Microwave-assisted extraction of polyphenols from fresh tea shoot

Abstract

Fresh tea shoots (one shoot and two or three young leaves) were extracted using microwave-assisted extraction method (MAE). Several factors such as ethanol concentrations (0-99.5o (volume percentage)), material: solvent ratio (1:4 to 1:12), extraction time, oven power were studied to optimise conditions at laboratory scale. MAE archived good yield (82.46 %) after 6 minutes microwave radiation, that was higher than that of extraction at room temperature in 24 hours, conventional heating extraction at reflux temperature in 60 minutes or ultrasound-assisted extraction in 60 minutes. Afterward, MAE method was employed to investigate five types (LD97, LDP1, PH1, TB14, HAT) of tea (Camellia sinensis (L.) O. Kuntze) from Bao Loc, Lam Dong. HAT (20.49 % dried weight of total catechins) was found as suitable material for polyphenols extraction.