COMPARISON OF THE COMPOSITION AND ANTIOXIDANT CAPACITIES OF GREEN TEAS PRODUCED FROM THE ASSAM AND THE CHINESE VARIETIES CULTIVATED IN THAILAND

Abstract

Tea (Camellia sinensis L.) has attracted much attention due to the antioxidant capacities of bioactive compounds present in it, which are considered beneficial to consumer health. In Thailand, commercially cultivated teas are the Assam and the Chinese cultivars which both are processed as green teas. The aim of this study was to investigate the chemical composition and antioxidant capacities of these teas. Samples were collected from tea factories and analyzed for caffeine content (CF), total polyphenol content (TPC), total catechin content (TCC), (-)-gallocatechin (GC), (-)-epigallocatechin (EGC), (+)-catechin (C), (-)-epicatechin (EC), (-)-epigallocatechin gallate (EGCG), (-)-gallocatechin gallate (GCG), (-)-epicatechin gallate (ECG), (-)-catechin gallate (CG), the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity (DPPH-assay) and the ferric reducing antioxidant power (FRAP-assay). The results showed that green tea produced from the Assam cultivar was significantly higher in CF and TPC than the Chinese cultivar. There was no significant difference in the TCC. Both cultivars had the same level of radical scavenging capacity (DPPH). As opposed to the radical scavenging capacity, there was a significant difference in the reducing power capacity (FRAP). The FRAP of the Assam was significantly higher than that of the Chinese tea. There was a significant difference in the individual catechins; the Assam cultivar mainly contained ECG, EGCG, and EC, whereas the major catechins in the Chinese cultivar were EGCG and EGC. Results from this study suggest that the profiles of catechins in green teas manufactured in Thailand might contribute to the cultivars.