by Mandy Aftel
Expression, in which fruits with skins rich in essential oils, such as the citruses—lemon, lime, orange, grapefruit, and bergamot—are pressed to render the oil, is the oldest and simplest method of deriving natural essences from plants. Originally this was done by hand, and the oil was collected in a sponge. Now it is done by machines that wash the rind and separate it from the fruit and inner white pith. The peel is squeezed through giant rollers, and the oils produced are separated from the juices, waxes, and other substances by whirling the mixture at high speed in a centrifuge.
Expression, detail from Egyptian tomb painting
Alchemists practiced the art of distillation and developed it to a fairly sophisticated level. Typically, they placed the prima materia, a raw botanical mass, in water at the bottom of a still. When the fire under the still brought the water to a boil, vapor rose into a cooler chamber above, where it condensed into a liquid essence. One can imagine how this process heightened the early alchemists’ sense of mystery and power when they saw the great reduction of the botanical material to its essence: a metric ton of leaves yields approximately twenty pounds of essential oil.
Press for rendering essential oils
Distillation made possible two major innovations in perfumery. First, it allowed the extraction of high-quality essential oils from a much wider variety of plants. (Steam distillation does not, however, yield high-quality oils from citrus-fruit rinds, because heat has a deleterious effect on their delicate oils. Nor does it successfully extract the fragrance of flowers other than roses.) Distillation also allowed the manufacture of alcohol of higher concentration than could be obtained by fermentation alone. This highly concentrated alcohol remains the perfumer’s all-purpose diluent and fragrance carrier. To this day, it is used to extract the odoriferous elements from fragrant natural materials and to preserve them, in a true and fresh state, in the form of tinctures and infusions that can be blended to make perfume.
Distillation with water is the method most widely employed for obtaining essential oils today. The method depends on the fact that many substances whose boiling points are far higher than that of water are volatilized if their vapors are mixed with steam. The volatile substance must also be insoluble in water, so that on cooling, it separates from the watery distillate and can be preserved in a relatively pure condition.
In direct distillation, the plant material is in contact with the boiling water. Steam distillation is the more common and gentle method for the extraction of essential oils. Steam is generated in the still (sometimes it is supplied by a separate boiler) and blown through a pipe in the bottom of the still, where the plant material rests on a stack of trays for quick removal after exhaustion.
Distillation does have its limitations. Some of the components that make up the natural perfume of flowers are, chemically speaking, so fragile that they are decomposed by the heat of the operation and spoiled. As the distinguished French scientist Dr. Eugene Charabot, a pioneer in the extraction of fragrance materials, observed, the task of capturing a flower’s perfume is like “capturing the soul of the flower. The flower is something of a coquette, upon whom we have only to bring tribulation when her beauty disappears. She cannot tolerate any harshness, and often the least trouble that affects her, deprives her of her charms.”
Steam distillation
Enfleurage is a method of extracting essences from flowers that is more than a century old. It makes use of the fact that the volatile perfume material of flowers is soluble in fat. Glass plates, each supported in a wooden frame, are coated on both sides with layers of fat. Flower petals are laid on the plates, and the plates are piled on top of one another, so that the volatile products given off are caught by the layers of fat above and below. When all the perfume of the petals has been absorbed by the fat, they are replaced with a fresh supply, and the process is repeated until the fat is saturated with the perfume. This saturated fat is known as a pomade, and it is then dissolved in an alcohol-based solvent in order to obtain the essential oil.
Enfleurage is an intensely sensual process, whose voluptuousness is well captured by Patrick Suskind in the novel Perfume:
The souls of these noblest47 of blossoms [jasmine and tuberose] could not be simply ripped from them, they had to be methodically coaxed away. In a special impregnating room, the flowers were strewn on glass plates smeared with cool oil or wrapped in oil-soaked cloths; there they would die in their sleep. It took three or four days for them to wither and exhale their scent into the adhering oil. Then they were carefully plucked off and new blossoms spread out. This procedure was repeated a good ten, twenty times and it was September before the pomade had drunk its fill and the fragrant oil could be pressed from the cloths … In purity and verisimilitude, the quality of the jasmine paste or the huile antique de tubéreuse won by such a cold enfleurage exceeded that of any other product of the perfumer’s art. Particularly with jasmine, it seemed as if the oiled surface were a mirror-image that radiated the sticky-sweet, erotic scent of the blossom with life-like fidelity.
Enfleurage of jasmine, Grasse
Enfleurage, alas, is no longer commercially viable. It has been replaced by solvent extraction, which has been likened to dry cleaning. Flowers are placed on racks in a hermetically sealed container. A liquid solvent, usually hexane, is circulated over the flowers to dissolve the essential oils. This produces a solid waxy paste called a concrete. The concrete is then repeatedly treated with pure alcohol (ethanol), which dissolves the wax and yields the highly aromatic liquid known as an absolute. This method is also used for extracting resins and balsams and for rendering the animal essences, such as civet, musk, ambergris, and castoreum.
