Development of Herbal Green Tea Bags with Osbeckia octandra L. (DC.) (Heen bovitiya) and Evaluation of the Effect of Infusion Time and Temperature on Extracted Phytochemicals

Abstract

Herbal tea or a tisane is a mixture of dried plant parts used for medicinal purposes. Present study was aimed to develop herbal green tea bags with Osbeckia octandra (Heen bovitiya) leaves predominantly and evaluate the effect of infusion time and temperature on their total phenolic (TP), total flavonoid (TF) contents and in vitro antioxidant activity. Six different tea bags (T1 to T6) were prepared by incorporating dried O. octandra (leaves), Camellia sinensis (leaves), Zingiber officinale (rhizomes), Vanilla planifolia (pods) and Allium sativum (bulbs) in different proportions. Each herbal tea bag was infused at a constant infusion temperature of 100 ⁰C for 3, 5 and 7 minutes and for a constant infusion time of 7 minutes at different temperatures; 100, 90 and 80 ⁰C. TP, TF contents, in vitro radical scavenging activity and ferric reducing antioxidant power of all tea extracts were determined by spectroscopic analysis. Data were analyzed with one sample t test. All infusions were rich in phytochemicals; phenols, flavonoids, tannins, terpenes, triterpenoids, phytosterols, saponins, alkaloids, amino acids and carbohydrates. TP, TF contents and in vitro antioxidant activity of the formulated tea bags were significantly higher after the addition of O. octandra leaves and the values were different at different infusion conditions (p<0.05). At constant infusion time of 7 minutes, TP, TF contents and antioxidant activity of O. octandra incorporated green tea bags were higher when infused at 80 ⁰C compared to 90 ⁰C and 100 ⁰C. At constant infusion temperature of 100 ⁰C, the values were higher for the formulated green tea bags when infused for 7 minutes compared to 3 and 5 minutes. Hence, it was concluded that the formulated tea bags with O. octandra leaves were rich with antioxidants and that they should be brewed for a long time period (7 minutes) at a low temperature (80 ⁰C).