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

Abstract 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.