In vitro Digestion and Fermentation Characteristics of Polysaccharides from Camellia nitidissima Chi

Polysaccharides were isolated from Camellia nitidissima Chi by water extraction and alcohol precipitation, then the polysaccharide extract was separated and purified by using DEAE-52 cellulose chromatography column. The digestion characteristics of the polysaccharides were studied in vitro by employing a simulated upper gastrointestinal model and analyzing molecular weight, reducing sugar and free monosaccharide ontents of digested products at different digestion times. The fermentation characteristics of polysaccharides were studied in vitro by using human fecal fermentation model and analyzing pH, total sugar, reducing sugar and short chain fatty acid content, as well as the Lactobacillus, Bifidobacterium and Escherichia coli number. The results showed that, TPS1, TPS2, and TPS3 were obtained after purification of the polysaccharide from Camellia nitidissima Chi. During in vitro digestion, the molecular weight of TPS1, TPS2, TPS3 and the reducing sugar content did not changed by simulated saliva and simulated intestinal juice. Simulated gastric juice caused a slight decrease in the molecular weight of TPS1, TPS2, and TPS3, and the content of reducing sugar increased from 0.129±0.016, 0.155±0.026, 0.147±0.017 mmol/L to 0.223±0.018, 0.319±0.013, 0.294±0.030 mmol/L. Free monosaccharides were not detected during the digestion. During the fermentation process, the pH of the group added with TPS1, TPS2, and TPS3 was significantly lower than that of the blank control group, the sugar consumption rate was 91.4%, 89.0%, 94.5%, and the reducing sugar content increased during 0~18 h, reduced during 18~48 h. Compared with the blank control group, the levels of acetic acid, propionic acid, and butyric acid were all significantly increased and the order of increasing multiple size was TPS3>TPS2>TPS1. Further, TPS1, TPS2 and TPS3 could promote the growth of Lactobacillus and Bifidobacterium, inhibit the growth of Escherichia coli, and the order of probiotic effects was TPS3>TPS2>TPS1. In summary, the polysaccharides were isolated from Camellia nitidissima Chi were not digested in vitro, and could be used by fecal microflora to produce a large amount of acetic acid, propionic acid and butyric acid, which had potential probiotic effects. And TPS3 had better probiotic effects than TPS2 and TPS1.