Art Meets Science: The Technical Fundamentals of Perfumery – CPS lecture 7

By Penny Carmichael, on 26 November 2012

-Article by Abigail Mountain

All term people have been asking if there was a typo on the talk list, but at last on Tuesday night it was confirmed that it is not our own Andrew Wills who has a secret passion for odour. Will Andrews from P&G was the man who wowed the Ramsay lecture theatre this week, bringing a crowd so big that people were sitting on the stairs – rather reminiscent of a second year Inorganic class.

Not being a chemist, he explained that he wasn’t on the early development side of the industry, his trained nose is instead used to evaluate odours in the fragrance design team. With ten different bottles for us to smell he began the interactive lecture by passing around a manly aftershave odour. He asked the audience to describe the smell using the other four senses. Would it be soft? Cold? Sweet? Bitter? What colour would it be? Was it high-pitched? A plethora of contradicting descriptions were given, except when asked what it smelled of… We all fell silent. He had used this exercise to demonstrate that there is no universal vocabulary for odours. Indeed, companies in the fragrance industry use all of the senses to describe smells.

The room was divided about whether or not what we were smelling was actually nice. This introduced us to the idea that perfumes are trying to evoke a memory or character to a product. We will like an odour if we have a positive memory associated with it and this was proven to me when a pot of something that I’ve not smelled in nearly twenty years brought an overwhelming comforting  feeling over me; play-dough. Again, some people just did not enjoy it, showing that fragrances are incredibly subjective.

The second smell passed around was that of rose. This one odour contains over three hundred different aromatic compounds and yet most of us would instantly recognise the smell. It’s still not known for sure how we do this, but what is clear is that our noses are very powerful tools. It’s believed that some smell recognition is genetic, for example being able to smell burning, and that we use it to detect danger.

We moved on to smelling different types of natural products used in building up a complex fragrance. Orange/lime, cinnamon, and vanillin were top-notes, heart-notes and bass-notes, respectively.  Top-notes have the lowest molecular weight and are therefore most easily evaporated from the skin, typically lasting only half an hour. So if you thought your citrusy expensive perfume was a rip-off because it wasn’t lasting all day, don’t worry – it’s just physical chemistry in action! Smelling all three together was surprisingly familiar but no-one could put their finger on it. When it was revealed to be Coca-Cola the whole room erupted in amazement.

After sniffing natural vanilla and star anise we moved on to synthetic smells, the last of which was that sickly sweet strawberry smell used in bubblegum and shampoo. Perfumers need to make synthetic products because we’re not able to extract the odour of natural strawberry, for example, due to the processes involved. Steaming or hot solvent extraction would simply turn the strawberries into a mush; similarly with any soft fruit. Other natural products are just too scarce to be able to make any decent volume of extract. In these cases we can capture the smell and analyse the odour compounds using gas chromatography-mass spectrometry (GC-MS). Theoretically we can capture any smell, it’s getting the mixture of the compounds right when reproducing it that is the tricky part.

Will Andrews did a great job of waking everybody up after a long day at work with discussions, nostalgia and a thoroughly interesting lecture. Certainly everyone I spoke to after the lecture had decided that they wanted to become a perfumer.