Abstract:

Pholiota dinghuensis Bi exopolysaccharides (PDEPS-1) was prepared from the fermentation broth of Pholiota
dinghuensis Bi through extraction and purification procedures. The changes of PDEPS-1 in simulated digestive juices were
investigated by determining the reducing sugar content, molecular weight, and monosaccharide composition before and after
digestion using simulated saliva, gastric juice and gastrointestinal juice model in vitro. The results showed that the content
of neutral sugar in PDEPS-1 was 97.97%, and PDEPS-1 also contained small amounts of protein, uronic acid, and sulfuric
radical. No reducing sugar was detected in PDEPS-1. The average molecular weight of PDEPS-1 was estimated to be
17.95 kD. It was composed of mannose and galactose in a molar ratio of 53.32:6.43. After digestion in saliva, the molecular
weight of PDEPS-1 remained unchanged and neither reducing sugar nor monosaccharides were detected, indicating that
PDEPS-1 could not be digested in saliva. After digestion, reducing sugar was detected in both simulated gastric juice and
gastrointestinal juice, but monosaccharides were not detected. Therefore, the exopolysaccharide PDEPS-1 from Pholiota
dinghuensis Bi was resistant to the digestive juices.

Key words: Pholiota dinghuensis Bi, exopolysaccharide, in vitro digestion, reducing sugar, molecular weight, monosaccharide