Natural Perfume Materials: what the terms mean

There are quite a few methods by which the aromatic principles of natural materials are made available for use in perfumery and unfortunately some of the terms used are obscure and others are sometimes mis-used.

The purpose of this post is to set out the main terms used, together with definitions of widespread acceptance.  In putting these together I have relied on two main sources: first Arctander’s Pefume and FlavorMaterials of Natural Origin – written in the 1950s and early 60s but still regarded by most perfumers as the definitive work.

Second Brian Lawrence who is published regularly in Perfumer & Flavorist Magazine and elsewhere and is, probably, the definitive modern writer on the subject.

Before we get into the terms for natural materials, it is perhaps useful to examine what we mean by natural in this context and eliminate terms used to indicate synthetic materials.  Very few materials are suitable for use in perfumery exactly as they occur in nature: citrus oils and copaiba balsam are the main exceptions, requiring no processing beyond pressing the peel or releasing the balsam from the tree: in the great majority of cases processing is necessary and in some cases the odorous principles only form during processing (see my post on Bitter Almond Oil for an example of this).  A material is generally considered to be ‘natural’ when that processing is primarily physical, rather than chemical, in nature: these things are what this post is about.

Fragrance Oils are not usually natural

The term Fragrance Oil is widely used to indicate a blend of materials that may be both natural and synthetic, designed to replicate a natural odour.  These are often composed entirely from synthetic ingredients and almost never with entirely natural ones and as such do not fall within the definition of a natural material.  Occasionally they may be passed off as natural, sometimes innocently by traders who have themselves been deceived by a producer, but for the most part they are sold labelled as ‘fragrance oil’ and are usually cheaper than natural equivalents where these exist.

The main types of volatile isolates that are obtained commercially are essential oils, concretes, absolutes, pommades, resinoids, spice/herb oleoresins, extracts, infusions, and tinctures. The definitions of these, and some other important terms are set out here and for convenience I’ve started by listing first the three most common types – Essential Oil, Concrète and Absolute.  All other types follow in alphabetical order for ease of reference.

The most common natural materials

Bergamot in cultivation
(courtesy Wikimedia)

Essential Oil: The isolated aromatic portion of a plant that is borne in that plant within distinctive oil cells. In some exceptional cases the essential oil is formed during processing. Most essential oils are isolated by either hydro-distillation (water, steam or both) or cold pressing with some few being produced by dry (including destructive) distillation.  Water distillation implies direct contact between the plant material and the boiling water, steam distillation implies steam being produced separately and blown through the material – in the combined case the water is heated by injected steam.  Some essential oils are routinely ‘rectified’ after production – a process that may be entirely physical or may involve the introduction of synthetic aroma chemicals to standardise the odour.  Examples include Bergamot, which is routinely rectified to remove bergaptens (furocoumarins) – this is done by fractional distillation.  White Thyme is natural thyme oil that has been corrected by the addition of aroma chemicals to produce standardised oil chemistry – for most this would no longer be considered a natural product.

Concrète (often written as concrete with the same meaning):  an extract of fresh (cellular) plant material made using a hydrocarbon solvent, commonly hexane or petroleum ether. It is rich in hydrocarbon soluble material and devoid of water-soluble components. It is generally a waxy semi-solid, dark colour material free from the original solvent used in extraction, often containing a high percentage of largely odourless plant waxes.

Orris root being dried

One important note here on misuse of this term concerning Orris Butter, which is frequently called Orris Concrète, but is more correctly the essential oil of orris (the roots of certain species of Iris), which happens to be solid.  There is also a true Orris Concrète, from which a true Orris Absolute is made – the latter is a clear, mobile liquid unlike the so-called Orris Concrète or Butter which is solid at room temperature.

Absolute:  A highly concentrated alcoholic extract, usually of a concrète, which contains only alcohol soluble materials. Its primary use is in alcoholic perfumes but normally contains little or no residual ethanol.  Absolutes are also sometimes extracted from pommades (sometimes called Absolute from Pommade or Absolute from Châssis - the latter term is sometimes used to describe an absolute made by extracting the spent flowers already used in enfleurage).  An Absolute from Distilation Water (e.g. Rose Water Absolute) is also sometimes made using the hydrolat left over from making an essential oil as the starting material.  Sometimes the term Absolute is also used to mean the alcohol soluble fraction of a resinoid.

Other terms in alphabetical sequence

Copaifera langsdorfii 

Balsam: A natural exudate obtained from a shrub or a tree (either physiological or pathological). It is characterized by being rich in benzoic and cinnamic acids and their corresponding esters and is insoluble in water but completely or almost completely soluble in ethanol.  Balsams may, upon ageing, form resins and so the boundary between these two may be blurred.

