Determination of the oil content of seeds by focused microwave-assisted soxhlet extraction

Soybean, rape and sunflower lipids have been extracted with a focused micro wave-assisted Soxhlet extractor The main factors affecting extraction effic iency, namely microwave irradiation power, number of cycles and microwave i rradiation time were optimised by means of a central composite design based on a two-level-three-factor factorial design. A study of the influence of particle size on the extraction procedure was also performed. The results o btained were compared with those obtained by use of an ISO method using a c onventional Soxhlet extractor Quantitative results for lipid content based on gravimetric determinations and qualitative results based on analysis of fatty acid methyl esters and polymeric compounds were similar to those obta ined by Soxhlet extraction with hexane. Substantial reduction of sample man ipulation, analysis time and solvent wastage is achieved by use of the prop osed method.