Physicochemical characterisation and -amylase inhibitory activity of tea polysaccharides under simulated salivary, gastric and intestinal conditions

Tea polysaccharides (TPS) are one of the main components of tea with various bioactivities. Digestion could result in the changes of the physicochemical properties and bioactivities of polysaccharides. The objective of this study was to determine the changes in physicochemical properties and -amylase inhibitory activities of TPS after simulated digestion. The structure of TPS determined by UV, IR and SEM showed that no obvious changes after salivary digestion, but significant changes after gastrointestinal digestion were observed. After intestinal digestion, the contents of reducing sugar were increased from 0.650 +/- 0.011 to 1.594 +/- 0.078mm, and the centre molecular weight was decreased from 540.57 to 375.35KDa. The molar ratio of monosaccharide was changed after digestion. And -amylase inhibition rate was significantly increased (P<0.05). The results could provide information on the digestibility of TPSinvitro and contribute to the development of related functional foods or medicines.