Cactus pear (Opuntia ficus indica) flavour constituents—chiral evaluation (MDGC–MS) and isotope ratio (HRGC–IRMS) analysis

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Abstract

Among the volatiles isolated by solvent extraction from cactus pear fruit (Opuntia ficus indica) and identified by HRGC–MS, selected chiral and achiral constituents were characterized by enantiodifferentiation and 13C/12C isotope ratio analysis, using multidimensional gas chromatography–mass spectrometry (MDGC–MS) and on-line gas chromatography–combustion isotope ratio mass spectrometry (HRGC-C-IRMS), respectively. While the enantiodistributions determined for methyl 2-methylbutanoate (98 : 2%, S : R), methyl 3-hydroxybutanoate (73 : 27%, R : S), 1-phenyl-ethanol (74 : 26%, R : S), linalool (68 : 32%, R : S), γ-nonalactone (65 : 35%, S : R), γ-deca-lactone (79 : 21%, R : S) and γ-dodecalactone (>99% R) can be discussed in relation to data previously provided for these compounds from various plant origins, the δ13C values of −22.0‰, −21.8‰, −19.1‰ and −20.9‰, measured for 1-hexanol, E-2-hexenol, E-2-nonenol and E,Z-2,6-nonadienol, respectively, are clear-cut indicators for their origin from plants with Crassulaceae acid metabolism (CAM), and thus may helpful for authenticity evaluations. Copyright © 2001 John Wiley & Sons, Ltd.

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