The total phenolic content was determined by the Folin-
Ciocalteu assay as described by Singleton, Orthofer, and Lamuela-
Raventos (1999) and expressed as mg of gallic acid equivalent
(GAE) per kg of dry matter (d.m.). One hundred mL of the extract
was transferred into test tubes and their volume made up to 500 mL
with distilled water. After addition of Folin-Ciocalteu reagent(250 mL) and 20 g/100 g aqueous Na2CO3 solution (1.25 mL), tubes were vortexed. The absorbance of the mixture was measured at
750 nm after 40 min.