Effects of ultrasound-assisted extraction procedure on total phenolics, catechin and caffeine content of green tea extracts

This study was conducted to investigate the changes encountered in water soluble dry matter (degrees Brix), total phenolics, caffeine and some important catechins of green tea extracts extracted through ultrasound-assisted extraction procedures. Extractions were conducted at 70 degrees C temperature, different tea: water ratios (5:100; 10:100) and brewing times (5, 10 and 20 min) and resultant extracts were also supplemented with tannase enzyme. Total phenolics of green tea extracts varied between 2.68 - 3.87 g GAE/100 g dry green tea. The greatest total phenolics (3.87 g GAE/100 g dry green tea) was obtained from 20 min brewing at 70 degrees C and 10:100 tea: water ratio of tannase enzyme-supplemented extract. As compared to the control samples, decreasing EGCG and ECG contents and increasing EGC and EC contents were observed with tannase enzyme supplementations.