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One to two hundred kilograms of yellow flowers in a wood fired still on the island of Anjouan. More than ten hours of steam passing through. Receivers set one after another, and five names for the same batch of flowers: Extra, I, II, III, complete.

One Batch, Many Hours

Ylang ylang flowers, Cananga odorata forma genuina, are long, narrow, ribbon like and yellow. In the Comoros they are picked by hand early in the day and distilled the same day. Each tree gives about a kilogram of flowers per picking round; a still takes 100 to 200 kilograms.

The Union of the Comoros, above all the island of Anjouan, remains the world's largest source of ylang ylang. According to Pierre William Johnson's value chain study of 2023, the Comoros produce 40 to 70 tonnes of oil a year out of roughly 100 tonnes worldwide; Anjouan alone accounts for about 70 percent of the national output. In 2022 between 100 and 150 stills were active on the island, most of them burning wood.

A ylang ylang distillation runs a very long time; sources give from about ten to more than twenty hours. What is unusual is not the length but how the oil is collected. The distillate is not pooled in a single vessel. It is collected in successive receivers, by time and by density. Each receiver is a fraction, and each fraction is sold as an oil of its own.

This is fractional distillation in its simplest form: no column, no vacuum, only a clock and several receivers.

Light Molecules Come First

An essential oil is a mixture of tens to hundreds of molecules, each with its own boiling point. In the still, steam carries the most volatile molecules first. Heavier ones need many hours of steam before they are fully out. Time in the still therefore decides which molecules appear in which receiver.

With ylang ylang, the first portion is rich in esters and aromatic ethers: benzyl acetate, p cresyl methyl ether, methyl benzoate, together with linalool. These are strong smelling molecules carrying the floral and sweet side of the flower. Later portions become richer in sesquiterpenes such as beta caryophyllene, germacrene D and alpha farnesene, heavier molecules that smell woodier and spicier, less floral.

One detail is easy to misread. The first portion comes over first because its molecules are more volatile, yet the early oil has the higher density. Under ISO 3063, at 20 °C Extra has a density of about 0.965 to 0.975, grade I about 0.960, grade II about 0.955, and grade III the lowest. The aromatic esters and ethers are denser than the sesquiterpene hydrocarbons, even though they boil earlier. Light in volatility and light in density are two different things.

Density therefore becomes a sorting tool. The distiller measures the density of the distillate to know when to switch to the next receiver, and the standard uses those same values, along with refractive index, optical rotation and ester value, to define each grade.

Extra, I, II, III and Complete

The trade calls the fractions Extra, I, II and III, in French premières, secondes, troisièmes. Extra is usually the portion collected in roughly the first one to two hours. It is the most expensive grade, with the deepest and strongest floral scent, used in fine perfumery. Some sources split off an Extra Superior, or Extra S, with a density of 0.980 or above. The library's glossary records these grades.

Extra is rich in strong smelling molecules: p cresyl methyl ether 5 to 16 percent, methyl benzoate 4 to 9 percent, linalool 7 to 24 percent, benzyl acetate 5.5 to 17.5 percent, geranyl acetate 2.5 to 14 percent. Grade I is still premium. Grade II is used in commercial perfumery. Grade III is the final portion, woodier and cheapest. According to the library, only Extra and grade I are usually used in fine perfumery.

Complete is the most confusing name. Some sources use it for oil distilled in one run without fractions. Others use it for a blend reassembled from the fractions. The word complete on a label does not say which; the supplier's technical sheet is where to check.

On safety, the Lê Mai library lists a maximum of 0.8 percent on skin for the Extra, I and II grades; complete may be higher. Ylang ylang also contains several allergens that must be labelled in the EU, such as linalool, geraniol, benzyl benzoate and benzyl salicylate. Different fractions carry these in different proportions, so each grade needs its own composition sheet.

Ylang Ylang and Cananga

The same species, another form, another oil. Cananga comes from Cananga odorata forma macrophylla, is distilled mainly in Java, Indonesia, and has its own standard, ISO 3523:2002. Unlike ylang ylang, cananga oil is usually sold as a single oil, without the Extra, I, II, III grading.

Cananga's composition leans firmly toward the late fractions of ylang ylang. Beta caryophyllene about 38 percent, alpha caryophyllene about 9 percent, germacrene D about 8 percent. It smells greener, woodier, less sweet. If Extra is the flower of the flower, cananga is a rougher sibling standing near grade III.

Because it costs less, cananga is used in perfumery as a more economical alternative to ylang ylang in some applications. Also because it costs less, it is one of the materials often found when ylang ylang oil is cut, along with synthetic linalool and geranyl acetate, gurjun balsam, benzyl benzoate and propylene glycol. In the Comoros, the addition of synthetic benzyl acetate to oil has been reported for about fifteen years.

Gas chromatography with mass spectrometry, reading the ratio of linalool and alpha farnesene, is the way to check. In 2020 the Comoros set up a national interprofessional body for ylang ylang; since March 2022 distillers and collectors must register.

Fractions in Other Oils

Ylang ylang is fractionated within the first distillation. The second way is to take a finished oil and redistil it through a fractionating column, usually under vacuum. Lower pressure lowers boiling points, so the oil is separated at lower temperature with less heat damage. The operator divides the distillate into at least three parts: heads, the lightest molecules, usually monoterpene hydrocarbons; the heart, or coeur; and tails with the residue, the heavy molecules, colour bodies and non volatiles.

Patchouli is the familiar example. Crude patchouli oil is dark, with earthy and musty edges. Redistilled under vacuum, the light heads and the dark residue are removed; the heart is richer in patchoulol and paler. One study of molecular distillation of patchouli oil reached about 62 percent patchoulol in the product. Suppliers sell this as patchouli heart, with the patchoulol content stated on the technical sheet.

ISO 9235 uses mint oil as its example of a rectified essential oil, an oil that has undergone fractional distillation to change the content of certain compounds or its colour. For birch tar and cade, rectification is also an IFRA condition for fragrance use, because the step lowers polycyclic aromatic hydrocarbons. For bergamot, vacuum distillation removes furocoumarins, giving the FCF grade.

When the aim is to remove light terpenes so the oil becomes more concentrated, the product is a terpeneless or folded oil, the subject of rectified, folded. When the cut is made very narrow around the boiling point of one molecule, the product is an isolate.

Reading the Label

The small words on an essential oil label often record time in the still. Extra, I, II, III and complete belong to ylang ylang. Heart, coeur or fraction indicate a heart cut. MD usually indicates molecular distillation. Rectified indicates an oil redistilled to change its composition or colour.

A bottle labelled ylang ylang with no grade deserves a question. It may be complete in the sense of a single run, it may be a blend of fractions, it may be grade III at the price of grade I. The smell gives a hint: Extra opens with a sweet, strong floral note; grade III opens with wood and spice, the flower arriving late and faint.

Origin leaves a mark too. A comparison of Comorian and Malagasy oils found more cinnamyl acetate, benzyl salicylate and farnesyl acetate in the Comorian oils. The Comoros and Réunion region was once known collectively as Bourbon, and the name still appears on the labels of some oils from these waters.

Lê Mai's Blend #900 Ylang Ylang Amber takes ylang ylang as its floral note. Behind a short name on a label lies a decision about which hours of the still were chosen.

One still of flowers, five names.

Time divides the flower into parts on its own.

The label only records which hours were kept.