Effects of different sea buckthorn leaf tea processing technologies on nutrient level and fecal microflora in vitro

Three sea buckthorn leaf tea products, namely, tea dried at room temperature (SDRIED), conventionally processed green tea (SGREEN) and black tea (SBLACK), were compared for their effects on human fecal microflora and the levels of related nutrients. Content analysis confirmed higher total polysaccharides for SGREEN (165.8 + or - 0.1 g[middot]kg super(-1)) than for SBLACK (100.0 + or - 0.1 g[middot]kg super(-1)) and SDRIED (115.8 + or - 0.1 g[middot]kg super(-1)), higher total quercetin for SGREEN (6.0 + or - 0.2 g[middot]kg super(-1)) and SDRIED (7.7 + or - 0.2 g[middot]kg super(-1)) than for SBLACK (2.4 + or - 0.1 g[middot]kg super(-1)), and higher total gallic acid for SBLACK (0.60 + or - 0.01 g[middot]kg super(-1)) than for SGREEN (0.46 + or - 0.01g[middot]kg super(-1)) and SDRIED (0.07 + or - 0.01 g[middot]kg super(-1)). An in vitro digestion assay demonstrated that the order of nutrient contents remained unchanged after digestion. Furthermore, an in vitro fermentation assay indicated that only SGREEN treatment could increase the content of the probiotic Bifidobacterium and decrease the content of the pathogenic Clostridium perfringens simultaneously. These findings show that green tea processing technology is more suitable for making sea buckthorn leaf tea. For the first time, improved fecal microflora rather than antioxidant activity was selected to evaluate different leaf tea products.