Total phenolics are quantitated by the Folin-Ciocalteu colorimetric assay. This assay is based on the oxidation of the phenolic compounds and the reduction of the Folin-Ciocalteu color reagent. When the Folin-Ciocalteu reagent is reduced it changes color from yellow to blue. The extent of this color change is measured by absorbance at 725 nm. Results are expressed in mg gallic acid equivalents per gram of sample (mg GAE/g).
Please see Sampling and Preparation under Plants for specific drying instructions.