Digestive Property and Bioactivity of Blackberry Polysaccharides with Different Molecular Weights

In the present study, the digestion and fermentation of blackberry polysaccharides (BBPs) with different molecular weights (M_w) were investigated. The results showed that the M_w decrease rates of BBP, BBP-8, BBP-16, and BBP-24 were 77.48, 69.61, 56.87, and 52.89%, respectively. The antioxidant and α-glucosidase inhibitory activities of BBPs were decreased under gastrointestinal condition, which might be due to the variation of M_w during digestion. The bile acid-binding ability of BBPs showed an M_w-dependent manner for higher M_w polysaccharides with higher viscosity. Through fermentation, the BBPs affected the ecosystem of the intestinal tract by promoting the production of short-chain fatty acids, lowering the pH of colon, and decreasing the ratio of Firmicutes to Bacteroidetes. All BBPs showed almost a similar modulation effect on the gut bacteria, but the lower M_w polysaccharide was more easily utilized by bacteria.