2.4. Analytical methods
2.4.1. Determination of total phenol contents (TPC)
Total phenolic compounds were determined colorimetrically at 765 nm and expressed as gallic acid equivalent (GAE),according to the method described by Singleton et al. (1999).The samples were added to Folin-Ciocalteu reagent and Na2CO3 solution and placed in a water bath at 40◦C for 30 min before spectrophotometric analysis (spectrophotome-ter Genesys 10uv screening, Thermo Electron Corporation,France). Total phenol content was expressed as mg of gallic acid equivalent (GAE) per kg of dry matter (DW).