Solid phase microextraction (SPME) of orange juice flavor: odor representativeness by direct gas chromatography olfactometry (D-GC-O)

The sensorial quality of solid phase microextraction (SPME) flavor extracts from orange juice was measured by direct gas chromatogrphy-olfactometry (D-GC-O), a novel instrumental tool for evaluating odors from headspace extracts. In general, odor impressions emerging from SPME extracts poorly resembled that of the original orange juice. In an attempt to improve the sensorial quality of extracts, sample equilibration and exposure times were varied on Carboxen/polydimethylsiloxane (CAR/PDMS) and divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) SPME fibers. Best sensorial results were obtained with the DVB/CAR/PDMS fiber exposed for the shortest time; a trained panel of eight assessors judged its odor as the most representative of the reference orange juice. The analysis of odor active compounds by classical GC-O accounted for odor characteristics revealed by D-GC-O. A principal component analysis (PCA) was applied on SPME and headspace extracts using flavor recoveries as variables. Interestingly, PCA discriminated samples according to their odor representations described by D-GC-O analysis. This paper provides the first comprehensive methodology to "smell" SPME extracts and "evaluate" their sensorial quality. This method will enable future investigations to further improve SPME performance.