Simon Muhoho Njoroge

Volatile Constituents of Mandarin (Citrus reticulata Blanco) Peel Oil from Burundi

Abstract The essential oil constituents of mandarin (Citrus reticulata Blanco) grown in Burundi were extracted by cold-pressing method and analyzed by GC and GC/MS. Fifty-eight constituents, amounting to 97.2% of the total volatiles were identifed. Monoterpene hydrocarbons accounted for the most abundant chemical group (94.7%). Limonene was the most prominent constituent (84.8%), followed by γ-terpinene (5.4%), myrcene (2.2%) and α-pinene (1.1%). Sesquiterpene hydrocarbons accounted for a minor quantity (0.2%), where germacrene D and valencene were the main constituents. Oxygenated compounds of various chemical groups constituted 2.3%. Aliphatic aldehydes (0.7%) and terpene alcohols (0.7%) were the major chemical groups. The main constituents were linalool (0.7%), octanal (0.5%) and decanal (0.2%). Octyl acetate, α-sinensal, decanol and perillaldehyde occurred at 0.1% levels. Thymol, α-sinensal, methyl thymol, and the acetate esters, bornyl, α-terpinyl, geranyl, citronellyl and decyl acetates were detected, each at < 0.05%.

Analytical Discrimination of the Cold-Pressed Oils of Mandarins and their Hybrids

Abstract Volatile compositions of the cold-pressed peel oils of a Satsuma mandarin cultivar, from Japan, and four other cultivars of mandarin hybrids such as Temple, Orlando, Kara and Minneola obtained from Ethiopia and Kenya were analyzed by capillary GC and GC/MS, without prior separation. Satsuma mandarin and Temple were characterized by high concentrations of (E,E)-α-farnesene and linalool, respectively. The enantiomeric distribution of α-pinene, β-pinene, sabinene, limonene, linalool, citronellal and α-terpineol was studied by simple and reliable enantioselective GC methods involving either a chiral capillary column or an on-line coupling of non-chiral and chiral capillary columns. The (+)-enantiomers of most of the components in all of the analyzed oils were present in excess, except for linalool and citronellal in the oils of Satsuma mandarin and Temple, respectively. Cold-pressed oils of Satsuma mandarin were found to contain about 75% enantiomeric excess of (3R)-(-)-linalool instead of (3S)-(+)-linalool excess, as was found in the oils of other mandarin cultivars and hybrids.

Essential Oil Components of Common Mandarins (Citrus reticulata Blanco) from Uganda

Abstract The aroma components of cold-pressed peel essential oils of common mandarins (Citrus reticulate Blanco) grown in Jinja and Mbarara regions of Uganda were determined by capillary GC and GC-MS. A total of 43 components qualitatively similar in the oils from the two origins were identified. In the respective oils, limonene (85.9 and 86.9 %), y-terpinene (6.0 and 5.4 %), myrcene (2.2 and 2.5 %), a-pinene (1.1 and 1.2 %), linalool (1.0 and 0.7 %), ß-pinene (0.3 and 0.5 %), terpinolene (0.3 %), sabinene (0.3 and 0.4 %) and octanal (0.2 and 0.4 %) were the major components.

Chemical composition of peel essential oils of sweet oranges (Citrus sinensis) from Uganda and Rwanda.

Abstract The chemical composition of cold-pressed peel essential oils of common sweet oranges (Citrus sinensis [L.] Osbeck) from Uganda and Rwanda were analyzed by GC and GC-MS and a total of 51 and 55 volatile chemical components were identified respectively. The major chemical groups were monoterpene hydrocarbons (94.4 and 97.3 %), terpene alcohols (1.4 and 1.0 %), aliphatic aldehydes (1.6 and 0.8 %) and terpene aldehydes (1.4 % and trace). The main compounds were limonene; 87.9 and 92.5 %, myrcene; 2.4 and 2.0 %, α-pinene; 0.5 and 2.4 %, linalool; 1.2 and 0.9 %, octanal; 1.3 and 0.6 % and decanal, 0.2 %. Some of the compounds present in the Ugandan oil, including iso-amyl acetate, iso-safrole, iso-amyl isovalerate, (E)-sabinene hydrate and methyl caprate were absent in Rwandan oil. The Rwanda Citrus oil contains methyl isobutyrate, α-copaene, myrcenol, neryl acetate, geranyl propionate and perilly alcohol which were not detected in Uganda Citrus oil.

Preparation of Citrus Essential Oils: Effects of Silica Gel Treatment on Volatile Composition of Yuzu (Citrus junos) Cold-pressed Peel Oil

Abstract The effects of silica gel, a substance commonly used for fractionation of essential oils during preparation, were investigated on cold-pressed peel oil of yuzu (Citrus junos Sieb. ex Tanaka), a sour Citrus fruit. The silica gel treatment was performed for 24 h at 20°C, 5°C and −2°C. The volatile components were determined using GC and GC-MS. Important compositional changes occurred at 20°C and 5°C and minimally or virtually absent at −21°C. The notably decreased groups were monoterpene hydrocarbons (from 95.7 to 75.2%), sesquiterpene hydrocarbons (from 2.1 to 1.0%) and monoterpene alcohols (from 2.2 to 1.7%). The main decreases were of limonene, phellandrene, y-terpinene, terpinolene, ß-elemene, caryophyllene, trans-ß-farnesene, germacrene D and bicyclogermacrene. Increases of p-cymene, aromadendrene, allo-aromadendrene, cadinene, trans-sabinene hydrate and α-terpineol occurred. Artifact compounds including ß-copaene, d-camphor, viridiflorol and spathulenol were formed. Use of silica gel for preparative treatment of complex Citrus oils could cause alteration of the original composition. The results could be applicable for quality control at the perfume or Citrus juice factory.