Abstract:Tea powder contains a variety of biologically active ingredients，including polyphenols，theanine，dietary fiber，and polysaccharides.People tend to view teas made from tender shoots as highest quality，however，they seldom concern themselves with probiotic differences between tea powders resulting from differences in harvest time.To explore the probiotic characteristics of tea powders harvested at different times，this paper analyzes the basic components of green tea powder from three different harvesting periods（tender shoot，medium tender，and coarse）.Variations in microbial populations and short-chain fatty acids （SCFAs）produced in 24 h in vitro fermentations were measured to identify effects on the gut microbiota.The polyphenol，total free amino acid，and main catechin contents decreased，while theanine，dietary fiber，and polysaccharide content increased with decrease in tea powder tenderness.All three types of tea powder can influence the composition and abundance of intestinal flora.Tea powder can promote proliferation of beneficial bacteria including Lactobacillus，Bifidobacteria，and Bacteroides，with coarse tea having the most potent effect.Tea powder inhibited the growth and reproduction of Escherichia coli，Clostridium perfringens and Enterococci.Tea powder also increased levels of SCFAs produced by the gut microbiota，with coarse tea being the most effective.