2.4. Determination of total flavonoid content
Total flavonoid content was determined by aluminium chloride
colorimetric assay (Marinova et al., 2005). The concentrations of
the sample and standard (catechins) solutions were 10 mg/ml
and 25, 20, 15, 10, 5 lg/ml, respectively. 25 ll of each sample or
standard reagent was mixed with 125 ll of DW, followed by addition
of 8 ll of 5% sodium nitrate solution. The mixture was incubated
at RT for 5 min. Ten percent aluminium chloride solution
was mixed with 15 ll of the above mixture. Finally, the absorbance
was measured at 517 nm. Total flavonoid content was expressed as
a percentage of the catechins equivalent (CE) per 100 g dry mass
obtained from the standard calibration curve.
of 20% sodium carbonate solution and incubated at RT for 30 min.
Finally, the absorbance was measured at 700 nm wavelength, with
a UV–visible spectrophotometer. Total phenolic content was determined
from the standard calibration curve. Results were expressed
as percentage of gallic acid equivalents (GAE) per 100 g dry mass.