Optimization of supercritical carbon dioxide extraction of antioxidants from roasted wheat germ based on yield, total phenolic and tocopherol contents, and antioxidant activities of the extracts

Effects of pressure (148-602 bar), temperature (40-60 degrees C) and time (10-60 min) on antioxidant (phenolics and tocopherols) contents and antioxiclant activities of supercritical carbon dioxide (SC-CO2) extracts of roasted wheat germ were determined, using central composite rotatable design. The dependent variables were yield (%), total phenolic contents (TPC, mg gallic acid equivalent (GAE)/g extract), total tocopherol contents (TTC, mg tocopherol/g extract) and antioxidant activities (AA, mg scavenged 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH,)/g extract) of the extracts. The antioxiclant purity of the extracts (TPC, TTC and AA) were high at extraction conditions where the extraction yield was low (148-165 bar, 40-60 degrees C and 10 min). The optimum extraction conditions found by maximizing all the dependent variables were 336 bar, 58 degrees C and 10 min, where 5.3% yield, 6 mg GAE phenolics/g extract, 6.7 mg tocopherol/g extract and 57.3 mg scavenged DPPH./g extract was predicted. The tocopherol yield under these conditions corresponded to almost complete recovery. (C) 2008 Elsevier B.V. All rights reserved.