CO² Extract – these include a range of extraction processes using carbon dioxide as the solvent.  In most cases the solvent used is rendered liquid at much higher temperatures than normal an so the extract produced is often, more correctly, referred to as SFE – supercritical fluid extract – and I’ve said a bit more about it under that heading.

Extract: A concentrate of a dried less volatile aromatic plant part obtained by solvent extraction with a polar solvent.  In practice this term is used quite indiscriminately to mean several of the types of processed material where there result is concentrated – with the solvent removed.  In flavour work the term is used even more widely to include emulsions and diluted materials that may be water soluble (possibly dissolved in water) and of very short shelf-life. To be meaningful this term really requires further qualification or clarification and perfumers should approach ‘extracts’ with appropriate caution.

Note that the French term ‘extrait’ (directly translated this would be extract) is used in English to mean something quite specific: An alcoholic extract of a pomade produced by enfleurage: a tincture of a pomade.   The term is also occasionally hijacked to mean an alcoholic dilution of any material of a particular strength or a blended perfume of a particular strength “extrait strength” is sometimes used to mean much the same as Parfum, that is an alcoholic perfume with 15-30% aromatic ingredients.

Gum: Can be either a natural or synthetic material but, strictly, should be used only for water-soluble materials of very high molecular weight.  In perfumery it can, however, also be used of resins and turpentines.  Under the strict definition gums are odourless and therefore of no use in perfumery.

Commiphora myrrha tree one of the primary sources
from which the oleo-gum-resin
myrrh is harvested.

Gum Resin: A natural exudate obtained from a tree or plant. It is comprised of gums and resins. If the gum resin source also contains an essential oil, it is called an oleo-gum-resin.  Only partially soluble in alcohol, hydrocarbons etc. and may be partially soluble in water where the proportion of gum is significant.

Infusion: A hot extraction of either a plant part or its exudate with either water or an organic solvent. Infusions are not at all popular because it is difficult to control their chemical composition.

Isolate: sometimes clarified as natural isolate, this is prepared material, produced from a precursor of natural origin, most often an essential oil, by any of a range of physical processes including fractional distillation or freezing, chromatographic separation and others.  At one time many perfumery materials were made this way that today are available much more cheaply as synthetics.  Natural perfumers may still take advantage of the fact that many natural isolates continue to be produced commercially for the flavour industry where the premium on natural flavours justifies the increased cost of production.

Oleoresin: The natural tree trunk or bark exudate, which is extremely rich in an essential oil.  The term is occasionally also used of prepared materials.  In either case they consist of essential oil and resin.  Turpentines are oleoresins where the resin portion is acidic.

Pommade:  The product of the enfleurage fat extraction of fresh flowers. Enfleurage was once much more widely used than today but is still the most efficient (highest yielding) method with certain flowers that continue to manufacture perfume in the flower after it is cut, such as tuberose for example.

Resin Absolute: generally applied to materials obtain directly from plant raw-materials by extraction with hot alcohol: once the alcohol has been recovered, what is left is referred to as the Resin Absolute.  As the product is often very thick and sticky, the recovered alcohol may be partially replaced by a high-boiling solvent such as Isopropyl Myristate when it is usually sold as ‘mobilised with N% of XX’.  Notable exceptions include the extraction product of Oakmoss with hot alcohol, which is usually called Oakmoss Resin; that of Orris is likewise called Orris Resin.

Benzoin resin from which Benzoin Resinoid is made

Resinoid:  A solvent extract of a resin-rich material containing natural exudate or dried plant material with a hydrocarbon solvent. Resinoids are generally viscous to semi-solid mixtures. They can be considered as being equivalent to concrètes but made from dead / dried (non-cellular) materials.

Spice/Herb Oleoresin: A solvent extract of a dried spice or herb, which is virtually free from the extracting solvent. It is used more-or-less exclusively by the food and pharmaceutical industries as a replacement for ground spices and spice tinctures.

Supercritical Fluid Extract This is an extract made using supercritical carbon dioxide (CO²) or another suitable supercritical fluid material as the solvent. Supercritical fluid extraction (SFE) of plant material with solvents like CO²,

propane, butane, or ethylene is increasingly being done. SFE allows the processing of plant material at low temperatures, hence limiting thermal degradation, and avoids the use of toxic solvents.  A common downside of SFE is that the resulting material may not be fully soluble in ethanol and in many cases further extraction with ethanol to produce, what is in effect an Absolute from SFE is conducted – these are sometimes sold as CO² Select Extract or, more intuitively as Ethanol Soluble SFE.

