Functional properties of herbal tea prepared from Cosmos Caudatus leaves at different maturity stages / Dian Nashiela Fatanah

Nowadays, supplementation of human diet with herbal tea is a worldwide trend because it is believed to offer positive potential health effects, giving negligible side effects, refreshing taste, relaxation and rejuvenation, besides, cheaper in price, abundant in resources and convenience to be consumed. However, different maturity stages of plants being used as raw materials constitute an important factor in influencing their antioxidant activity, phenolic compounds, mineral content, colour, mutagenic activity and sensorial properties. Hence, this study was designed to investigate the antioxidant content, antioxidant activity, mineral content, colour, mutagenic activity and sensorial properties of herbal tea prepared from Cosmos caudatus leaves at different maturity stages namely young, mature, old and mixed leaves. Comparison of these C. caudatus herbal teas with C. caudatus herbal tea from commercial brand was also conducted. All prepared C. caudatus herbal teas were analysed for total phenolic content (TPC), total flavonoid content (TFC), ferric reducing antioxidant power (FRAP), 2-2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, β-carotene bleaching assay, oxygen radical absorbance capacity (ORAC), high performance liquid chromatography (HPLC) analysis of phenolic compounds, mineral content, colour, Ames test as well as quantitative descriptive analysis (QDA). The results demonstrated that, C. caudatus herbal tea prepared from young leaves had significantly strong (p<0.05) antioxidant activity compared to other C. caudatus herbal teas for all assays tested. Pearson‘s correlation coefficient also revealed that, TPC and TFC exhibited a strong correlation with all antioxidant activity assays, indicating that these compounds are the major contributors to the antioxidant activity in C. caudatus herbal teas. Out of fourteen phenolic compounds analysed, twelve phenolic compounds were detected in all C. caudatus herbal teas with the amount reduced significantly (p<0.05) as maturity increased. Nevertheless, the mineral content in C. caudatus herbal teas increased as maturity increased. Corresponded to the results of antioxidant activity and mineral content, C. caudatus herbal tea prepared from young leaves had significantly darker colour compared to other C. caudatus herbal teas. The Ames test showed that, none of C. caudatus herbal teas induced any increased in the number of revertants, demonstrating the absence of mutagenic activity. In terms of overall acceptability, C. caudatus herbal tea from commercial brand was the most preferred by the panelists. Hence, due to the beneficial constituents presence in all C. caudatus herbal teas prepared from leaves at different maturity stages, further investigation should be conducted to improve on the taste of these herbal teas as well as to study on their the antimutagenic activity.