De-starched Panax ginseng polysaccharide: Preparation, in vitro digestion, fermentation properties and the activating effect of the resultant products on RAW264.7 cells

Panax ginseng C. A. Meyer (ginseng) neutral polysaccharides have been proven to be an immune enhancer, but their digestion and fermentation characteristics are unclear. This study aimed to prepare a de-starched polysaccharide (DGPN) from ginseng and investigate its degradation rules and the changes in immune activity by using an in vitro digestion and fermentation model. Results showed that in digestion process, the molecular weight of DGPN decreased from 4.72 × 10⁴ to 4.04 × 10⁴ Da, reducing sugar (C_R) content increased from 0.0539 ± 0.0037 to 0.0919 ± 0.0015 mg/mL. During the fecal fermentation process, a significant decrease in total carbohydrate content and molecular weight, a significant increase in C_R and change in the proportion of monosaccharide composition can be observed, indicating that DGPN was mainly degraded during fermentation process. DGPN modulated the microbial composition via increasing the relative abundance of beneficial bacteria including Bacteroides, [Eubacterium]_nodatum_group, Ligilactobacillus, Enterococcus and reducing harmful bacteria such as Escherichia_Shigela. DGPN also promoted the production of short chain fatty acids. Cell experiments results showed that fermentation product DGPN-F48 activated RAW264.7 cells via TLR4/Myd88/NF-κB signaling pathway and the activity was significantly enhanced after fermentation process. This study confirmed DGPN is beneficial for enhancing gut health and has prebiotic potential.