Dual-Functional Hydrogel for Iodine Uptake and Food-Grade Coating: Seed Waste Valorization

A natural hydrogel developed from the extract of Dillenia indica (elephant apple) seed waste facilitates iodine adsorption in polar and nonpolar solvents. This hydrogel also serves as a surface coating to enhance the shelf life of okra (Abelmoschus esculentus). The process involves the gel’s ability to capture iodine and demonstrates the antibacterial potential of the iodine-loaded gel. The gel was assessed for its effectiveness as a food-grade coating. The adsorption capacity in an aqueous system was measured at 48.40 mg/g, with a removal efficiency of 91.3% achieved within 120 min. In a hexane solution with the same initial iodine concentration, equilibrium was reached in approximately 240 min, showing an adsorption capacity of 21.8 mg/g and a removal efficiency of 89.9%. The impact of the coating on okra samples was evaluated by monitoring the weight loss and total phenolic content (TPC) and conducting a radical scanning assay (DPPH). The results indicated that the iodine-coated okra samples maintained their freshness for up to 8 days. This study highlights the potential of a hydrogel derived from natural seed waste for iodine adsorption and its importance as a biobased coating.