Determination of flavor constituents in particular types of flour and derived pasta by heart-cutting multidimensional gas chromatography coupled with mass spectrometry and multiple headspace solid-phase microextraction

A Multiple Headspace Solid-Phase Microextraction (MHS-SPME) method was optimized for the isolation and quantification of volatile compounds from samples of flour and pasta, obtained from buckwheat and Khorasan wheat. In a second step, SPME extracts were analyzed by means of a Multidimensional Gas Chromatographic (MDGC) system, operated in both "stand-by" and "heart-cutting" modes. The first dimension was equipped with a non polar column and an FID detector; the second dimension was provided with a modified beta-cyclodextrin stationary phase and mass spectrometric detector. Such instrumental apparatus, under accurately optimized conditions, allowed to obtain detailed fingerprints with the definition of markers of quality and traceability among the various samples investigated. Some volatiles (i.e. 3,4-hexanedione, hexanal, 1-octen-3-ol, 2-pentylfuran, germacrene D) were commonly present in all the samples, some others (i.e. undecanal, gamma-nonalactone, neryl acetone) only in one cereal species. In addition, the determination of enantiomeric ratios of optically active volatiles was successfully carried out, with the separation of 14 enantiomer pairs. Fifty % of chiral components showed an almost racemic composition, while the remaining pairs evidenced a predominance of the levorotatory enantiomer. Quantification of key volatiles was performed through MHS-SPME, a calibration methodology specifically developed for headspace analysis, which allowed to determine 3,4-hexanedione (2.2.10(-3) g/kg), 2-pentylfuran (3.4.10(-3) g/kg) and germacrene D (4.2.10(-3) g/kg), as major compounds