Germacrenes in Citrus Peel Oils

The germacrene composition of various citrus peel oils was investigated. Detection and quantification of the thermally sensitive germacrenes A and C was achieved by employing extremely gentle GC conditions with 100°C maximum in injector and GC-oven. Germacrene A was found in all analyzed citrus oils with values from trace level to 0.46% of the volatiles, depending on variety and provenance. Germacrene C was identified in the peel oils of bergamot, bitter orange, lime, Minneola, Ortanique tangor, pummelo, Sweetie, tangerine and Yuzu with values of 0.01–0.59%. In this context, germacrene C always occurred accompanied by germacrene B. Germacrene D was present in all citrus peel oils, with the exception of lemon, whereas bicyclogermacrene was a constituent of all examined citrus oils, except for lime. Distilled lime oil as acidic steam distillate possesses a special position, as it contained only germacrene B.