A multivariate study of the performance of a microwave-assisted Soxhlet extractor for olive seeds

The operating variables affecting the performance of a conventional Soxhlet extractor modified for application of focused microwaves on the sample chamber has been evaluated. An experimental approach based on a central composite design (CCD) and olive seed samples was used. The new variables introduced by means of the modification are irradiation power and time, and cycle number, which were chosen for evaluation. Statistical treatment of the results provided by the CCD revealed that the selected parameters were all significant; also, their optimum values were used in order to assess the predictive ability of the model relative to both the central points of the design and the conventional Soxhlet. The extraction time is reduced from 8 h to 20-25 min; also, the proposed method is less-labour intensive (the official method entails halting the extraction twice to grind the sample). Another achievement of the proposed method is that 75-80% of the extractant is reclaimed which makes it a nearly clean approach. (C) 1999 Elsevier Science B.V. All rights reserved.