Optimization of brewing conditions in epigallocatechin-3-gallate (EGCG) extraction from Jinxuan summer green tea by response surface methodology

The extraction conditions of epigallocatechin-3-gallate (EGCG) from Jinxuan summer green tea and antitumor activity against human gastric cancer SGC-7901 cells of the green tea extracts were investigated. On the basis of a single factor experiment, Box-Behnken design and response surface methodology were employed to optimize the hot water extraction conditions. The optimal extraction conditions for EGCG were determined as: extraction temperature of 85 °C, extraction time of 34 min, water-tea ratio of 41 mL/g, a solution of pH 6, and extraction twice. Under these conditions, the experimental extraction yield value of EGCG was 33.82 mg/g, which was not significantly different in comparison to predicted values. The results indicated that the regression models were suitable for the EGCG extraction from Jinxuan summer green tea. The summer green tea extract prepared under the optimal conditions had a higher antitumor activity against human gastric cancer SGC-7901 cells than the green tea extract made with traditional tea brewing method