Total phenolic content and antioxidant activities of edible flower tea products from Thailand

Tea is one of the most widely consumed beverages all over the world due to its beneficial health effects and special flavor and taste. Tagetes erecta, Telosma minor, Ixora coccinea, Nelumbo nucifera, Antigonon leptopus, Hibiscus rosa-sinensis, Bougainvillea glabra and Senna siamea are used as traditional edible and medicinal materials in Thailand. In this study, the total phenolic content and antioxidant capacities of these edible flower tea drinks were investigated. Each categories of tea were brewed at 90, 95 and 100 degrees Celsius for 3, 5 and 10 minutes to investigate the total phenolic content and antioxidant capacities at different brewing temperature conditions and times. The total phenolic content (TPC) was estimated as gallic acid equivalents by the Folin–Ciocalteu reagent method. The antioxidant activity was measured by ferric-reducing antioxidant power (FRAP). Results showed that tea drink of Tagetes erecta flowers brewed at 100 degrees Celsius for 3 minutes contained the highest level of total phenolic content, 35.446 (mg GAE/g DW). However, Tagetes erecta tea drinks brewed at 95 degrees Celsius for 5 minutes exhibited the highest total reducing capacity (Ferric Reducing Antioxidant Power, FRAP assay; 36.143 μmol FeSO4/g DW). This study has provided useful information for further research in edible flower tea products from Thailand.