Determination of the total phenolic content of commercially available green teas using an in vitro gastrointestinal system: a preliminary study

Abstract

This preliminary study evaluated changes in total phenolic content and catechin and epicatechin levels in commercially available green teas through an in vitro digestion. Samples (1.5% dry tea in 100 mL water at 80 degrees C) were analyzed for total soluble solids, pH, and color. The initial total phenolic content ranged from 381.19-1779.50 mu g gallic acid equivalent/mL, decreasing to 315.22-1266.37 mu g/mL in the small intestine. Epicatechin decreased from 7.64-13.97 mu g/mL to 4.53-9.19 mu g/mL, while catechin dropped from 13.13-24.03 mu g/mL to 5.43-14.03 mu g/mL. Significant decreases occurred across digestion, indicating reduced bioaccessibility of green tea polyphenols that may influence antioxidant and health effects.