Polysaccharides are biological macromolecules that are difficult to absorb into intestinal epithelial cells for exerting activities, whereas the interaction between polysaccharides and gut microbiota might be an alternative method. This study aimed to explore the in vitro digestion of hawthorn polysaccharides (HPS) and their interaction with the gut microbiota. Results showed that the content of reducing sugars increased slightly during gastric digestion. However, no free monosaccharide was detected during the whole simulated digestion process, indicating that HPS was indigestible. The total carbohydrate residue decreased during in vitro fermentation. This result was due to the utilization by the gut microbiota. Meanwhile, short-chain fatty acids were produced due to the utilization of HPS. Notably, HPS could significantly modulate the composition of human gut microbiota; in particular, the relative abundances of Megasphaera, Acidaminococcus and Mitsuokella increased, whereas the relative abundances of Escherichia Shigella and Fusobacterium decreased. It was suggested that HPS could decrease the abundances of harmful intestinal microbiota and regulate the proportion of beneficial bacteria in the intestinal tract. Overall, the beneficial effects of HPS were believed to be related to the gut microbiota and could be used as a potential dietary supplement.

The interaction between polyphenols and polysaccharides plays an important role in increasing the turbidity stability of fruit juice and improving unpleasant sensory experiences. The binding adsorption behavior between hawthorn pectin (HP) and polyphenols (epicatechin and chlorogenic acid) accorded with the monolayer adsorption behavior driven by chemical action and were better fitted by pseudo-second order dynamic equation and Langmuir model. The HP binding sites (Q_m) and adsorption capacity (Q_e) to epicatechin were estimated at 75.188 and 293.627 μg/mg HP, respectively, which was about nine and twelve times higher than that of chlorogenic acid. The interaction between HP and polyphenols exhibited higher turbidity characteristics, particle size and lower zeta potential than epicatechin and chlorogenic acid alone. Meanwhile, according to Fourier Transform Infrared Spectroscopy (FT-IR) analysis, it could be speculated that the interaction between HP and polyphenols resulted in chemical combination. Moreover, ΔH < 0 and TΔS < 0, which indicated that the interaction between HP and polyphenols was mainly driven by hydrogen bonds and van der Waals forces.