Preparation, Characterization, and Anti-Colitis Activity of Low-Viscosity EDTA-Soluble Polysaccharides from Almond Gum.

Almond gum is a resource-rich natural polysaccharide; however, its high viscosity and low solubility severely limit industrial applications in separation, purification, and functional development. This study aimed to overcome these bottlenecks by optimizing an ethylenediaminetetraacetic acid (EDTA) preparation process and evaluating its protective efficacy against colitis. Using response surface methodology, optimal conditions were identified (1% EDTA, 3 h reaction, 10 h extraction), resulting in a modified polysaccharide (EAGP) with significantly reduced viscosity (from 640.8 to 238.7 mPa·s). SEM-EDX confirmed that EDTA efficiently removed cross-linking metal ions (K, Ca, Mg), creating a porous structure that facilitates purification. The purified fraction, EAGP-W1, was characterized as an arabinogalactan primarily composed of galactose (40.51%) and arabinose (38.38%). In vivo experiments demonstrated that EAGP-W1 significantly alleviated DSS-induced colitis, reducing colonic shortening and histopathological damage (p < 0.05). Mechanistically, EAGP-W1 reshaped the gut microbiota by downregulating pro-inflammatory genera and upregulating probiotics (p < 0.05). This shift promoted the production of short-chain fatty acids (SCFAs) (p < 0.05), thereby repairing the intestinal barrier and suppressing inflammation. Overall, this study establishes an efficient EDTA-based strategy for almond gum processing and elucidates its anti-inflammatory mechanism through the "microbiota-metabolite-barrier" axis, providing a theoretical basis for its development as a high-value functional food for gut health.