Development and characterization of bioactive Dictyophora rubrovalvata polysaccharide/hydroxypropyl starch composite films loaded with eugenol for strawberry preservation.

In this study, Dictyophora rubrovalvata polysaccharide (DRP) was introduced into starch (CS) and hydroxypropyl starch (HPS) matrices to develop a composite film with enhanced physicochemical properties and investigate its potential for use in fruit preservation. Films based on CS, CS-DRP, HPS and HPS-DRP were prepared via solution casting method. The structural characteristics of the films were investigated using rheology, spectroscopy, and textural analyses, alongside systematic evaluation of their physical properties. Results showed that among all groups, the HPS-DRP film exhibited the best polymer compatibility, with its film-forming solution demonstrating an elastic-dominated rheological system and a smooth, uniform microstructure. Meanwhile, the hydrogen-bond interactions between DRP and HPS conferred superior mechanical properties, barrier performance and thermal stability to the film, achieving a tensile strength of 4.55 MPa, an elongation at break of 86.81%, a water vapor permeability of 5.63 × 10-10 g·m-1·s-1·Pa-1, and a residual rate of 21.87% after thermal degradation. Following the incorporation of eugenol, the HPS-DRP composite film exhibited good antimicrobial activity and effectively extended the shelf life when applied to strawberry preservation. These results demonstrate that HPS-DRP composite film holds broad application prospects as an active packaging material in fruit preservation.