Effect of amylose content and crystal type on the structure and digestibility of starch-fatty acid complex nanoparticle

To understand how amylose content and crystal type regulated the digestibility of starch–lipid complex nanoparticles, this study used waxy corn starch (WCS), normal corn starch (NCS) and high-amylose corn starch (HCS) with different amylose contents and NCS (A-type), potato starch (PtS, B-type) and pea starch (PS, C-type) with different crystal types to investigate the effects of amylose content and crystal type on the structure and digestibility of starch-lauric acid (LA) complex nanoparticles. A significant increase in complex index (CI), R1047/1022, relative crystallinity, and enthalpy of gelatinization (ΔH) was found in starch-LA complex nanoparticles with amylose contents increasing. The increases in resistant starch (RS) and slowly digestible starch (SDS) contents of WCS-LA complex nanoparticles, NCS-LA complex nanoparticles and HCS-LA complex nanoparticles were 29.33%, 40.29% and 93.90% compared to their respective controls. Furthermore, PtS-LA complex nanoparticles (PtS-LANPs) showed the highest increase in CI, R1047/1022, relative crystallinity, and ΔH compared to NCS-LA complex nanoparticles (NCS–LANPs) and PS-LA complex nanoparticles (PS-LANPs). For RS and SDS contents, the highest increased was found in PtS-LANPs (56.99%), followed by NCS–LANPs (40.29%) and PS-LANPs (31.44%) as compared to their respective controls. Results could provide basic data to prepare starch–lipid complex nanoparticles with desired digestibility. •HCS-LANPs exhibited the higher RS & SDS contents compared to WCS-LANPs and NCS-LANPs.•PtS-LANPs presented the higher RS & SDS contents compared to NCS-LANPs and PS-LANPs.•HCS-LANPs and PtS-LANPs showed high short-range, long-range and double helical order.•HCS and PtS showed greater complexation effect and intermolecular interaction with LA.•Amylose content and crystal type affected starch-LA complex nanoparticle’ digestibility.