Regulation of Starch-Lauric Acid Complex Properties by Amylose Molecular Weight: Structure, Digestibility, and Gut Microbiota Fermentation.

The molecular weight (MW) of amylose is a critical determinant of the structure and functionality of amylose-lipid complexes (RS5). This study investigated complexes constructed from high-MW (HCK) and low-MW (CGK) amylose with lauric acid by using an in vitro digestion-fermentation model. A distinct paradox emerged: while CGK-based complexes exhibited a higher initial resistant starch content (46.09%), the digested HCK residue retained a more robust crystalline architecture. Mechanistically, this structural preservation rendered digested HCK a superior prebiotic substrate, significantly promoting beneficial taxa (e.g., Bifidobacterium and Prevotella) and suppressing pathogens (Proteobacteria) compared to the low-MW counterpart. These findings demonstrate that amylose MW is a pivotal parameter for engineering RS5: low-MW amylose maximizes the RS yield for glycemic management, whereas high-MW amylose constructs robust complexes for targeted gut microbiota modulation.