Pomegranate Leaf Extract as a Source of Bioactive Compounds for Edible Coatings Applied to Strawberry Postharvest Preservation

This study investigated the use of aqueous pomegranate (Punica granatum L.) leaf extracts as a source of bioactive compounds in edible coatings for strawberry postharvest preservation. Extraction conditions were evaluated by varying solid-to-solvent ratio, temperature, and time, using total phenolic content (TPC) as the response variable. Response surface analysis indicated that the best predicted extraction conditions within the studied range were 1:50 (w/v), 57.36 °C, and 25 min. Among the evaluated treatments, extract C503 (1:50 (w/v), 50 °C, and 25 min) showed the highest experimental TPC (474.62 ± 21.69 mg GAE/g DM) and was selected for further characterization. This extract also showed high antioxidant capacity (FRAP: 7085 ± 72.0 µM FeSO4/g; ABTS: 4921 ± 149.0 µM Trolox/g) and antimicrobial activity against Listeria monocytogenes and Staphylococcus aureus. When incorporated into gelatin- and starch-based edible coatings and applied to strawberries, both coatings reduced mass loss and delayed deterioration during nine days of storage at room temperature. At the end of storage, mass loss was reduced by approximately 25% with the gelatin-based coating and 11% with the starch-based coating. These results support aqueous pomegranate leaf extract as a promising source of bioactive compounds for the development of sustainable edible coatings to improve strawberry preservation.