Odorous material comes in many forms and many levels of intensity. In developing one’s palette of natural essences, it is important to understand the variations on a theme—the subtle difference between a jasmine absolute and a jasmine concrete, for example. Even slightly different forms of the same odor have a different value for the perfumer, in terms of technical issues like staying power and also for their own inherent sensual qualities and associations. For example, I like the thickness and substantiality of the pastelike floral concretes; they give the sense of working with a primordial substance. Essential oils are often thin and light in color. I prefer working with the deeply colored and more viscous absolutes; they make me feel more solidly connected to the plant itself.
The following is intended as a general introduction to the family of perfume ingredients; the next few chapters elaborate on these, and the appendix, “Supplies for the Beginning Perfumer,” suggests which materials you will need to get started as a perfumer.
ESSENTIAL OILS
Essential oils are the largest category of odoriferous materials, and the most widely available, thanks to the tremendous popularity of aromatherapy. As mentioned earlier, a few essential oils are still rendered by simple pressing. Most oils, however, are extracted by the process of steam distillation, while a few delicate flower oils that deteriorate quickly under the influence of heat and steam must be extracted with volatile solvents. Rectified essential oils are distilled twice to remove color, water, resinous material, and impurities, but I prefer materials that are the least processed and closest to their natural state. As with food, many delicate and trace elements of the odorous body can be lost through processing.
As we shall see in the following chapters, essential oils are classified according to their volatility (from the Latin volare, “to fly”), or the rapidity with which they vaporize and spread throughout the air. Most essential oils are highly volatile: silver pine, anise, basil, bay, bergamot, bois de rose, cardamom, fir needle, grapefruit, lavender, lime, lemon, and orange peel. Carrot seed, cedarwood, chamomile, cinnamon, and clove are not as volatile, and ambrette seed, angelica root, and cognac still less. Only one plant, the orange tree, yields four distinctly different oils: from the leaves and twigs comes petitgrain; from the flowers we procure neroli and orange flower absolute; and from the rind
of the fruit, essential oil of orange.
Essential oils are often adulterated, and it is important that the company you purchase them from will warrant their purity. To test for the purity of an essential oil, put a drop of it on a piece of white paper. Let it dry at room temperature. If it is pure, the spot will completely evaporate. If the oil is adulterated, a greasy or translucent spot will be left on the paper. Sometimes an old but pure oil will leave a transparent stain around the rim of the spot, which is caused by resin that is formed by the absorption of oxygen and remains dissolved in the oil, but the center should be clear.
RESINS AND BALSAMS
Resins are the viscous solid or semisolid gums derived from trees, such as frankincense and myrrh, or dry lichens growing on the bark of trees, such as oakmoss. They are of great use to the perfumer for their staying power, as we shall see in chapter 3. Resins are soluble in alcohol but not in water.
Balsams are raw, resinous semisolid or viscous materials exuded by trees, usually through incisions in the bark. They often have a cinnamon or vanilla scent. They are almost completely soluble in alcohol, and, like the resins, they help to “fix” a perfume and make it last.
CONCRETES AND ABSOLUTES
Natural flower oils are distilled from fresh flowers by solvent extraction. Because the flowers give off a great deal of waxy material, the process yields a so-called concrete, which is semisolid. Concretes have great staying power, but there’s a softness in their aroma. Although they are not completely soluble in alcohol, they are perfect for making solid perfume. (If they are infused into a liquid perfume, the insoluble dregs need to be strained after the aging process.)
By removing waxes and other solids, a concrete can be rendered into an absolute, a highly concentrated liquid essence that is entirely alcohol-soluble. I have sampled tarragon, nutmeg, fir, ginger, and black and white spruce absolutes, and they are some of the most exquisite and complicated odors I have ever smelled. Absolutes are floral essences at their truest and most concentrated. They are much more lasting than essential oils and have an intensity and fineness to their aroma that are unequaled. Naturally, they are the most expensive perfumery ingredients.
Chinese still for cassia oil
STORAGE
Natural essences are easily damaged by exposure to light and air, and by radical changes in temperature. They should be stored in small, dark glass (not plastic) bottles, with the tops tightly sealed to prevent deterioration of the fragrance. If you live where it is extremely hot and humid, you may consider keeping them in the refrigerator. Always label both the bottle itself and the cap or stopper; it is amazingly easy to put the wrong top on the wrong bottle.
The more often you open a bottle containing a natural essence, the greater the chance of oxidation, which increases the resinifying of the essential oil itself and hastens the staleness of the citrus oils in particular. Try not to open any more often than necessary. If you buy your essential oils in large quantities in order to save money, you should immediately transfer a small amount to a small bottle to preserve the rest. If the first whiff upon opening begins to smell stale or rancid, or you notice that an oil has become thicker or hazy, the essence may have deteriorated.
Most natural essences will keep for many years stored in this fashion. A number of them—jasmine, orris, patchouli, rose, sandalwood, frankincense, rosewood—ripen, growing richer and deeper over the years. Rose and cedarwood may form crystals, but they are not a sign of damage and can be dissolved by the warmth of your hand on the bottle. Citruses, however, deteriorate easily. They should be purchased in small quantities and stored in the refrigerator. After about half a year (or sooner if they begin to smell flat or off), they should be replaced.
