Compositional Changes in Yuzu (Citrus junos) Steam-Distilled Oil and Effects of Antioxidants on Oil Quality during Storage

Changes in 44 compounds of yuzu (Citrus junos Sieb. ex Tanaka) steam-distilled peel oil (SDO) and possible artifacts that accrue during storage at 25 degrees C were investigated after 1, 2, 3, 4, 8 and 12 weeks. Changes in SDO composition during storage took place more rapidly than in cold-pressed oil. Total monoterpene hydrocarbons decreased markedly, with major losses of limonene and gamma-terpinene and notable increases in p-cymene, as well as alcohols. Bicyclogermacrene, the main sesquiterpene hydrocarbon of the fresh oil, practically disappeared. (-)-Spathulenol, the main artifact, was converted from bicyclo-germacrene. Antioxidants such as alpha-tocopherol, beta-carotene and 2,6-di-tert-butyl-4-hydroxytoluene (BHT) slowed the formation of oxidation products, such as p-cymene, (-)-spathulenol by inhibiting the formation of oxidative products. This suggests that the antioxidants can be used to maintain yuzu oil quality.