Chemical and biological evaluation of deterpenated orange and mandarin oils

Abstract: Orange (Citrus sinensis) and mandarin (Citrus reteculata) peels were used to extract their essential oils by cold pressing method. The chemical composition of both oils were identified and determined by GC/MS. Limonene (89.65%) in orange and (65.57%) in mandarin, is a main component of monoterpenes, followed by γ-terpienene (23.07%) in mandarin. Octanal (1.47%) in orange oil and linalool (1.5%) in mandarin oil are abundant oxygenated component determined. Deterpenation of both oils was applied using three different techniques to remove hydrocarbon monoterpenes and thus, increased oxygenated components, alcohols, aldehydes, esters and oxides relatively. Preparative silica gel adsorption chromatography at two ratios (1:7.5 and 1:15 oil to silica) was used for removing terpenes from orange and mandarin oils. The higher level of oxygenated components in deterpenated oil, the lower percentage of oil recovery. Concentration by controlled vacuum distillation techniques, 10 mm Hg and 62 ºC, was applied to produce folded orange oils (5F.O.O and 10F.O.O) and folded mandarin oil (5F.M.O).The higher fold number the lower the monoterpenes content. Limonene recorded 67.88% in (10F.O.O) and 52.95% in (5F.M.O). γ–terpinene as monoterpene did not affect by distillation of mandarin oil. Alcohols increased and recorded 15.67% while, aldehydes represented 10.67% in ten fold orange oils. The main esters as methyl N-methyl anthranilate and geranyl acetate increased in (5F.M.O) than that found in original mandarin oil. The deterpenation of orange oil by diluted ethyl alcohol at 70% (1:5) and 80% (1:5) could be considered as the most effective concentration in comparison with the other concentrates for obtaining deterpenated oils containing the highest amount of aroma oxygenated compounds. Stored folded oils characterized by decrement in limonene, lost in aldehyde aroma components and increased in oxidation products such as cis-p-mentha 2,1 dienol and trans carveol. Losing limonene during storage in original oils led to increase in specific gravity, refractive index, evaporation residue and acid value. The improvement of antioxidant capacity of concentrates (5F.O.O, 10F.O.O and 5F.M.O) and deterpenated fractions (F3 and F5) than their original oils were related with increasing minor components by deterpenation such as carvacrol, geraniol, α-terpineol and linalool or related with other terpene component γ-terpenene in (5F.M.O). Deterpenated and concenterated orange oils were more effective on Bacillus subtilis and Staphylococcus aureus than original oils because the increment of oxygenated monoterpenes by deterpenation as well as synergistic interaction of other constituents. The efficiency of folded oils in hypocholestrolimic rats did not affected by decreasing of limonene by deterpenation. The original and folded oils were used as a flavoring agent in the formulation of chewing gum.
Publication year 2015
Country Egypt
External authors (outside ARC)