RUE OIL

Chemical properties

Rue is a biennial or perennial herb widespread in arid areas of southern Europe and North Africa. It has sparse leaves with two to three buds and yellow flowers (May to July) with a strong characteristic odor. It grows to 0.5 m (20 in.) in height. Several other varieties of rue are known, including R. bracteosa, R. montana L., and R. calepensis. The parts used are the leaves and fresh blooming plants. Rue has an herbaceous odor (fruity, orange note) and a sharp, burning, acrid taste.

Chemical properties

The oil is obtained by steam distillation of the fresh blossoming plant in 0.5 to 0.8% yields. The oil has a characteristic fatty odor.

Physical properties

The oil is a yellow to yellow-amber liquid. It is soluble in most fixed oils and in mineral oil, but is relatively insoluble in glycerin and propylene glycol. The essence exhibits different physical–chemical constants depending on the growing site.

Occurrence

Found in the plants Ruta montana L., R. gravolens L. and R. hracteosa L. (Fam: Rutaceae).

The Uses of RUE OIL

Rue oil is a flavoring agent that is the natural substance obtained by steam distillation of the fresh blossoming plants of rue, the perennial herb of several species of ruta (ruta montana L., ruta graveolens L., ruta bracteosa L., and ruta calepensis L.). It is used in baked foods and baking mixes (10 ppm); frozen dairy desserts and mixes (10 ppm); soft candy (10 ppm); and other food categories (4 ppm).

Preparation

By steam distillation from the fresh blossoming plants.

Definition

Extractives and their physically modified derivatives. Ruta graveolens, Rutaceae.

Essential oil composition

The main constituent of rue oil is methyl nonyl ketone

Composition

The main constituents include methylnonyl ketone, methylheptyl ketone (ca. 90%), methyl-n-octyl ketone, pinene, l-limonene, cineol and acids. The dried product contains rutin, quercetin, furocoumarins and alkaloids of the quinoline group. The numbers of compounds detected at concentrations above 0.01% (w/w) in the extracts from leaves, flowers, stems and roots of R. graveolens L. were 78, 45, 25 and 24, respectively. 2-Nonanone (8.9%), 2-undecanone (13.4%), chalepensin (13.0%) and geijerene (19.3%) were the main constituents found in the extracts from rue leaves, flowers, stems and roots, respectively.*

Safety Profile

Moderately toxic by ingestion. Askin irritant. Frequent skin contact causes erythema,vesication. Ingestion of large quantities producesepigastric pain, nausea, vomiting, confusion, convulsions,death; may terminate pregnancy. When heated todecompositi