Determination of aldehydes as pentafluorobenzyl derivatives in grape pomace distillates by HS-SPME-GC/MS

This work describes an analytic method that quantifies aldehydes in grape pomace distillates (Orujo). Diluted samples were derivatised with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine and then microextracted with a solid phase (SPME) for analysis by GC-MS. Twenty compounds, among them, short chain aldehydes having pungent notes (propanal, butanal, and Strecker aldehydes) and long chain aldehydes characterised by fatty odours were studied. The extraction was optimised and the method showed a good linearity over the ranges tested, good detection limits (0.7 ng/L < LOD <20 ng/L), as well as an excellent repeatability (RSD < 10%). The optimised method was applied to different grape pomace distillates obtained by system of steam distillation with demetilant column (also known as a "vertical metho extractor"). The use of the column has caused dramatic changes of the quality profile of the distillate, associated to rancid and piquant smell that can be amended with this new process. (C) 2011 Elsevier Ltd. All rights reserved.