 5–10% CC and 7.5–10% PC showed better printing performance, which indicated the proper values of Dm (1.63–1.73), Ξ (3.29–3.63), RC (5.77–8.99%) and G′2 (119.43–212.40 Pa) in the rice starch-based food of HE-3DP. In short, the relationship between printability and starch gel structure or rheological properties was clearly indicated. These findings would provide valuable guidance for selecting materials to optimize printing performance.