Glucansucrases as versatile biocatalysts: structural insights, synthesis of emerging prebiotic oligosaccharides, and their functional roles in food matrices.

Glucansucrases (GSs), primarily members of the Glycoside Hydrolase family 70 (GH70), have emerged as transformative biocatalysts for the sustainable synthesis of high-value α-glucans and tailored oligosaccharides directly from sucrose. This review systematically explores the structural insights and catalytic mechanisms of these enzymes, emphasizing the molecular determinants of linkage specificity and domain organization. By leveraging advanced enzyme engineering and the strategic application of acceptor reactions, it is now possible to produce tailor-made prebiotic oligosaccharides with diverse glycosidic architectures. The integration of these custom polymers into functional food matrices is discussed not only for their nutritional contribution but also for their profound impact on techno-functional properties, such as rheology, texture, and shelf-life. Furthermore, the physiological significance of these emerging prebiotics is evaluated through the lens of selective microbiota modulation, gut barrier reinforcement, and overall metabolic health. Finally, this review navigates the transition from laboratory-scale synthesis to industrial application, addressing the techno-economic challenges and regulatory frameworks essential for commercialization. By bridging the gap between basic biocatalysis and food engineering, glucansucrases stand as pivotal tools for the development of next-generation, health-promoting functional foods.