Ultralow concentrations of curcumin as a structural modifier in chitosan coatings for eco-friendly postharvest preservation of strawberries

This study evaluated the impact of low concentrations of curcumin (2.5-20 µM) on chitosan edible coatings for strawberry preservation. Films obtained by solvent casting were characterized by ATR-FTIR spectroscopy, thickness, moisture content, water vapor permeability, water solubility, and soil degradability. The results indicate that curcumin reduces moisture, solubility, and biodegradability, suggesting the formation of a more cohesive matrix. Furthermore, the spectroscopy results demonstrated that curcumin interacts with chitosan chains through hydrogen bonds without cross-linking. To test the protective effects, strawberries were coated and stored at 20 °C for 7 days. Data on weight loss, visual decay, firmness, soluble solids content, and color change (ΔE) confirmed that chitosan-curcumin (CS-Cur) formulations were superior to uncoated and neat chitosan controls. Considering that even at low concentrations, curcumin acts as a structural modifier and bioactive agent, CS-Cur coatings have potential as an ecological package for fresh fruit. Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1007/s10068-026-02245-2.