Development and characterization of carrageenan-based antibacterial films incorporated with natural melanin pigment from niger seed hulls (Guizotia abyssinica) and their efficacy to enhance the shelf-life of strawberries

Abstract

Enhancing the safety and quality of minimally processed foods is a top priority for consumers and the food industry. There is an urgent need for eco-friendly and sustainable packaging films to protect fresh food products. In this study, we attempted to develop carrageenan-based films incorporated with melanin extract with enhanced physicochemical properties, antibacterial activity, and effectiveness in maintaining the quality of strawberries during storage. The carrageenan-melanin films were produced using a solution casting method, incorporating melanin extracted from niger seed hulls as a bioactive additive. The impact of melanin content on the structural, thermal, water barrier, antioxidant, and antimicrobial properties of the carrageenan-based films was assessed. FTIR analysis validated the successful integration of melanin into the carrageenan matrix. The antibacterial activity of the carrageenan-melanin (30 mg) films was tested against common foodborne pathogens, showing effectiveness against Salmonella enterica (60 mm), Staphylococcus aureus (40 mm), Micrococcus luteus (36.67 mm), Klebsiella oxytoca (40 mm), Escherichia coli (42 mm), and Bacillus cereus (31 mm), outperforming the chloramphenicol control. The carrageenan-melanin film (30 mg) significantly restricted bacterial counts and effectively extended the shelf life of strawberries stored at room temperature (25 °C ± 2) for five days and maintained lower heterotrophic bacterial count subsequently. Precise analysis of volatile organic compounds with a sophisticated electronic nose (E-nose) system, revealed the freshness profile of strawberries during storage. Overall, the carrageenan-melanin film shows great promise as a sustainable packaging material with enhanced antibacterial properties for preserving strawberries, representing an innovative solution for sustainable food packaging.