Catechin concentrates of garden tea leaves (Camellia sinensis L.): extraction/isolation and evaluation of chemical composition

BACKGROUND: Solid-liquid (SLE) and liquid-liquid (LLE) extraction techniques were applied to extract catechins and caffeine from quick mechanically expelled tea leaf juice (QMETLJ) and freeze-dried (FD)-QMETLJ of Camellia sinensis L. The concentrates obtained were analyzed for total polyphenol content and antioxidant activity (DPPH center dot inhibition, FRAP and phosphomolybdenum assay). Catechins were identified and quantified using HPLC. RESULTS: Overall, 95% (v/v) ethanol was the best solvent system for extracting total polyphenols (355.26 +/- 23.68 to 457.89 +/- 28.94 g GAE kg(-1) extractable solid yield (ESY)) and antioxidants (DPPH center dot inhibition, 16.97 +/- 0.52 to 20.83 +/- 3.11%; FRAP, 4.15 +/- 0.32 to 6.38 +/- 0.57 mmol TE g(-1) ESY; Mo(V) reduction, 2.47 +/- 0.19 to 3.84 +/- 0.39 mmol AAE g(-1) ESY) from FD-QMETLJ. Similarly, in LLE, ethyl acetate showed the best results for recovering polyphenols (960.52 +/- 7.89 g GAE kg(-1) ESY) and antioxidants (DPPH center dot inhibition, 42.39 +/- 0.91%; FRAP, 11.39 +/- 0.83 mmol TE g(-1) ESY; Mo(V) reduction, 6.71 +/- 1.14 mmol AAE g(-1) ESY) fromQMETLJ. CONCLUSION: It was found that 95% ethanol can be used to increase the total polyphenols and antioxidants in extracts from FD-QMETLJ, while ethyl acetate can be effectively employed for concentrating catechins fromQMETLJ. (C) 2014 Society of Chemical Industry