Sequential Green Extraction of Caffeine and Catechins from Green Tea

Abstract

Separation of caffeine and catechins from tea extracts usually requires conventional liquid-liquid extraction employing chloroform. This work was planned to improve a green extraction technique to distunguish these important chemicals from green tea. Extraction of caffeine and catechins from Turkish green tea firstly employing MAE, and then to separate these compounds from each other using a SFE method were purpose of this study. Microwave assisted extraction was applied to extract tea components from green tea then i) conventional liquid-liquid extraction or ii) supercritical carbon dioxide fluid extraction (SFE) method was charged with the effective separation of caffeine and catechins. Initially, an ethanol: water mixture was used in a close microwave system under the particuler extraction situations of green tea samples (fresh, frozen or dried) picked up in three collection periods (first, second and third collection periods). MAE of tea samples was exerted under a controlled 600 W microwave power for 4 min irradiation time at 80  C temperature. Then MAE crude aqueous extract was divided in to two portions. The first portion was fractionated first with chloroform to distunguish caffeine then ethyl acetate for catechins. Caffeine and catechins were successfully separated. Second portion was freeze-dried and obtained lyophilized solid was used for SFE. Caffeine (3.68% extract yield) was successfully separated from catechins with SFE at 250 bar and 60°C for 180 min. Constituents of the extracts were determined (caffeine and four catechins namely EGC, EC, C, EGCG) by HPLC to evaluate the effectiveness of the separation.

Comparing the application of conventional and supercritical CO 2 extracts of green tea; storage stability and sensory acceptance of coriander sauce

“…Recently, aqueous ethanol, acetone, and ethyl acetate were compared to extract green tea polycatechins, and it was found that acetonic extract of green tea possesses maximum extraction of polyphenols, i.e., 1,325.81 ± 64.85 mg GAE/100 g followed by ethanol and ethyl acetate as viewed in the current study (Ashfaq et al, 2019). Another group of researchers mentioned that catechins in supercritical fluid extract of green tea were 60.56 mg/g at 2,900 psi and 60°C (Serdar et al, 2019). Moreover, purity of EGCG in total polyphenol content of green tea was in the range of 70.7% to 76.5% at varied temperature, pressure, pH, and flow rate-like conditions (Mondal & De, 2018).…”

Supercritical Fluid and Ultrasound‐assisted Green Extraction Technologies for Catechin Recovery

“…In green tea samples worked upon, catechins were present in the order of amount as epigallocatechin > epigallocatechin gallate > epicatechin > catechin. Among 10, 20, 25 and 30 MPa tested, 25 MPa provided highest yield [36]. This indicates that regulated pressure plays a role in extraction efficiency, and not only a ramp.…”

“…Similar sequential extraction has been conducted by Serdar et al wherein optimized separation conditions were 60 °C, 250 MPa, 180 min, ethanol as modifier at 0.5 mL min -1 flow rate from Turkish green tea sample. The total run time was 3 h for caffeine and 3 h for catechin, i.e., in total 6 h for complete catechin extraction, per double run (direct method) [36]. These authors however contemplated using microwave treatment first, since it is way briefer than SC-CO 2 in process time, and the mixed yield could be separated post extraction by SFE.…”