Effect of Sequential Extraction Methods on the Structure and In Vitro Fermentation Characteristics of the Polysaccharides from Sea Buckthorn Pomace

Polysaccharides derived from sea buckthorn pomace are bioactive compounds that can undergo intestinal fermentation and exert prebiotic effects. However, the influence of sequential extraction on their structural properties and prebiotic activity remains unexplored. Six fractions were sequentially extracted with water (W), CDTA (CA), sodium carbonate (SC), and 0.1, 1, and 4 mol/L NaOH (SH0.1, SH1, SH4), and their fermentation characteristics were compared by using an in vitro fecal fermentation model. SH1 and SH4 were enriched in glucose and xylose, whereas CA and SC contained more galactose, arabinose, and rhamnose, indicating they were pectic contributions. CA and SC markedly increased acetate and propionate production, while SH0.1, SH1, and SH4 favored propionate accumulation. All fractions enriched Parabacteroides; Bacteroides was more abundant in the CA and SH1 groups, and Bifidobacterium was most abundant in the W group. These findings indicate that compositional differences among polysaccharide fractions influence gut microbial composition and SCFA production.