The volatile constituents of the peel of three cultivars of Australian finger lime (Citrus australasica) were
investigated: Alstonville, Judy’s Everbearing and Durham’s Emerald. Both qualitative and quantitative
GC–MS analyses were performed on their peel solvent extract. The results showed that the unique phenotypes
of finger lime are also correlated to unique molecular compositions. Each cultivar revealed a different
chemotype: limonene/sabinene for cv. Alstonville, limonene/citronellal/isomenthone for cv. Judy’s
Everbearing, and limonene/citronellal/ citronellol for cv. Durham’s Emerald. To the best of our knowledge,
these chemotypes have never been reported in any other citrus species. Furthermore, the amounts
of some volatile constituents (c-terpinene, a-pinene, b-pinene, citral), which are generally the major constituents
besides limonene in lime species, were surprisingly low in the three cultivars. Comparative GC–
MS analysis also showed that some volatile molecules tended to be specific to one cultivar and could
therefore be considered as markers. Moreover six molecules were reported for the first time in a citrus
extract and confirmed by synthesis. Heart-cutting enantioselective two-dimensional GC–MS was performed
to determine the enantiomeric distribution of the major chiral constituents. The combined data
on three finger lime cultivars gives evidence of their divergence from other citrus species.