On-line gas chromatography combustion/pyrolysis isotope ratio mass spectrometry (HRGC-C/P-IRMS) of major volatiles from pear fruit (Pyrus communis) and pear products

Using extracts obtained by simultaneous distillation extraction (SDE) as well as liquid liquid extraction (LLE) of self-prepared juices from pear fruits ( n = 20) and from commercial pear products (juices, n = 11; brandies, n = 16; baby food, n = 8), on-line capillary gas chromatography–isotope ratio mass spectrometry was employed in the combustion (C) and the pyrolysis (P) modes (HRGC-C/P-IRMS) to determine the δ 13 C V-PDB and δ 2 H V-SMOW values of major pear flavour constituents. In addition to butyl acetate 1 , 1-butanol 2 , hexyl acetate 3 , 1-hexanol 4 , as well as the ‘pear esters’ methyl E , Z -2,4-decadienoate 5 , ethyl E , Z -2,4-decadienaote 6 , and ethyl E , E -2,4-decadienoate 7 , each originating from the fruit, the δ 13 C VPDB and δ 2 H V-SMOW data of commercial synthetic and “natural” (biotechnologically derived) 1 – 7 were determined.