Characterization and mechanism of ferulic acid/γ-cyclodextrin inclusion complex: Stoichiometric optimization and...

Ferulic acid (FA) exhibits strong bioactivity but is limited by poor aqueous solubility and photostability. To address these limitations, this study evaluated the physicochemical properties of FA/γ-cyclodextrin (γ-CD) inclusion complexes prepared at varying molar ratios (1:1, 1:2, and 2:1). Structural characterizations confirmed successful encapsulation through crystalline phase transformations and morphological changes. Among the tested formulations, the 1:2 complex achieved the highest encapsulation efficiency (79.74%), while the 2:1 complex maximized loading efficiency (20.45%) and solubility (5.9-fold enhancement). The 1:1 complex exhibited enhanced photoprotection during the early stage of storage (92.3% retention over 4 days) and the highest in vitro intestinal bioaccessibility (86%). To further understand the underlying mechanism, molecular dynamics simulations were conducted, revealing that the stability of the 1:1 complex is mainly driven by van der Waals interactions, with additional contributions from hydrogen bonding. Furthermore, active packaging films were developed by incorporating the 1:1 complex (6 mg) into a hydroxypropyl methylcellulose matrix, and they showed good UV-blocking performance and mechanical properties. Application in fresh-cut apples revealed that the films effectively reduced enzymatic browning and maintained firmness during a 5-day storage period. This study offers new insights into molar ratio-dependent CD complexation and provides guidance for the design of active food packaging systems.