Melanin from Pecan Nut Shell Waste as an Antioxidant and Antifungal Additive in Membranes for Food Packaging

Abstract

The increasing global demand for sustainable and effective food preservation methods has prompted the development of novel technology. The utilization of biomass generates valuable compounds that can be applied in innovative technologies like next-generation packaging, thereby enhancing environmental quality through the recycling of materials previously considered as waste. In this study, melanin was isolated from Pecan nut shells (Carya illinoensis Koch), with an optimized extraction process that enables the extraction of around 88 g of melanin per kilogram of Pecan shells. Melanin was electrospun with concentrations of 1.0 and 3.0 wt% using a hybrid mixture of polycaprolactone (PCL) and gelatin (Gel). Polycaprolactone-gelatin (PG)/melanin membranes showed an antioxidant capacity associated with efficient behavior as a hydrogen atom donor. The presence of -OH functional groups and catecholic compounds in melanin allows interaction with water molecules, enabling the transition from highly hydrophobic to hydrophilic behavior. Additionally, fibers showed antifungal activity against three phytopathogenic fungal strains isolated from commercial strawberries (Fragaria x ananassa L.) due to the release of H₂O₂ from the oxidation of catechols. All these active properties are intended to be used in food packaging.