A Novel Gellan Gum-Chitosan Composite Film Functionalized with Melatonin for Enhanced Preservation of Fresh Blueberries

The demand for sustainable food packaging is increasing. This study developed a novel ternary composite film based on gellan gum (GG), chitosan (CS), and melatonin (MT) for preserving fresh blueberries. For the first time, MT was incorporated as a functional agent into a GG/CS matrix. Films with varying compositions were prepared and characterized. The GG-dominant film with the highest MT content (G2C-M50, 2:1:0.5 <i>w</i>/<i>w</i>) exhibited optimal properties, including high tensile strength, enhanced flexibility, and a superior moisture barrier. In a 7-day storage trial, this film dramatically extended blueberry shelf-life, reducing the spoilage rate to 2.2% while maintaining 80.5% of the initial anthocyanin content. This success is attributed to the synergy between the robust GG/CS physical network and the multifunctional (antioxidant, antimicrobial) activities of MT. This work presents a highly effective strategy for active food packaging.