The essence of essential oils

A client the other day was looking to use Neroli oil in a fragrance. Neroli is known in aromatherapy for its effect on reducing anxiety and bringing a sense of peace and tranquility, so that is what the client wanted to infuse into their fragrance. However, it is a very expensive fragrance component at up to NZ$35,000 per kg and the choice had to be made between using two different Neroli oils, one being one third the cost of the other. Usually, we associate a difference in a material’s cost with a difference in quality. Although, let’s face it, in the world of perfumery, a well known brand name alone can demand high prices without any discernable association with quality, but such brand names don’t typically extend to individual fragrance components. The question then arises as to why the difference in cost and therefore what, exactly, is Neroli Oil and what gives it those particular mood-enhancing properties?

Neroli oil is an essential oil that is produced in various countries (France, Italy, Egypt, Tunisia, Morocco and others) from the flowers of the bitter orange tree by steam distillation. That said, the oil composition will depend on the region and conditions under which the tree is grown, the soil type, whether the season has been particularly wet or dry, hot or cold. Also, the time during the season and even the time of day the flowers are harvested, how they are stored or transported, and the operating conditions of the steam distillation process.

What affects the price of the final Neroli oil will come down to the economic conditions where it is produced, the costs of transport, the history and mystique of the geographic origin, and so on but, arguably, also the quality of the oil. This is where it gets tricky because, as mentioned above, not all oils will be the same, so who defines the quality and on what basis? One might also consider that there must be one or more unique components in the oil that give it the mood-enhancing properties it is renowned for. If you search online for the main components of Neroli oil, you will find common reference to Linalyl Acetate, Linalool, Geraniol, Farnesol and Citral. It cannot, surely, be just components such as these, which are commonly found in many other essential oils – otherwise all the other oils that contain these components would have similar effects on mood. Of course, it could be some kind of synergistic effect, that comes from a particular proportion of those components but we’ll come back to that. 

So, should one look for specific components that relate to the name “Neroli”, such as Nerol, Nerolidol or Neral? Perhaps we could but these components are typically present at quite low concentrations so it would seem strange that they would be the components responsible for the perceived benefits, and they are not mentioned by most common information sources. Besides, let’s not get too attached to what components are called. Neroli oil itself was simply named after a 17th Century princess of Nerola in Italy – the individual chemical components were probably named by the scientists who first isolated them because of where they were first identified, not because they imbued the oil with any particular properties. Besides, they are not uniquely found in Neroli oil – for example, Nerolidol is found in ginger, lavender and lemongrass essential oils, amongst others, while Nerol is found in roses.

Clearly, though, Neroli oil has a distinctive fragrance that is recognisably Neroli, even if the specific composition differs from one oil to another. In the case in point, one oil has notes that are closer to the sweet, rounded, narcotic aroma of the orange flower (which is extracted from the same flowers but using solvents rather than steam distillation); the other leaning more into the sharp, green notes of Petitgrain essential oil (which is produced from the stems and leaves of the same tree, also by steam distillation). But both have distinctly Neroli fragrance profiles. Whether they both have equal effects on mood is questionable and I don’t know of any study that has explored that.

Is there some other, as yet unidentified “magic” fragrance component responsible for Neroli’s reputation? That seems unlikely, with all the modern chemical analytical methods that are available, so we go back to the idea that there is some kind of synergistic effect of the combination of components in the oil. Unfortunately, we have to address the inherently tricky situation that the oils have differing chemical compositions. Let me list the four most abundant components of the two oils in question here.

Oil A: Linalyl Acetate 34.2%, Linalool 15.3%, Limonene 15% and Geranyl Acetate 6.4%. Also, Nerolidol 1.1% and zero Nerol or Farnesol.

Oil B (three times the cost): Linalool 21.4%, Limonene 12.2%, Beta Pinene 11.7% and Geranyl Acetate 7%. Also, Nerolidol 4.8%, Nerol 1.1% and Farnesol 3%.

Clearly, these oils have very different compositions and in some cases characteristic components are missing altogether. The most abundant material in Oil A, Linalyl Acetate at 34.2%, is only present at 6.7% in Oil B. If the mood-enhancing effects of Neroli oil can be ascribed to a synergistic balance of its components, then we are in trouble here, because the balance is completely different in each oil. How can we expect the same effect from both oils? And which one is better – the expensive one or the lower cost one?

This all raises more questions for me than answers but it does underscore that the need for us to better understand the characteristics of natural products and to determine the active components rather than blindly accepting all claims, based solely on a name or a particular raw material source and production method.