HOW TO SMELL
The first step in making perfume is to get to know the repertoire of essences. And the best way to get to know them is to play with them—smelling them, comparing them, combining them, experimenting with them. To smell as a perfumer you have to smell with your imagination—to imagine the essences diluted, to imagine them combined, to imagine them changing over time.
The organs of the sense of smell can be educated to the appreciation of perfume ingredients as easily as the palate can be educated to the nuances of teas, wines, or coffees. Because of the trace elements natural essences contain, their individual odors are complex, and they express the various elements of which they are composed in varying degrees of intensity as they evaporate. This is true even within a particular flower note: French tuberose, for example, is sweeter and more luscious than Indian.
We speak of a given essence as having a top note, a body note, and a dryout note. The top note is the first perceptible note that strikes the nose and can be of very short duration. Next is the body note, which is the main and characteristic odor of the substance; it has a longer life than the top note, lasting from fifteen minutes to an hour. The dryout note is the essence’s most lasting scent, becoming perceptible after perhaps half an hour and lasting for hours or even days. The transition from one stage to the next is, of course, a subtle melding rather than a radical shift; the body note gradually succeeds the top note and slowly fades into the dryout note. It requires experience to differentiate them readily.
It’s a good idea for a beginning perfumer to keep notes, in a special notebook or on index cards, of her impressions of the various aspects of each essence. Over time, these observations accumulate into a useful compendium of information and impressions. More immediately, the act of paying attention and recording heightens and hastens the development of an olfactory consciousness.
The great perfumer and perfume theorist Edmond Roudnitska, creator of Diorissimo and Eau de Hermès, had some wonderful ideas about how to begin smelling and describing as a perfumer:
Try to determine48 and record the quality and character of the odor (its note, its “form,” what it evokes or suggests); its stability or instability; the evolution of the note, its form in time (several days, several weeks); the duration of perceptibility. All these traits make up the attributes of the odor and give it a personality; they are inseparable and will have to be taken into account as a coherent whole. When introduced to a mixture, the odor ceases to be one entity and interacts freely with other odorous bodies.
Take note of everything that comes to mind, using the words which arise naturally; if they enable a thought to be more precise, if they surround the contours of the odors without ambiguity. Avoid “almost” at any cost. Try to find the words that unequivocally define the impression so that twenty years later, if confronted with the same impression, the same words come to mind.
Such precision is an ideal, not a reality, however; no essence can be described so clearly as to allow a reader to identify an unlabeled vial of the material with certainty. The complexity of natural materials is the source of their charm and mystery, and to resort to formulas or rigid comparisons is to miss what is most precious about them. As Steffen Arctander49, author of Perfume and Flavor Materials of Natural Origin, says, “Part of the ‘romance’ or ‘thrill’ in perfumery work lies in the fact that, not only are all the materials different in odor, but hardly ever will two perfumers give identical descriptions of the same material … An odor is not ‘woody’ just because someone else says so; it will always have a particular print in your mind. Unfortunately, you are more or less unable to translate this print verbally.”
Arctander’s book is the most important reference on natural fragrance materials. His understanding of the nuances of scented material is unequaled, and he knows how to convey those subtleties in comparison to odors with which the reader is already familiar. The sheer passion for natural perfume materials manifest in his description has more than once stimulated me to pursue some rare and unfamiliar essence. I lean on his book for my own descriptions of the individual essences, and I recommend tracking down a copy of it for yourself. Reading his descriptions of natural essences and comparing them to your own impressions is a terrific way to broaden your aromatic pale
tte and to learn about the nuances of scent.
Perfume blotters, or scent strips, are an essential tool for exploring the world of odors. They are strips of unscented, fairly stiff, absorbent white paper which resemble small paddles about five inches long by half an inch wide, tapering down to a quarter of an inch or so at one end. You write the name of the material you are sampling on the thicker end and dip the other end a half inch into the material itself, then smell. Perfume blotters can be purchased by mail order (see appendix), or you can simply cut thick watercolor paper into thin strips.
As I mentioned earlier, for the purposes of perfume composition, natural essences are classified according to their volatility: top (or head) notes are the most volatile; middle (or heart) notes diffuse more slowly; and base notes are the most lasting, or “fixed,” of all. We will explore each of these categories in detail, and the special properties they bring to a perfume as a whole, in the chapters that follow. For the moment, your task is to practice experiencing and evaluating individual scents, which reveal their own scent components as they diffuse and evaporate, displaying their top, body, and dryout notes before they disappear altogether. Some essences, like sandalwood, benzoin, and vanilla, have no top note, and their body note is also their dryout note. In other words, they hold true to their body note the entire time. Others—cedarwood, coriander, lime, lavender, and myrrh—possess a top note, but their body note does not evolve into a distinct dryout note. By observing and recording the evolution of each essence, you will become intimate with its character. When you become practiced enough, you will be able to determine for yourself whether a given essence is a top, middle, or base note. Top notes lose their scent rather quickly (six to eighteen hours), middle notes take more time (twenty-four to forty-eight hours), and strong base notes like civet, patchouli, and vetiver do not reveal their dryout note for many hours and may last for several days or longer.