Tincture: An alcoholic or aqueous alcoholic extract of a natural raw material in which the solvent is left in the extract as a diluent. Tinctures are used both in the fragrance and pharmaceutical industries. The amount of alcohol in the tincture, which ranges from 20-95%, is standardized by the manufacturer.  See my post on Ambergris for an example of a tincture used in perfumery

 

Perfumery Talks at Shropshire Lavender

For a great day out this weekend 13th - 14th July, come along to the Shropshire Lavender Farm where I'll be giving talks at 12.30 and 14.30 on perfume, what it is, how it's made and what's really in it.

There will be ingredients and blends for you to smell to illustrate the talk and an opportunity to ask questions.  Book via the Shropshire Lavender Events page.

The farm is open all weekend and features lavender in every guise including cakes to die for!

Pell Wall are mell for perfume
at the Shropshire Lavender Farm 

The event was featured in the Shropshire Star last Saturday - very nice article marred only by getting the name of the business wrong: it's Pell Wall not Pell Mell Perfumes, though Pell Mell isn't far from the truth here sometimes ;-)

A perfume that becomes a film star

This is a guest post by Susan Feehan and in introducing it I feel I should explain that, other than my friendship with perfumer John Stephen, I have no connection with the project she's talking about here: I just thought it was such a great idea it deserved some publicity and was sure to interest people who are interested in perfume. Over to Susan:

Fire breaks out at a famous London hotel. A bathrobed hero emerges from the flames carrying the woman who loves him. They kiss and find themselves on the world’s front pages; their moment of passion and courage inspires a new perfume. Then our hero goes back to his wife…

Time goes by…everyone forgets…until a perfume campaign offers the couple a big fat fee and a return to the spotlight. What could possibly go wrong?

If that sounds like a pitch for a romantic comedy, you’ve guessed right. I’m the writer, and I can’t resist pitching. You never know when a hedge fund manager might be reading…

Seriously, every film story needs a crucible in which characters are trapped until they work through their demons or face ruin. I always knew mine would be the world of perfume, but for several drafts I didn’t know why.

I thought it was about glamour, fantasy and a serenely calm and fragrant public world at odds with the story’s private arena of anger, old grievances, betrayal, insecurity and…yes, it is still a romantic comedy.

Then I realised perfume had to be at the heart of the story because it is about the memories that surround one moment captured in a picture. Memories that differ for each character.

Linda — the leading lady who is rescued from the hotel fire and then dumped by her married lover — can’t remember the moment for what it was: an honest and true moment when two people forgot their emotional ties. All she sees is a man she loved who was about to dump her. She only remembers the moment’s future.

Harry — the fire hero — sees the moment and remembers how his courage collapsed into cowardice because he wasn’t sure he could be that man for the rest of his life.

Steve — the man who replaced Harry in Linda’s heart — sees Harry’s and Linda’s big moment and fears he’s not made of that kind of heroic stuff.

Ralph — the photographer who made Harry and Linda famous — remembers snapping two people who had cheated death, who had looked the devil in the eye and said: ‘Not today. We’re in love, and you can’t touch us.’

Pierre — the perfumer so inspired by the moment that he turns it into a fragrance — deludes himself that the moment can return exactly as it once was, if only he can reunite the couple who were his muse.

These are a few of the people I spend my life with. Writers need to find themselves in each of their characters and Pierre hits a major nerve with me. He’s ridiculous in many ways, too precious to operate in the real world. He channels perfume from a universe not known to mere mortals, coming to life only when talking about fragrance and protected from reality by his adoring wife Christine.

Well, I regularly become pompous and authorial about writing generally and film stories in particular. Then I can’t be bothered about the nitty-gritty of real life. Pierre cries when his creation is dragged through the dirt by the very people who inspired him, and cries again when he feels his world is ending. Again, er…me. And, like me, Pierre often wears sunglasses indoors — sometimes to hide the tear tracts on his face. How can you not love him?

He deserves a reward for being put through hell. He deserves more than a fictional perfume. He deserves a real one. So we’re going to make life imitate art. Why shoot a film with a mocked-up perfume that’s probably tea in a bottle when you can have a real fragrance, inspired by the same moment in the story?

But I’m a writer, not a perfumer. So I’ve found our real-life equivalent of Pierre — John Stephen, of The Cotswold Perfumery — who is creating a character I can write, but can’t cast. John can bring this character off the page and into real life. In time, we hope that you can not only see the film, but also buy the perfume. If there are any hedge fund managers reading, that was another pitch for funding…

We want romance, courage, fire, honesty and forgiveness, all in the one bottle. So no pressure, John. Before he bolts for the exit, I should stress that no real-life perfumers will be harmed in the making of this film…

You can find us on Facebook at thekissmovie, on the web at thekissmovie.uk.com and fundraising on indiegogo (at http://bit.ly/12Ztina until 5 August) with perfume perks as our thanks for support.

