Determination of total phenolic content from commercially availableE thiopian black teas

Abstract

Tea is one of the most popular beverages in the world, is an infusion of the leaves of the tea plant, Camellia sinensis which is under the Theaceae family and the Camellia species (Camellia sinensis). The main types of tea are green tea, oolong tea, white tea and black tea. Among the four types, black tea is the most commonly consumed in the world. Therefore, the aim of this study was to determine total phenol content from some commercially available Ethiopian black tea. To find the best extraction condition, heat extractions were conducted at different solvent, temperature and time. Finally, the tea samples were analyzed for phenol content with Uv/Vis Spectroscopy at 760 nm. Under optimum conditions of 80% ethanol solvent ratio, 80°C temperature and extraction time of 15 minutes, the TPC found in Gumaro, Wush-wush and Back lion tea were 28.5 ± 0.96 mg GAE/g, 26.5 ± 0.82 mg GAE/g and 23 ± 0.24 mg GAE/g, respectively. From the three Ethiopian black teas Gumaro black tea have the highest total phenol content and black lion have the lowest phenolic content. The detection limit (LOD) and quantification limit (LOQ) were 1.3 and 3.8 mg GAE/g, receptively. Even if the samples were belong to the same black tea type, the level of TPC in the three tea type were significantly different (p<0.05) at 95% confidence interval. The possible reason for this difference total phenolic content could be different ways of tea cultivation, period of harvesting, different processing procedure, fermentation time and other process.