Enhancing Antioxidant Activity of Miang Extract

The enhancement of antioxidant activity of the Miang extract was investigated by employing the ultrasonic-assisted tannase treatment. After the optimal conditions were established for the extraction of Miang, the obtained extract was immediately treated with tannase derived from S. ruineniae A45.2. Here, optimal levels of tannase, temperature, and time were investigated using CCD. Five values for tannase (500, 898, 750, 601, and 1000 mU/g tea), temperature (30, 34, 40, 46, and 50 °C), and time (5, 10, 17.5, 25, and 30 min) (Table 1S) were set in order to generate 14 treatment combinations with six center points, thus resulting in a set of 20 conditions being established for the treatment of Miang extract with tannase. After the treatment of Miang extract with tannase, the DPPH and ABTS radical scavenging activities obtained from each treatment combination were determined and expressed as μmol Trolox equivalent (TE)/g dw. Statistical analyses of the response variables were performed as has been previously described. Miang extract obtained from different extraction methods (Section 2.4) was treated with tannase by employing the optimal conditions. The contents of catechins, caffeine, and gallic acid obtained from all treated Miang extracts were determined by HPLC.