Effect of the Infusion Time of Herbal Tea on Active Constituents Contents in Three Herbal Plants

Abstract

The purpose of this research was investigated the effect of infusion times on total active constituents such as phenolic, flavonoid and tannin and to study antioxidative activity of 3 herbal plants, including Plukenetia volubilis L. (Sacha inchi), Gymnanthemum extensum L. (Bitter leaf tree) and Garcinia atroviridis (Garcinia). All leaves were dried with oven at 50^๐C for 48 h, then leaves samples were coarsely ground and packed in 1 gram per a tea bag. Tea samples were infused in 100 ml of boiling water at 100^๐C for 2, 4, 6, 8 and 10 min. The results showed that color intensity of teas was detected by using colorimeter and representation of color with L*, a* and b* values. Three herbal teas were visualized in a low brightness color with yellow-brown for Sacha inchi and Bitter leaf teas and pink-brown for Garcinia leaf tea which the level of color has increased with increasing the brewing time. The contents were analyzed by using spectrophotometric method. At 10 minutes, the contents of these active constituents in three herbal teas were significant highest (p<0.05). Phenolic and flavonoid contents in Sacha inchi leaf were 20.33±0.12 and 3.39±0.04 mg/g.dw, respectively, that were higher than Bitter leaf and Garcinia leaf. In addition, tannin content in Bitter leaf was highest level with 3.01±0.11 mg/g.dw.   Moreover, antioxidative activity was tested at 10 min after infusion time by following the method of 2,2-diphenyl-1-picrylhydrazyl (DPPH) redical scavenging activity assay. The result showed that antioxidant potential of three herbal teas (Sacha inchi leaf, Bitter leaf and Garcinia leaf teas) was 82.26% 81.82% and 68.55%, respectively. Thus, this result indicated that the infusion time of three herbal teas caused significant enhance in contents of these active constituents which significantly correlated with the color variation of leaves tea and capacity of antioxidants.