Essential oil constituents of three varieties of Kenyan sweet oranges (Citrus sinensis)

The volatile components of peel essential oils of Salustiana (Citrus sinensis Osbeck forma Salustiana), Valencia (C. sinensis Osbeck forma Valencia) and Washington navel (C. sinensis Osbeck forma Washington navel) sweet oranges grown in Kenya were isolated by cold-pressing and determined by GC and GC-MS. A total of 56 components were identified in Salustiana, 73 in Valencia and 72 in Washington navel peel oils. The identified components amounted to 98.7, 97.8 and 97.4% of the total volatiles of each oil, respectively. Monoterpene hydrocarbons largely dominated in the volatile fraction of the Salustiana (96.9%), Valencia (94.5%) and Washington navel (92.7%) oils. In each oil, limonene, alpha-pinene, sabinene and alpha-terpinene were the major compounds. Sesquiterpene hydrocarbons amounted to 0.1% of the total volatiles of Valencia and Washington navel oils, where (E,E)-alpha-farnesene was the main compound. The total oxygenated compounds amounted to 1.7, 3.4 and 4.5% of the Salustiana, Valencia and Washington navel volatiles. Linalool, decanal, (Z)-carvone, (Z)-carveol, (E)-carveol, nootkatone and sabina ketone were the main components. The three sweet orange varieties could be differentiated by the unique presence of alpha-phellandrene and gamma-terpinene in Salustiana, beta-phellandrene, (Z)-nerolidol, aromadendrene in Valencia and p-cymene, beta-sinensal and dodecanoic acid in Washington navel oils. Copyright (C) 2004 John Wiley Sons, Ltd.