Resolving molecular-level interactions of starch and fatty acids with distinct structures by multidimensional solid-state NMR approaches.
This study explored interaction mechanisms between mono-, di-, and triacylglycerols (GMO, GDO, and GTO) and high-amylose corn starch (HACS) at atomic resolution using multiple techniques, including Fourier transform infrared spectroscopy, X-ray diffraction, and solid-state NMR, such as 1H spin-lattice relaxation time (T1) and heteronuclear correlation (HETCOR) to analyze molecular mobility and binding sites. Results showed that GMO and GDO exhibited superior complexation ability with starch compared to GTO and successfully induced the formation of V-type structure. HACS-GMO (2.35 s) and HACS-GDO complexes (2.22 s) showed similar T1 relaxation times, which were different from HACS-GTO (2.01 s) and starch (1.92 s), indicating distinct interaction modes. Furthermore, 1H-13C HETCOR indicated the HACS-GDO complex exhibited the strongest cross-peaks, suggesting stronger intermolecular interactions. The C-2,3,5 of starch may be involved as binding sites for the formation of inclusion complexes with GMO and GDO, whereas the interaction between GTO and starch is relatively weak.