Construction of chitosan-sodium alginate core-shell microcapsules and their dual-functional application in tobacco mildew prevention and flavor preservation

Abstract

ABSTRACT Mold contamination and aroma depletion remain critical challenges during tobacco storage. Conventional chemical antifungal agents present residue risks, whereas the direct application of free fragrances is heavily constrained by their rapid volatilization. Herein, we engineered dual-functional core-shell microcapsules via a secondary cross-linking coupled with a vacuum freeze-drying process, encapsulating highly volatile vanillin and citral within a biodegradable chitosan-sodium alginate polyelectrolyte shell. Formulation optimization via an orthogonal array design (L9(34)) identified the optimal parameters as 1.2% chitosan with a 1:2 core-to-wall ratio. Under these conditions, the vanillin and citral microcapsules exhibited high encapsulation efficiencies of 14.23 ± 0.85% and 13.58 ± 0.79%, respectively, alongside highly suppressed 75-day cumulative release rates of 33.8% and 24.8%, respectively. Notably, the citral-loaded microcapsules demonstrated exceptional antifungal efficacy, achieving complete (100.0%) and 96.6 ± 1.1% inhibition against Aspergillus flavus and Aspergillus niger, respectively. Furthermore, during a 28-day accelerated tobacco aging trial, the microcapsule treatment reduced mold proliferation by over two orders of magnitude (>99.8%) and retained >65.0% of key aroma components, substantially enhancing the sensory quality. This study proposes an innovative “distal-proximal” synergistic strategy, providing an efficient, eco-friendly platform for simultaneous microbial control and aroma retention in active preservation materials.