In vitro simulated digestion and fermentation characteristics of pumpkin polysaccharides and their effects on the human gut microbiota

Abstract

Although pumpkin polysaccharides have numerous health benefits, limited studies have investigated the impact of pumpkin polysaccharide digestion and fermentation characteristics on its biological activity. Herein, pumpkin polysaccharides (PPs) were subjected to simulated saliva–gastric–small intestinal digestion, followed by in vitro fermentation using healthy human faecal microbiota. Results indicate that PPs, acidic heteropolysaccharide with a molecular weight of 2.93 × 10² kDa, mainly composed glucose and D–galacturonic acid and remained stable under simulated salivary and gastric conditions; however, they slightly degraded during intestinal digestion. During in vitro faecal fermentation, PPs stimulated the production of short–chain fatty acids, particularly acetic acid, which lowered pH, promoted the abundance of beneficial bacteria such as Lactobacillus, and inhibited harmful bacteria such as Escherichia–Shigella and Phascolarctobacterium. PICRUSt analysis suggested that the gut microbiota regulation of PPs was linked to metabolic pathways and amino acid biosynthesis, indicating the potential prebiotic properties and health benefits of PPs.