Effect of Extraction Conditions of Green Tea on Antioxidant Activity and EGCG Content: Optimization using Response Surface Methodology

Abstract

− Green tea, the leaves of Camellia sinsneis (Theaceae), is generally acknowledged as the most consumed beverage with multiple pharmacological functions including antioxidant activity. This study was performed to analyze the effect of extraction conditions of green tea on its antioxidant effects using DPPH assay. Three extraction factors such as extraction solvent (EtOH, 0 -100%), extraction time (3 -15 min) and extraction temperature (10 -70 o C) were analyzed and optimized extraction condition for antioxidant activity of green tea extract (GTE) was determined using response surface methodology with three-level-three-factor Box-Behnken design (BBD). Regression analysis showed a good fit of data and the optimal conditions of extraction were found to be 57.7% EtOH, 15 min and 70 o C. Under this condition, antioxidant activity of experimental data was 88.4% which was almost fit to the ideal value of 88.6%. As epigallocatechin gallate (EGCG) is known for the major ingredient for antioxidant activity of green tea, we investigated the effect of EGCG on antioxidant activity of GTE. EGCG showed antioxidant activity with the IC 50 value of 4.2 µg/ml and a positive correlation was observed between EGCG content and the antioxidant activity of GTE with R² = 0.7134. Interestingly, however, GTE with 50 -70% antioxidant activity contain less than 1.0 µg/ml of EGCG, which is much lower than IC 50 value of EGCG. Therefore, we suppose that EGCG together with other constituents contribute to antioxidant activity of GTE. Taken together, these results suggest that green tea is more beneficial than EGCG alone for antioxidant ability and optimal extraction condition of green tea will be useful for the development of food and pharmaceutical applications

Optimization of Hot-water Extraction of Dried Yacon Herbal Tea Leaves: Enhanced Antioxidant Activities and Total Phenolic Content by Response Surface Methodology

“…For example, the optimum condition for efficient extraction of rosmarinic and carnosic acids and carnosol from rosemary is ethanolic-water extraction for 55 min (Oliveira et al, 2016). The optimum condition for high TPC from Henna leaves is 48.07 % acetone extraction for 73.87 min at 39.57 ℃ (Uma et al, 2010), while that of high antioxidant activities with higher amounts of epigallocatechin gallate from green tea (Kim et al, 2016) is 57.7 % ethanol extraction for 15 min at 70 ℃. To gain insight into the optimum industrial setting for the extraction of yacon herbal tea, wider ranges of time and temperature could be further investigated in future research.…”

Processing Technologies for the Extraction of Value-Added Bioactive Compounds from Tea

“…Gallocatechin and epigallocatechin were the major phenolic compounds of TFPB. In another study, Kim et al [ 116 ] evaluated the optimization of the TPC, antioxidant activity, and EGCG of green tea leaves at different ethanol concentrations (0–100%), extraction times (3–15 min), and extraction temperatures (10–70 °C). The maximum antioxidant activity (88.4%) was obtained using 57.7% ethanol at 70 °C for 15 min.…”

Optimized green extraction conditions of matcha green tea (Camellia sinensis) using central composite design for maximal polyphenol and antioxidant contents

“…"Extraction of matcha green tea," BioResources 16(2), 3255-3271. 3268 (Kim et al 2016). Different amount and type of compound present in green tea were influenced by extraction technique and conditions.…”