Effective Enzymolysis of Xanthan under High Temperatures Facilitates Its Addition as a Novel Dietary Fiber

The inherently high viscosity of xanthan has constrained its utility as a dietary fiber in various applications. In this study, a novel enzymatic strategy was established by employing two thermostable xanthanases (Xan12E and XanVA) to generate low-viscosity xanthan derivatives. Structural and molecular dynamics analyses revealed Xan12E's superior thermal resilience (no melting temperature ≤ 95 °C) and lower conformational fluctuations compared to XanVA. Under high temperatures, Xan12E exhibited a catalytic activity of 247.1 U g^-1, representing a 1.5-fold increase compared to XanVA. Enzymolysis using Xan12E resulted in a 19.7-fold reduction in viscosity, accompanied by a substantial decrease in the molecular weight from 3.4 × 10⁶ to 1.0 × 10⁵ Da while retaining the key functional groups essential for xanthan's bioactivity. The enzymatically modified xanthan exhibited notable antioxidant activity with IC₅₀ values ranging from 0.5 to 5.8 g L^-1. Furthermore, it exerted pronounced anti-inflammatory effects in macrophages, suppressing the expression of COX-2, TNF-α, IL-1β, iNOS, and IL-6 at 100 μg mL^-1. This study establishes high-temperature enzymolysis using Xan12E as a scalable, eco-friendly method to produce low-viscosity xanthan with enhanced bioactivity, addressing a critical gap in functional food additives and expanding xanthan's applications in the food industry.