Emulsion-loading-driven transitions in microstructure and release kinetics of sodium alginate films incorporating a succinylated pea protein-stabilized cinnamon essential oil Pickering emulsion.

Abstract

In this study, cinnamon essential oil (CEO) Pickering emulsions stabilized by succinylated pea protein isolate (SPPI) were incorporated into sodium alginate (SA)-based films to demonstrate that appropriate formulation is critical for achieving sustained CEO release, antioxidant and antimicrobial functionality, and effective preservation of fresh produce while maintaining desirable mechanical and barrier properties. Films containing different emulsion loadings were prepared, and their microstructural features, mechanical, optical, and moisture barrier properties, CEO release behavior, antioxidant and antimicrobial activities, and preservation performance for cherry tomatoes were systematically evaluated. Multiple kinetic models (first-order, Ritger-Peppas, Peppas-Sahlin, Peleg, and Weibull) were applied to analyze the release behavior, enabling quantification of the initial burst release, release constants, and correlation coefficients. These parameters were interpreted in relation to the film microstructure. The results revealed that an intermediate emulsion content effectively suppressed the initial burst release, ensured adequate cumulative CEO release, and preserved a balance between mechanical integrity and moisture barrier performance, resulting in consistent preservation efficacy in practical cherry tomato storage tests. In contrast, films with high emulsion contents exhibited greater absolute CEO release and enhanced antioxidant and antibacterial activities, but failed to provide further improvements in preservation performance due to excessive initial release and compromised mechanical robustness. These findings highlight the inherent trade-offs among release behavior, functionality, and structural stability, underscoring the importance of formulation optimization for specific application environments. This study provides quantitative and empirical guidance for such optimization by integrating experimental outcomes with kinetic indices.