Optimising the extraction of tea polyphenols, (−)‐epigallocatechin gallate and theanine from summer green tea by using response surface methodology

Summary In this study, response surface methodology was applied to determine the optimal conditions for the extraction of tea polyphenols, EGCG and theanine from summer green tea. As results, the optimal extraction conditions were determined to be temperature 96 °C, time 40 min and ratio of water to raw material 16 mL g−1. Under these optimal conditions, the experimental values for tea polyphenols, EGCG, theanine and IC50for DPPH free radical scavenging activity were 133.41 ± 3.12 mg gallic acid g−1, 30.23 ± 1.22, 3.99 ± 1.13 mg g−1and 724.95 ± 15.12 μg mL−1, respectively. There was no statistical difference at significant level of 0.05 between the experimental and predicted values. The results suggested that the regression models were accurate and adequate for the bioactives extraction from summer green tea.