Brown seaweed-derived cellulose for sustainable packaging: A review on extraction techniques, functional enhancement,...

Brown seaweeds are an abundant source of cellulose with promising potential for sustainable materials. This review synthesizes current knowledge on the occurrence, structure, and compositional features of cellulose within brown seaweed cell walls, and its association with alginates, fucoidans, and phenolic components. Among extraction methods, alkali treatment remains the most established, whereas enzymatic, ultrasonication, and microwave-assisted processes offer higher selectivity, shorter processing times, and reduced chemical inputs, particularly when used in hybrid sequences. Reported modification strategies, including surface oxidation/esterification, chemical-physical cross-linking, and composite formation with polysaccharides or proteins, consistently enhance tensile strength, water-vapour barrier performance, and thermal stability of cellulose-based materials. In food packaging, brown seaweed-derived cellulose is mainly employed as a reinforcing phase or structural matrix in films, where it improves mechanical integrity and enables active functions when combined with antimicrobial or antioxidant agents. The review identifies key gaps in process scale-up, standardization of quality metrics, and life-cycle assessment, and outlines research priorities to advance brown seaweed cellulose as a competitive component in sustainable packaging systems.