Chemical romance: How did chemists become the greatest force in fragrance?

Few perfumes are crafted by hand in a dusty atelier. Instead, they come to life in the lab.

A perfume, any perfumer worth their jasmine absolute will convince you, begins with inspiration. For the Lush perfumer Simon Constantine, when he set about creating a collection of scents for the launch of new fragrance house Gorilla Perfume, that meant bottling Lust, The Smell of Freedom, Orange Blossom, an Italian dance called Tuca Tuca, and even the sweet, ingenuous whiff of Imogen Rose, his new baby.

Both Simon and his father, Mark, a co-founder of Lush, say they want to reinvigorate the perfume market. Hundreds of similar fragrances are launched each year, mainly by the five big perfume houses, and in a fragrance market worth £1bn in sales, last year 46 per cent of product was shifted in the Christmas holiday period, despite striking similarities between many of the products.

This is not simply a case of coming up with the most innovative, or outlandish, idea for a perfume. The smell of money and cheese have been bottled and sold. The Constantines have even made edible and drinkable perfumes to showcase their new scents. Yet the art and inspiration must be met by science, which binds all perfumers.

Scent science dictates what raw materials are available to them, and their cost. Perfumery might seem like the most flimsy of sciences, and you do not, indeed, need a chemistry degree to mix a decent scent, but bottling a smell is much more complicated than deciding you like the smell of this or that flower or herb, boiling it up and dabbing a spot on your wrist. The idea that any scent is a field-to-fragrance distillation of an English country garden, Moroccan spice bazaar or meadow of lily of the valley is a marketing construct.

"Natural" is perceived as a good thing, whereas "chemical" is bad. In fact, almost all perfumes end up being a blend of natural raw materials and synthetic raw materials. Even perfumers who like working with natural ingredients need synthetics.

The natural materials, mixtures of molecules, are sold to perfume houses by extraction firms. But they need help to become the smell the perfumer is after. Simon Constantine wanted an orange blossom to communicate his childhood holidays on the Mediterranean, but the classic orange blossom oil has a dense, tarry smell. Eventually, he found a high-quality orange blossom absolute and mixed it with neroli to get the honeyed, sunny experience he craved.

"Naturals are the beauty of perfumery," explains Lyn Harris of luxury fragrance house Miller Harris. "They link back to the heritage and are what inspire me the most. But it would be wrong to say that I prefer them over synthetics."

Synthetic ingredients exist for a variety of reasons. Naturals do not always smell the same when extracted as they do in nature, and need to be "rebuilt" synthetically. Strawberry, banana and pineapple flavours are always synthetic. Synthetics are often much cheaper than a 100 per cent natural ingredient (cost dictates much of a perfumer's work; a decade ago, a fine fragrance might have cost £200-£300 per kilo. Now, £100 is expensive (and £15 much more likely). Perhaps most importantly, synthetic raw materials, usually single molecules, enable perfumers to create entirely new smells for us to enjoy. "I would never want to do without chemicals or synthetics as these are what add the magic to a formula," Harris says.

The first time a synthetic material was used in a commercial scent was in 1881, when Paul Parquet used synthetic coumarin in his Fougère Royale fragrance for Houbigant. The name translates as royal fern – the joke being that ferns have no smell, so Parquet had created a smell out of nothing. Coumarin is present in many natural products which Parquet had access to, but making his own meant he could use it in huge doses, creating an altogether different effect to anything else on the market.

More than 100 years later, single-molecule smells, on their own, rarely resemble anything we recognise. No doubt Geza Schoen's Escentric Molecules, single-molecule scents, are a success precisely because they smell so peculiar.

The five big perfume houses (Givaudan, Firmenich, IFF, Symrise and Takasago) make fine fragrances and smells for soaps, cleaning products and anything else we use that is scented. Their perfume scientists work hard to create new molecules, the secrets of which are then fiercely guarded. The senior vice-president of fine fragrance creation at Symrise, Beatrice Mouleyre, explains that in the Givenchy Play range, Ambroxide, one of Symrise's specialities, gives the dry, woody note in the men's fragrance. Symroxane, a Symrise "captive", is in the women's fragrance. If you want to make a new scent and enjoy Givenchy Play's complex woody facets, you should turn to Symrise.

Although Constantine's laboratory in Poole is tiny compared with those at the big perfume houses, all perfumers use the same, fairly simple, apparatus – bottles, pipettes, beakers, scales. The complex bits are the ingredients. These are mixed, drop by drop, until the right blend is reached. The oils are mixed with alcohol to reach the desired concentration. Each new fragrance is left to sit for at least a week, because the smell will change over time, before settling, just as perfume does on your skin.

There are so many potential smells available to perfumers, it is a wonder they ever achieve what they are aiming for. But, as celebrated fragrance scientist Luca Turin explains in The Science of Scent, perfumes can be thought of as "chemical poems" made up of hundreds of words. Each word can be followed by a number of potential words, but not by anything at all. You can't read a poem backwards or vertically and come away with the same overall effect the poet intended, but you can make minor adjustments with punctuation and small word changes and create your own unique variation on the original.

Rose was once considered something of a "granny" smell but has experienced a boom in popularity in recent years. Constantine wanted to create an entirely new rose sensation when creating a perfume in honour of his new daughter. What he has managed is a genius stroke of bottling a fresh, clear rose scent along with the Johnson's talcum powder sweetness of a baby. Of course, he didn't get there by mixing rose oil with talc and Johnson's Baby Oil. He added basil notes to the Damascus rose oil to give the flower a greener, fresher smell. The talcum powder hug was found by mixing tonka bean with rose absolute.

When Constantine launched the scent at a specially created "fragrance gallery" in Tokyo earlier this month, its effect was palpable. Fragrances are typically associated with sophistication, and certainly adulthood, yet here was a smell that transported every wearer to the playfulness of baby bath time.

The fun, and the challenge, of scent for scientists and perfumers is its malleability and endless potential. When Lyn Harris created one of her original and best-selling scents, Fleur Oriental, she added fresh orange flower, heliotrope, spicy carnation and rose to the "great and grand orientals". Florals and orientals are considered two different categories of scent, but Harris successfully blended the two into one of her signature creations.

This is how small perfumers, who do not have access to captive molecules, make their mark on perfumery and are able to shake up the industry. Yet while perfumers can influence what we smell, they cannot affect how we smell their work. The chemistry of scent is up for grabs – anyone can have a dabble – but the biology of smell is a much greater mystery.

Making sense of scents

Smell is the most complex and mysterious of all the senses. Deciphering how it works – ie how we smell things – has been a major headache for scientists throughout the 20th and 21st centuries.

The ability to decode smell would have a far greater reach than the perfume industry. One idea under trial is the creation of artificial noses. These fake noses (called RealNose!) could – one day – replace drug- and explosive-sniffing dogs and have numerous medical uses.

Humans have an extensive olfactory system with around 400 functional genes. Dogs and mice have around 1,000. Each smell activates a number of these smell receptors in a certain pattern. This pattern is recognised by the brain as a particular scent.

It has been difficult to reproduce these receptors because they are membrane proteins, which lose their structure when removed from the smell molecule which activated them.

The breakthrough happened at the Massachusetts Institute of Technology (MIT), where a team found a way to isolate the proteins without their breaking down, so they can now study and reproduce them. The aim is to develop a portable microfluidic device which will be able to identify an array of different smells. This could be used in medicine for early diagnosis of diseases that produce distinctive smells, such as diabetes and lung, bladder and skin cancers.

This is only a small step on the path to fully understanding our sense of smell. "Smell remains a tantalising enigma," MIT's Shuguang Zhang says.