Cinnamon leaf oil is obtained by steam distillation of cinnamon leaves and the oil yield ranges between 0.5% and 1.8%. More than 47 compounds have been identified from the leaf oil, the most significant being eugenol, which constitutes 65–92% . Cinnamon leaf oil is cheaper than bark oil and is used in the flavor industry, to a lesser extent, to flavor confectionary. It is also used as a source of eugenol for the preparation of synthetic vanillin. Cinnamon oleoresin obtained by solvent extraction is a dark brown extremely concentrated and viscous liquid, closely approximating the total spice flavour and containing 50% or more volatile oil. It is used mainly for flavouring food products such as cakes and confectionary. Ground spice has been replaced by oils and oleoresin in food industry.
Commonly used in the formulation of health and beauty aids, the very distinct scent of cinnamon leaf is less aromatherapeutic and more medicinal than the very familiar, more pleasant cinnamon bark oil. Also the oil of the leaves has antiseptic properties and so is included as a constituent of many toiletry and remedial products like cleansers, oral rinses and topical skin applications.
Leaf oil distillations are normally carried out in large distillation vessels (200–500 kg). Cinnamon leaves are obtained as a by-product of the cinnamon industry. When the shoots are harvested for bark, the leaves and twigs are trimmed in the field. Before distilling the leaf oil, the trimmed leaves are allowed to remain in the field for three to four days. Traditional leaf oil distillation units consist of a wooden still body with a copper goose neck lid. The condensing system is similar to the bark oil-distilling unit. The steam is generated in a separate kettle like external boiler. The condensed distillate is collected in a series of Florentine vessels. Due to the low solubility of leaf oil in water it turns milky white in colour. Oil separated water is kept stored for days before complete separation of oil from the water. Since leaf oil is heavier than water, oil collects at the bottom of the Florentine vessel. Due to oxidation and to reactions with copper or steel vessels, the oil turns usually dark brown in colour. It takes about six to seven hours to distill one batch of leaf, normally a yield of 1.0% oil on dry weight basis is obtained. After months of operation, a dark resinous material is found in condenser tubes. This is removed by burning condenser tubes in open fire. Cinnamon leaf oil is graded according to the eugenol content.
Like many essential oils it has very strong is scent and can be caustic; it must be diluted and used sparingly with caution.