Effect of grapefruit peel pectin on the structure, pasting characteristics, and in vitro digestibility of starch...

This study aims to explore the effects of hydrothermal treatment (HT)-assisted grapefruit peel pectin on the physicochemical, morphological, thermal, and pasting characteristics and in vitro digestibility of corn starch under varying temperatures and moisture content. Morphological analysis revealed that pectin uniformly coated starch granules, forming protective layers and rearranging crystalline structures. Fourier transform infrared spectroscopy and ¹³C nuclear magnetic resonance confirmed alterations in molecular order, with increases in single-helix structures and reductions in double-helix structures. X-ray diffraction and differential scanning calorimetry highlighted significant reductions in crystallinity and changes in thermal properties, indicating compact structural arrangements. Pasting and in vitro digestibility results revealed HT-C/P@60/80 exhibiting the highest resistant starch content and the lowest rapidly digestible starch content. Molecular docking and dynamics simulations demonstrated that pectin binds to α-amylase, then potentially inhibiting its catalytic activity. These findings highlight the role of pectin in altering starch properties for better food applications.