Complexation mechanism of high-amylose corn starch and myristic acid in CaCl2 aqueous solution: The role of Ca2+ coordination structure

Starch-lipid complexes have potential applications in functional foods, food additives, and food packaging materials. High-amylose corn starch (HACS) is a promising raw material for starch-lipid complexation. To overcome the poor gelatinization of HACS under atmospheric pressure, we leveraged the capacity of a CaCl₂ aqueous solution to dissolve HACS, thereby streamlining the preparation of HACS-lipid complexes. Taking myristic acid (MA) as example, the HACS-MA (H-MA) complex prepared in deionized water exhibited a complexing index (CI) of 36.15 %, whereas that prepared in CaCl₂ aqueous solution achieved a significantly higher CI of 89.03 %. Chemical group analysis and thermal characterization indicated that Ca²⁺ ions not only enhanced HACS dissolution through metal-dipole interactions but also bound to the hydroxyl oxygen atoms of starch, forming a coordination structure that promoted a single helical arrangement. This study clarifies the mechanism of starch-lipid complexation in CaCl₂ aqueous solution and defines the role of Ca²⁺ ions in the complexes.