In vitro digestion under simulated saliva, gastric and small intestinal conditions and fermentation by human gut microbiota of polysaccharides from the fruits of Lycium barbarum

In the present study, the digestion under simulated saliva, gastric and small intestinal conditions and in vitro fermentation by human gut microbiota of Lycium barbarum polysaccharides (LBPS) were investigated. As a result, LBPS contained carbohydrates, uronic acids, protein and polyphenols of 60.96 ± 5.58, 20.98 ± 2.49, 5.30 ± 0.12 and 1.04 ± 0.06%, respectively. Furthermore, LBPS was mainly consisted of glucuronic acid (5.12 mol%), galacturonic acid (12.40 mol%), glucose (2.15 mol%), galactose (39.67 mol%) and arabinose (40.66 mol%). Under simulated saliva, gastric and small intestinal conditions, LBPS was not affected. Whereas, LBPS could be utilized by gut microbiota based on the consumption of monosaccharides, decreased molecular weight and lower content of total carbohydrates after fermentation in vitro. With the proceeding of fermentation, LBPS significantly promoted the production of short-chain fatty acids. Meanwhile, LBPS could alter the microbial community after 24 h fermentation, especially enhancing the relative abundances of genera Bacteroides, Bifidobacterium, Phascolarctobacterium, Clostridium XlVb, Prevotella and Collinsella. All the results suggested that LBPS could be developed as special ingredients for modulating gut microbiota composition and promoting the growth of beneficial bacteria like Bifidobacterium.