Interactions in starch-lipid complex systems improve 3D printing accuracy and form resistant starch structures: Based on complex properties and molecular simulations.

This study investigated the 3D printability, structural properties, and digestibility of starch-lipid complexes using physicochemical analyses combined with molecular dynamics simulations. Lipid saturation and esterification significantly affected the rheology, thermal stability, and water mobility of wheat starch gels, thus influencing there printing performance. Incorporating linoleic acid (LA) or glycerol trioleate (GT) enhanced shear-thinning behavior and printing precision by forming looser complexes caused by steric hindrance. These structures changes improved hardness and adhesiveness, facilitating high-precision printing suitable for dysphagia-friendly foods. Although the reduction in V-type crystallinity suggests fewer highly ordered starch-lipid complexes and more amorphous regions, these amorphous domains, together with the structural adaptability provided by highly unsaturated and esterified lipids, promoted the formation of interconnected porous networks, thereby reinforcing the structural integrity of the 3D-printed samples. In vitro digestion revealed that GT reduced starch hydrolysis by competitively binding to α-amylase. Molecular dynamics simulations revealed that the OA complex, with lower total energy, exhibited more stable binding and stronger enzyme affinity, leading to higher susceptibility to hydrolysis and increased digestibility. Conversely, the GT complex showed reduced structural stability and order, aligning with its lower digestion rate. These findings provide a solid theoretical basis for incorporating glycerol trioleate into starch to develop slowly digestible, swallowable foods.