Abstract:Tea dietary fiber is a by-product of tea processing industry，which is beneficial for human body.However，the comprehensive utilization of tea dietary fiber is still not widely available at present.The physical and chemical properties of tea dietary fiber were evaluated by investigating water-holding，oil-holding and expansion ability，and its functional group structure and microstructure were characterized by scanning electron microscopy，infrared spectroscopy and X-ray diffraction.In vitro fermentation，tea dietary fiber could significantly increase the number of Lactobacillus and Bifidobacterium，while inhibit the number of Enterobacteria，Enterococcus and Clostridium perfringens.As the concentration of tea dietary fiber increased，the pH value of fermentation liquor decreased significantly.The variety and quantity of short-chain fatty acids（SCFAs）in fermentationweredeterminedby gaschromatography-massspectrometer（GC-MS）.With the increase of tea dietary fiber concentration，the SCFAs content increased continuously，with the highest content of acetic acid being（20.65±0.93）mmol/L，the highest content of propionic acid being（2.88±0.14）mmol/L，the highest content of butyric acid being（10.89 ± 1.01）mmol/L，and the highest content of lactic acid being（19.91 ± 1.38）mmol/L.Combined with the results of intestinal flora and SCFAs，2 % tea dietary fiber could be added as the optimal proportion，which was beneficial to the regulation of intestinal flora.