I am a chemist and I regard chemicals as my friends. Just like people, they all have their own personalities and there are some you like more than others. Also like people they all belong to families and the families themselves also have personalities. Some can be a bit dull. Hydrocarbons for instance are plodding, pedestrian and predictable. They are only made of carbon and hydrogen and they don’t do very much interesting. The hydrocarbons are a sort of lumpenproletariat. There are a lot of them around and we would be lost without them and the work they do, but they don’t often command any attention.
The family I am most fond of is the terpenes. These are a bunch of charismatic characters who seem to pop up in the most interesting places and often surprise you with what they get up to. The definition of a terpene is a bit dull but you don’t really need to know what it is. Like elephants, you can recognise one without knowing how to define it. In fact what I think of as terpenes goes a bit beyond the standard definition. (For chemists reading, I tend to include aromatic compounds that arise as secondary metabolites given that they have the same ecological significance. I know it is technically wrong, but it seems to me a bit like the argument about whether a jaffa cake is a biscuit. You find it on the biscuit counter and you treat it like a biscuit.)
The place you most often come across them is in essential oils. Examples are geraniol, limonene and menthol so you can see from the names that they are linked closely with plants. Most terpenes were found originally in plants.
The terpene (or something very closely related to terpenes) I want to talk about is vanillin, which as you might guess, was first isolated from vanilla. It has a very distinct sweet odour and is often used on its own as a vanilla flavour. The reason it is on my mind at the moment is that it gives the Waitrose Baby Bottom Butter its distinctive smell, which some people have likened to vanilla ice cream. Well there is a good reason for that. Vanillin is the smell of vanilla ice cream. In fact I think most people think of the smell of vanilla as that of vanillin. When you smell real vanilla, although it does have a rich and interesting smell, it doesn’t really smell as vanillary you expect.
As I said, the terpenes often surprise you when they turn up where you least expect them. Vanillin did this to me when I came across a paper in a pediatric journal where vanillin had been used in a study to see whether familiar odours can calm down babies. In the study they found that babies that were used to the smell of vanillin were calmer than normal when their mothers left them if they were exposed to the smell of vanillin. They found the same effect from the smell of the mothers’ breast milk. From the way the study was conducted it wasn’t clear if this is a unique property of vanillin or if any distinctive smell would have had the same effect. But for me, it was a familiar feeling of being surprised and delighted by my favourite family of chemicals.
RATTAZ, CECILE Ph.D. 1; GOUBET, NATHALIE Ph.D. 2; BULLINGER, ANDRE Ph.D. 1 The Calming Effect of a Familiar Odor on Full-Term Newborns. Journal of Developmental & Behavioral Pediatrics. 26(2):86-92, April 2005.