The physicochemical indices and the qualitative and quantitative composition of the volatile fraction and the oxygenated heterocyclic fraction of cold-pressed Key lime oil (types A and B) and Persian lime oil are reported. The volatile fraction of Persian lime oil is characterized by a higher content of limonene, γ-terpinene, esters, and monoterpene aldehydes and a lower content of -pinene + sabinene, sesquiterpenes, and aliphatic aldehydes than Key lime oils. Oxypeucedanin was not detected in Key lime oil type A, while it is present in Key lime oil type B and Persian lime oil. This is probably due to the extraction technology used for Key lime oil type A, which allows the essential oil to come into contact with the juice. Under these conditions, the epoxy ring of oxypeucedanin is opened by hydrolysis to form oxypeucedanin hydrate.

The authors report the results of a study made on 488 samples of genuine lemon oil obtained by industrial processing during the 1983/84 season. The lemons, which came from Sicilian lemon‐growing areas, were processed using ‘pelatrice’ or ‘sfumatrice’ extractors. Gas chromatography of all samples was effected using capillary columns. The ‘citral’ content and ‘CD’‐values were also determined. From the gas chromatography of the oils and the fractions obtained by separation on neutral alumina columns, it has been possible to identify 34 components, which correspond to about 99.3% of the volatile fraction of the essential oil, and to establish the class to which numerous other components belong. The quantitative data obtained by gas chromatography are expressed separately, as the average of the values for each month, for the ‘pelatrice’ and ‘sfumatrice’ extracted oils. The quantitative variations found in the various classes of substances and in the principal components present in the lemon essential oils during the whole season of production are commented upon and the fundamental quantitative differences between ‘pelatrice’ and ‘sfumatrice’ extracted oils are illustrated. The results obtained are compared to those which resulted from an analogous study effected during the 1982/83 citrus production season, and confirm that the composition of lemon essential oil undergoes cyclic variations lasting one year.

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