Optimization of solvent free microwave extraction of natural antioxidant from wood waste

Solvent free microwave extraction (sfme) of oil from maritime pine wood waste and its antioxidant activity were investigated and compared to classical hydrodistillation (hd) method (clevenger apparatus). a central composite design combined with response surface methodology was applied to evaluate the simultaneous influences of irradiation power,irradiation time and moisture content before sfme. a maximal extraction yield of 0.43% (g/100 g dry wood waste) was achieved under optimal extraction time of 43 min and an irradiation power of 668 w compared 0.28% obtained for the conventional method (hd). the results also showed that the three independent variables had a statistical significant effect on the considered response as well their quadratic effects. gas chromatography coupled to mass spectrometry (gc-ms) analysis showed that sfme extract is richer in oxygenated compounds (~58.5%) compared to hd extract (34.1%). the comparison of total phenolic compounds (tpc) showed that under optimized condition of sfme procedure,the amount of tpc was 74.6 mg gae/g extract,largely higher than that obtained for hd extraction (51.2 mg gae/g extract) suggesting that sfme represents an interesting alternative technology for production of recoverable oil from waste issued from maritime pine wood waste. moreover,the antioxidant activity assessed by 2,2-diphenyl-1-picrylhdrazyl (dpph) test showed that the concentration that inhibit 50 of dpph radical was lower for sfme (15.4 μg/ml) compared to hd (123 μg/ml and to a synthetic antioxidant (bht) (24μg/ml). © 2017,university of mohammed premier oujda morocco.