Essential oils of Kenyan <i>Citrus fruits</i>: volatile components of two varieties of mandarins (<i>Citrus reticulata</i>) and a tangelo (<i>C. paradisi</i> × <i>C. tangerina</i>)

Abstract

Abstract The volatile flavour components of essential oils in peel of kara and sabine mandarins ( Citrus reticulata ) and minneola tangelo, a hybrid between Duncan grapefruit ( C. paradisi Macfadyen) and Dancy tangerine ( C. tangerina Tanaka) grown in Kenya were extracted by cold‐pressing and analyzed by GC and GC‐MS. A total of 48, 72 and 56 components amounting to 99.4, 99.8 and 99.8% were identified in each oil, respectively. Monoterpene hydrocarbons constituted 98.1, 96.9 and 96.7% in the respective oils. The major compounds were limonene (87.1–90.7%), γ ‐terpinene (1.5–2.9%), terpinolene (1.4–2.2%) and myrcene (1.5–1.8%). α− Terpinene was prominent in sabine oil (3.4%) but absent from kara and minneola oils. β ‐Caryophyllene, α ‐cubebene and ( E , E )‐ α ‐farnesene amounting to minor percentages (0.2–0.3%) were the notable sesquiterpenes in each oil. Oxygenated compounds constituted 1.1, 2.6 and 2.8% of the kara, sabine and minneola oils, respectively. Carbonyl compounds (0.6–1.3%) and alcohols (0.3–1.3%) were the major groups, whereas linalool (0.2–0.6%), decanal (0.2–0.3%) and octanal (0.2–0.3%) were the prominent compounds. β ‐Sinensal was present in each oil at trace quantities. α ‐Sinensal and nootkatone were found only in sabine oil. The oils exhibited complex and variable compositions of alcohols, aldehydes and ketones. ( E )‐ p ‐Mentha‐2,8‐dienol, p ‐mentha‐1(7), 8(10)‐dien‐9‐ol, p ‐menth‐8‐en‐1‐ol and ( E )‐pinocarvyl acetate found among the oils have not been previously reported in mandarin peel oils. Copyright © 2004 John Wiley &amp; Sons, Ltd.