Supercritical Fluid Extraction of Phenolic Compounds and Antioxidants from Grape (Vitis labrusca B.) Seeds

Supercritical fluid extraction (SFE) technique was applied and optimized for temperature, CO2 pressure and ethanol (modifier) concentration using orthogonal array design and response surface methodology for the extract yield, total phenols and antioxidants from grape (Vitis labrusca B.) seeds. Effects of extraction temperature and pressure were found to be significant for all these response variables in SFE process. Optimum SFE conditions (44 similar to 46 A degrees C temperature and 153 similar to 161 bar CO2 pressure) along with ethanol (< 7 %) as modifier, for the maximum predicted values of extract yield (12.09 %), total phenols (2.41 mg GAE/ml) and antioxidants (7.08 mg AAE/ml), were used to obtain extracts from grape seeds. The predicted values matched well with the experimental values (12.32 % extract yield, 2.45 mg GAE/ml total phenols and 7.08 mg AAE/ml antioxidants) obtained at optimum SFE conditions. The antiradical assay showed that SFE extracts of grape seeds can scavenge more than 85 % of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The grape seeds extracts were also analyzed for hydroxybenzoic acids which included gallic acid (1.21 similar to 3.84 mu g/ml), protocatechuic acid (3.57 similar to 11.78 mu g/ml) and p-hydroxybenzoic acid (206.72 similar to 688.18 mu g/ml).