In our discussion of cinnamon, we noted that the flavor of cinnamon is in what is called the “essential oil” of the bark. The concentration of the essential oil is the highest in Saigon cassia cinnamon, ranging as high as 6%. The main chemical in the oil is cinnamic aldehyde.

This raises the question as to what an essential oil is. Essential oils are part of a plant’s biological make-up. They are tiny droplets which are stored in glands of plants. From the glands, they are spread over the exterior surface of the plant. The oil covers the surface of limbs and leaves, and then evaporates, filling the air with perfume. You have undoubtedly noticed that when you brush your hand across herbs plants, such as thyme or basil, your fingers will smell like the herb. That is because the essential oil has come off on your hand.

There is some uncertainty as to the function of essential oils. It is believed that they protect the plant against parasites and animals, and also seal the surface of tree trunks to prevent loss of sap. The oils also attract insects that fertilize the plants. Some believe the oils are involved in plant metabolism; some believe they are simply waste products. Regardless, it is the oils that give plants their characteristic odor and taste.

Essential oils have been used for centuries going back to ancient India, Persia, and Egypt. Originally they were used medicinally. Oil of cinnamon was used, for instance, to aid in digestion; it still is. Essential oils continue to be used in medicine, but are more commonly used (1) to give odors to perfumes, soaps, detergents, animal feeds, insecticides, and paints, and (2) to give flavors to baked goods, candies, meat, pickles, and soft drinks.

The first records of essential oils being isolated from plants come from ancient India, Persia, and Egypt. There was an extensive trade in such oils in ancient Greece and Rome. In the Middle Ages, Europeans used distillation to obtain the essential oils from the spices of Asia, spices such as cardamom, sage, cinnamon, and nutmeg. In the 19th century the essential oils of four American plants were isolated: sassafras, wormwood, wintergreen, and sweet birch.

At first the oils were obtained by laying the leaves of plants on a pure cold fat, such as a mixture of tallow and lard. The oils impregnated the fat, called “pomade,” which was then sold. Distillation was used by the Arabs. Oils were obtained by placing the crushed leaves or bark in or over water which was boiled. The steam passing through the plant parts picked up the oil; the steam was cooled and the oil then separated from it. Solvents were also used to obtain the oil, particularly ethyl alcohol, which was first distilled from fermented sugar by the Arabs. Citrus oils were obtained by squeezing the peel in presses, and then centrifuging the juice to separate the oil from the water and pulp, much like extra virgin olive oil. We sell lemon, lime, and orange oils under the Boyajian label.

Essential plant oils can have just a few chemical components which predominate. For instance, cassia cinnamon oil is 95% cinnamic aldehyde;wintergreen is 98% methyl salicylate. However most oils have a few dozen to several hundred components. Trace components are very important, giving each natural oil a characteristic odor and flavor. An artifically derived oil lacks the full range of chemicals in a natural oil and thus have a flat “chemical” odor. This is the same problem with artificial vanilla, as I explained in our vanilla discussion.