Targeted Preparation of Low-Degree Polymerization Xylooligosaccharides From Lignocellulosic Biomass: Advances, Structure-Activity Relationships, and Applications.

Xylooligosaccharides (XOS) are highly promising functional prebiotics with excellent stability and intestinal regulatory activity, whose physiological efficacy is strictly dependent on their degree of polymerization (DP), with low-DP XOS (DP 2-3, mainly xylobiose and xylotriose) being the core active components. Recent advances in lignocellulosic biorefinery and enzymatic engineering have greatly expanded XOS feedstock sources and improved production efficiency, while the controllable preparation and efficient application of high-purity low-DP XOS remain the core bottleneck restricting the high-quality development of the XOS industry. This review systematically summarizes the latest research progress of lignocellulose-derived XOS, covering feedstock screening and evaluation, preparation technology comparison, DP-dependent functional mechanisms, and multi-scenario application advances. It highlights the unique advantages of mild organic acid pretreatment combined with specific enzymatic hydrolysis in low-DP XOS production, and the broad application prospects of low-DP XOS in precision nutrition and biomedicine, providing a comprehensive theoretical reference for subsequent research. Emerging promising approaches include continuous-flow reactors with real-time DP monitoring and high-specificity GH11 xylanase engineering, while future research will focus on targeted synthesis of specific DP XOS, in-depth dissection of molecular action mechanisms, and development of customized functional products.