Structure-activity relationships of polyphenol-rice starch complexes: Impact on 3D printing and resistant starch formation

This study aimed to investigate the effects of gallic acid (GA), luteolin (LUT), and quercetin (QUE) on the structure, physicochemical characteristics, and 3D printing behavior of rice starch and to elucidate the underlying mechanisms. The results revealed that incorporating GA significantly decreased the viscoelasticity of rice starch, reducing the printing accuracy from 98.64 % to 72.4 %. However, the polyhydroxy structures of LUT and QUE helped maintain the network strength of the starch gel, exerting a minimal influence on the 3D printing performance. Structural and molecular docking analyses demonstrated that all three polyphenols bind to starch molecules via hydrogen bonding, forming single-helix complexes that disrupt the double-helix gel network, thereby lowering the gel viscoelasticity. Moreover, the addition of polyphenols significantly increased the resistant starch content in the 3D-printed products, from 22.10 % in natural starch to 53.36 % in the starch-GA complex, 47.79 % in the starch-LUT complex, and 48.34 % in the starch-QUE complex. These findings offer valuable insights for advancing the development of functional 3D-printed foods.