Optimization of extraction parameters of phenolic antioxidants from defatted grape seed flour by response surface methodology

The response surface methodology (RSM) was used to search for the optimal conditions for solid-liquid extraction of phenolic compound from defatted grape seed flour under the influence of three factors: temperature (60-100 C) and time (90-150 minutes) of extraction, ratio of solvent to mass of powder ( 60-100).
The total antioxidant capacity (TAC) and the total content of polyphenolic compounds (TPC) of the samples were determined by coulometric titration in galvanostatic mode with electrogenerated bromine and spectrophotometric method using Folin-Ciocalteu reagent, respectively. Experimental values ​​of TAC and TPC were presented in terms of the equivalent of the content of gallstone (GAE) per unit mass of powder (DW).