Cinnamon essential oil-loaded SA/PVA hydrogel beads: Sustained release and effects on strawberry quality during storage at 4 ℃

Emulsion/hydrogel bead systems offer a potential strategy to improve the handling and release control of volatile plant essential oils. In this study, cinnamon essential oil-loaded sodium alginate/polyvinyl alcohol hydrogel beads (SA/PVA–CEO) were prepared by ionic crosslinking and evaluated as a proof-of-concept non-contact preservation system for strawberries stored at 4 °C. The optimal formulation exhibited high apparent encapsulation efficiency, spherical bead morphology, and a compact structure in the dried state. FTIR spectral changes suggested possible interactions between CEO and the SA/PVA matrix, while TG–DSC analysis indicated improved thermal resistance of CEO after incorporation into the hydrogel beads. The beads exhibited a diffusion-related release behavior in food-simulating media at 4 °C over 12 d. In preliminary CCK-8 assay using AML-12 cells, CEO emulsion and blank SA/PVA hydrogel bead extract showed lower apparent cytotoxicity than free CEO under the tested concentration range. In the refrigerated strawberry storage trial, each treatment contained 12 fruits arranged in three biological replicates. The 1:1 CEO emulsion-to-PVA/SA formulation showed the best overall quality retention, with lower visible decay, reduced weight loss, higher firmness, and better maintenance of total soluble solids and titratable acidity than the control after 12 d. This treatment was also associated with lower MDA accumulation and changes in antioxidant- and browning-related enzyme activities. These results suggest that SA/PVA–CEO hydrogel beads may help delay strawberry quality deterioration under laboratory refrigerated storage conditions. Further studies on CEO chemical profiling, migration behavior, microbial control, sensory effects, packaging compatibility, and scale-up validation are required before practical application.