                      Susan Feehan

A bomber, a golf course and an uncle

Just before I come back to those things I trailed in yesterday's teaser post I wanted to say a little something about my remarkable uncle Basil Ambrose, who turned 90 recently. Few of those heroes who flew Lancaster Bombers in World War II have survived so long and there can be fewer yet who are still so active.

I've recounted some of his story here, adapted from a press release by the Goring and Streatley Golf Club, where Basil celebrated his 90th Birthday with a party and also by being on the course at 7.30am to tee-off: now that's what you call keen.

Basil in the local paper

Born 1923 in Derby Street, Reading, Basil still lives nearby in Langley Hill, Tilehurst. A golfing veteran, Basil started caddying at 16 years of age and was on the course the day war was declared. He didn’t hesitate to join Air Raid Precautions (ARP) as a messenger boy and remembers being on Langley Hill the day bombs were dropped.

“I heard aircraft flying overhead and noticed a half circle of light. Suddenly it sounded like an express train coming though the air. I realised immediately what was happening and dived into a ditch by the side of the road. My family were frightened to death. Bombs went right up Langley Hill. We were lucky not to have had more casualties.”

At 18, Basil resigned his apprenticeship as a metal turner and joined the Home Guard, and then later the Royal Air Force. Training at various bases in the UK, he passed out with top grades to become a Leading Aircraftsman. In his role as a flight engineer, Basil helped pilot huge 4-engine Stirling bombers, later converting to Lancaster bombers with 467 Squadron.

Avro Lancaster R5868
in the Bomber Hall of the RAF Museum London
courtesy Wikipedia

By 1944, Basil was flying daylight support operations over the Netherlands and night raids over Germany. Basil talked about one particularly difficult night raid.

“We’d reached our target in Germany but the rest of the force had gone, so we were alone. As soon as we dropped the bombs, the rear gunner spotted a fighter coming in. He gave the instruction to corkscrew but the skipper knew that to lose the search lights he’d have to do something entirely different. He stood the plane on its nose and we dived 5,000 feet. I was pinned to the cabin ceiling. When we pulled up, I was forced to the floor. Then we dived another 3,000 feet. We took some flak and lost an engine but made it home in one piece.”

Wearing his France and Germany Star, and 1939-1945 Star and War Medal at his birthday celebrations, Basil has certainly earned recognition for his bravery and service.

"I was there to do a job, we didn't want to let anyone down"
Basil Ambrose in characteristic style

At the end of the war, Basil returned to Langley Hill, working at Cook’s Dairy Farm Equipment using his engineering skills. He later joined the Atomic Weapons Research Establishment in Aldermaston as a mechanical safety officer and the Greater London Council as chief safety advisor, before taking early retirement.

Basil with his son David

Looking for a hobby, friends recommended Basil join Goring and Streatley Golf Club. He’s now been a member for three decades and his family are regular visitors too for family celebrations. Basil’s brother-in-law, Dennis Bartlett, had his 90^th birthday party there and three Bartlett cousins jointly celebrated their 40^th wedding anniversaries there too. Liz Bartlett, Basil’s sister-in-law, commented on how the family holds its ‘cousins’ lunch’ at the club every year, coming from as far as Shropshire, Somerset and the West County to join in the celebrations.

Cyril Bartlett

Basil isn't the only hero in the family either - he joined the Bartlett family when he married Jean, who's father Cyril Bartlett, my grandfather, was a soldier in the First World War and is the subject of a book and website that tell the story of his war through his letters to Jessica: the lady who was to be my grandmother.

As you might imagine, we're quite proud of our family heroes!

A teaser

I've been a bit quiet on this blog for a couple of weeks so I thought I'd do a little teaser of some things in the pipeline to keep you interested:

Coming soon is my first Guest Post from writer Susan Feehan who will be talking about a remarkable project involving a perfume, a film and a crowdsource (not a perfume called Crowdsource you understand, but a real crowdsourcing project) which also happens to involve my friend and mentor, perfumer John Stephen.

A Perfume, a film and a crowdsource

Shortly after that I'll be looking at some of the terms used to describe the various natural materials used in perfume in an attempt to clarify the differences: so if you're not sure of the difference between an absolute and an oleo-resin, stay tuned.

A bit further on and I'm planning a series of posts exploring some of the ethical issues in perfumery: from endangered species to biodegradable ingredients.

Hopefully there is something there to intrigue and interest you.  And if you're a writer and fancy doing a guest post too, let me know: the only rules are it has to be interesting and have something to do with perfume, perfumery or Pell Wall.