Biocatalytic Production of Functional Oligosaccharides from Agricultural and Food Processing Residues: Toward Functional Oligosaccharide Production

Agricultural and food-processing residues represent abundant renewable feedstocks for the sustainable production of functional oligosaccharides through biocatalytic conversion. Valorization of these underutilized biomass resources represents a promising strategy for producing high-value bioactive oligosaccharides while improving resource efficiency and supporting the circular bioeconomy. This review discusses current developments in the biocatalytic synthesis of functional oligosaccharides from agro-food residues, with emphasis on residue-specific biocatalytic techniques and carbohydrate-active enzymes (CAZymes). Along with new transglycosylation and glycosynthase-based methods for the synthesis of structurally defined oligosaccharides, the catalytic mechanisms and substrate specificity of hydrolytic enzymes involved in the synthesis of xylo-, cello-, pectic-, and chitooligosaccharides are critically discussed. Recent advances in biocatalytic platforms, such as multi-enzyme cascade systems, whole-cell biocatalysis, and immobilized enzyme technologies, are highlighted as promising strategies for improving catalytic efficiency, product selectivity, and operational performance, together with future opportunities in enzyme engineering and computationally assisted biocatalyst development. This review offers a biocatalyst-centered perspective for the sustainable production of functional oligosaccharides and provides insights into the development of effective biomass valorization strategies for future industrial biorefineries by linking residue-specific biomass resources with current biocatalytic approaches.