The TFA content was determined by the aluminium chloride colorimetric method of Siddhuraju and Becker (2003). Briefly, 0.5 mL of sample (appropriately diluted) was placed in a 10 mL graduated test tube, 3.5 mL of distilled water and 0.3 mL of sodium nitrite (7.5 g/100 mL) were added and mixed. 3 mL of aluminium chloride solution (1 g/100 mL) was added after 5 min. 6 min later, 2 mL of sodium hydroxide solution (4 g/100 mL) was added, and the total volume was made up to 10 mL with distilled water and vibrated for 20 s. After 15 min, the absorbance was measured against a blank at 510 nm. The TFA content was calculated from a calibration curve of rutin and expressed as rutin equivalent (mg RE/g dry basis).