Plant and algal mucilage: a comprehensive review on sources, extraction, functional properties, health benefits, and emerging trends in food

Plant- and algal-derived mucilage has gained attention as a sustainable, multifunctional biopolymer for food and allied applications, driven by the demand for clean-label ingredients, green processing technologies, and alternatives to petroleum-based additives. Mucilage is a complex hydrocolloid matrix primarily composed of heteropolysaccharides (e.g. pectins, arabinoxylans, galactomannans, glucomannans, and alginates), associated proteins, and bioactive compounds that provide hydration, rheological, emulsifying, gelling, and film-forming properties. This review aims to provide a comprehensive and critical synthesis of information on plant and algal mucilage, focusing on sources, extraction strategies, chemical composition, structural–functional relationships, health attributes, and emerging trends in food applications. This review systematically evaluates mucilage obtained from seeds, leaves, fruits, roots, stems, and algal sources, with particular emphasis on how botanical origin and processing conditions influence functional performance. A comparative assessment of traditional extraction methods and modern green technologies, including ultrasound-assisted, microwave-assisted, enzyme-assisted, pulsed electric field, and cold plasma extraction is presented. Key findings demonstrate that advanced extraction techniques can significantly enhance yield, reduce processing time and solvent usage, and tailor molecular structures while preserving or improving functional attributes. Correlations between structure and function obtained from FTIR, NMR, SEM, and XRD analyses show that polysaccharide composition, branching degree, uronic acid content, and protein-polysaccharide interactions are critical factors influencing viscosity, WHC, OHC, emulsion stability, gel strength, and film integrity. This review provides information regarding health-related functions, such as prebiotic potential, glycaemic management, cholesterol reduction, antioxidant activity, and antibacterial properties, showing that mucilage is a beneficial ingredient for functional foods. An application-focused review highlights the effective integration of mucilage in dairy, bread, beverages, meat, and fresh produce sectors, along with its use in edible coatings, active packaging, and biodegradable films. In conclusion, plant and algal mucilage constitutes a flexible and renewable biopolymer with significant potential to enhance sustainable food technology. Addressing issues related to compositional diversity, scalability, standardization, and regulatory approval will be essential for industrial translation. Future research should emphasise hybrid formulations, nano-enabled systems, and integrated green processes in accordance with circular economy concepts.