Theoretical and experimental investigation of sodium alginate composite films containing star anise ethanol extract/hydroxypropyl‐β‐cyclodextrin inclusion complex

Abstract The aim of this study is to prepare composite films incorporated with star anise ethanol extract (SAEE)/hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) inclusion complex. The effects of sodium alginate concentration on mechanical properties of films are tested. Sodium alginate, SAEE, and SAEE/HP‐β‐CD inclusion complex‐based composite films are characterized in terms of UV‐visible spectroscopy, microstructure characterizations, including transmission electron microscopy, scanning electronic microscopy, Fourier transform infrared, and 1 H NMR analysis, and molecular modeling calculations. With various stoichiometries, the complexes of sodium alginate/SAEE/HP‐β‐CD are compared through both theoretical and experimental analyses. Molecular simulations are applied to predict the possible orientations of SAEE inside the HP‐β‐CD cavity and the optimal stoichiometry of the complex formation. According to the simulation, the system of sodium alginate/SAEE (or SAEE/HP‐β‐CD inclusion complex) in a 3:1 stoichiometry reaches the lowest total energy and achieves a balance in complex system. In addition, the composite films can maintain high‐content vitamin C and reduce weight loss rate of fresh‐cut Chinese yam. In conclusion, coinciding with the experimental results, the molecular modeling successfully calculates the reasonable molecular structure and molecular behavior of sodium alginate/SAEE/HP‐β‐CD inclusion complex. The composite films in this study have the potential to be used for food packaging applications. Practical Application In this paper, we present composite films incorporated with star anise ethanol extract (SAEE)/hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) inclusion complex for the use of fresh‐cut Chinese yam preservation. The present study demonstrates a successful application of molecular modeling to predict the geometry of the final complex. It can serve as a powerful tool to calculate the energy of association between inclusion complex and sodium alginate molecules.