Abstract: Gallotannins, esters of carbohydrates or polyols with gallic acid present in fresh fruit juice of Emblica officinalis and has been found to be pharmacologically active. The knowledge of dietary intake of gallotannins and their bioaccessibility in gastrointestinal track are key factors in assessing their significance in human health. This study illustrates a biotransformation of gallotannins from fruit juice in gastrointestinal fluids and analysis of bioactive marker by rhodanine assay. Total gallic acid was determined by rhodanine assay from fruit juice of Emblica officinalis. Gastric juice and intestinal fluid caused hydrolysis of fruit juice during incubation for 8 h. The hydrolysis product from fruit juice was gallic acid. In vitro studies indicated that dissociation of gallic acid from ester complexes was apparent in both the fluid but gallotannins were rapidly hydrolyzed in gastric juice rather than intestinal fluid. Thus, our data suggest that hydrolysis of gallotannin in gastrointestinal fluid produced gallic acid which is possibly responsible for pharmacological effects.