Prebiotic potential of RG-I pectic polysaccharides from Citrus subcompressa by novel extraction methods

In the present study, the in vitro fermentation by human gut microbiota of alkali-extraction citrus pectin (AK) and high pressure-alkali-extraction citrus pectin (HPAK) were investigated. The monosaccharide composition analysis showed that both AK and HPAK had a high ratio of Rhamngalacturonan I (RG-I) structure. After 48 h of fermentation, 85%–86% of total carbohydrate was utilized by colonic microbiota. The pH value in the fecal fermentation liquid significantly decreased during fermentation. AK and HPAK significantly promoted the production of short-chain fatty acids, especially propionic and n-butyric acids. They also increased the abundance of potential beneficial genera (i.e. Bifidobacterium and Phascolarctobacterium) and decreased the abundance of potential harmful genera (Escherichia-Shigella and Klebsiella). All the results suggested that HPAK and AK are potentially sources of prebiotics in functional foods aimed at promoting gut health.