Effect of extraction temperatures on tannin content and antioxidant activity of Quercus infectoria (Manjakani)

This study was specifically aimed to investigate the effects of extraction temperatures on tannin and antioxidant activity; the interaction between these two responses towards the processing parameter chosen. The main bioactive compound; tannin was extracted from Quercus infectoria (Manjakani) galls using aqueous decoction method. Few different extraction temperatures were selected prior for the extraction of tannin from Q. infectoria galls optimally. The selected temperatures were at 50, 75 and 100 degrees C and the effects of these temperatures on tannin content and antioxidant activity were examined thoroughly. High Performance Liquid Chromatography (HPLC) was used to identify and quantify the active compounds mainly tannic acid found in Q. infectoria galls. Alternatively, DPPH radical scavenging assay was performed to analyse the antioxidant activity and trends affected from the extraction temperature. The results demonstrated that Q. infectoria aqueous extract gives the highest tannin concentration of 2233.82 +/- 1.311 and highest antioxidant activity approximately at 93.422 +/- 0.256% at the extraction temperature of 75 degrees C. The outcomes of this study illustrate that extraction temperatures gave significant effects on the response variables (tannin content and antioxidant activity) respectively and the interaction between these responses were considered.