The Comparison of Odor Quality of Volatiles in Peel Oils of Four Kinds of Navel Orange

Abstract

To elucidate the difference of aroma quality among four navel oranges which are very closly related species, the odor quality of volatiles in peel oil was studied by the methods of organoleptic and statistics. The essential oil was prepared by simultaneous distillationextraction from four kinds of navel oranges, such as Washington (Citrus sinensis OSBECK, WASHINGTON), Hukumotobeni (C. sinensis OSBECK cv. HUKUMOTOBENI), Ohmishima (C. sinensis OSBECK cv. OHMISHIMA), Shiroyanagi (C. sinensis OSBECK ev. SHIROYANAGI). Then each oil was separated into two fractions of hydrocarbon and oxygenated compound through a silica gel column. The aroma quality of each component in the fraction of oxygenated compounds having a characteristic aroma was determined by GC-profile, and then by sensory evaluation. Octanal, nonanal, linalool, decanal, neral, geranial, dodecanal, and β-sinensal were selected as the important volatiles for the navel aroma. The odor-unit and odor-contribution of each component in the fraction of oxygenated compounds were estimated on the basis of odor threshold and its concentration. The result did not give enough information for the odor quality, but a mutual relationship of 9 components mentioned above was found by factor analysis. To classify their aroma similarities among these four navel oranges, cluster analyses were performed on the basis of the data regarding to similarity by sensory test. Thus obtained classification (dendrogram) indicated that the similarity of odor quality of peel oil agreed well with that of the mixture of 9 compounds mentioned above. Forthermore, it is suggested that the dendrogram can be separated by the odor-contribution of decanal, dodecanal, terpenes and β-sinensal, respectively.