Advances in Enzymatic Production of Prebiotic Oligosaccharides from Agro-Industrial Waste: A Critical Review and Industrial Framework

Agro-industrial wastes are abundant, low-cost feedstocks used for the sustainable production of prebiotic oligosaccharides via enzymatic methods. This review summarizes recent advances, with particular emphasis on studies published after 2020, in the enzymatic valorization of these by-products, highlighting pretreatment strategies, enzyme classifications, and reaction conditions for converting complex substrates into functional prebiotic ingredients. In parallel, pioneering studies are recognized as foundational work, as they offer key mechanistic insights and continue to play a key role in supporting the interpretation of recent advances in the field. The functionality of the resulting prebiotic oligosaccharides, assessed through various in vitro models, is discussed, with emphasis on their impact on the technological performance of different food matrices. Evidence from in vitro and human studies further illustrates the biological activity and added value of waste-derived prebiotic oligosaccharides. While enzymatic technologies demonstrate high efficiency and selectivity, the full potential of many agro-industrial wastes for bioconversion remains underexplored. Optimizing enzymatic processes and systematically assessing functionality are essential in order to fully harness these resources, supporting the development of innovative, value-added food products within a circular bioeconomy. This review provides an integrated platform linking prebiotic oligosaccharide production, functionality, and food applications, promoting the valorization of agro-industrial waste into high-value prebiotic ingredients.