Qualitative traits and peel essential oil profiles of 24 Italian and international lemon varieties

Lemon (Citrus limon L. Burm. f.) is used for fresh consumption because it is rich in several nutraceutical products especially vitamin C. The physicochemical properties and the bioactive compounds of the peel, such as the essential oil, are strictly depended on the genotype. In this context, peel and juice qualitative traits of 24 lemon cultivars were described: 20 varieties of the Italian germplasm, mostly belonging to Femminello (F.) lines, and 4 international varieties were studied. This study which may be considered one of the few examples carried out on a large number of varieties of a single Citrus species, was conducted over two years and the oils collected by hydro-distillation of the flavedo were analyzed by GC-FID and GC-MS. Differences were observed in the oil yields. For an easier comparison the essential oils’ component were subdivided in five classes: monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpene hydrocarbons, oxygenated sesquiterpenes and others (not terpenoidic compounds). Among the monoterpene hydrocarbons, in all the cultivars the most abundant compounds were limonene, followed by β-pinene and γ-terpinene. In particular, Monachello showed the highest content of monoterpene hydrocarbons, while the lowest value was observed in F. Carrubaro, Fino and Akragas. Femminello lines are interesting cultivars for qualitative traits of the juice (organic acids and vitamin C) and for the highest content of volatile compounds in the peel, such as limonene, myrcene, β-pinene, α-pinene, γ-terpinene and sabinene. Significant differences in morphological and physicochemical traits were observed: fruits of Lemox, F. Adamo and F. Scandurra showed to be seedless, while high acidity content was observed in F. 2Kr, which also showed the highest vitamin C content.