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 • 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 • 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 • 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 ) from QMETLJ . 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 from QMETLJ . © 2014 Society of Chemical Industry