Multiscale structure change regulates the functional properties of proso millet starch-oleic acid-ferulic acid ternary system during hot extrusion three-dimensional printing.

This study investigates the effects of introducing oleic acid and/or ferulic acid into a proso millet starch system on starch retrogradation, starch digestion, and lipid oxidation stability via hot-extrusion three-dimensional printing. To elucidate its regulatory mechanism from a structural perspective, the multiscale structures of complex are characterized and supplemented with textural, digestive, and oxidative stability analyses. The introduction of oleic acids and/or ferulic acids induce the formation of V-type and non-V-type inclusions, accompanied by an increase in relative crystallinity (reaching 21.21 % at day 7) and helical structure content (reaching 33.44 % at day 7). The generation of such ordered structures enhances the resistance of complexes to digestive enzymes and exerts spatial blocking effects that hinder the stacking of locally ordered structures and lipid oxidation. Therefore, ternary complexes demonstrate a lower retrogradation degree (reaching 28.07 at day 7), starch digestibility (reaching 80.14 % at day 7), and total oxidation value (peaking at 13.90).