Flower and fruit aromas in perfumery
Chemistry’s own scent
As unaware as we may be, we live in a world dominated by aromas. Our sense of smell is able to precisely detect thousands upon thousands of distinct chemical compounds. Some researchers estimate that the human nose is able to experience even a trillion different scents! With the development of modern chemistry techniques, we have been able to identify the main components of specific aromas and use them for their addition in various cosmetics, personal care products and perfumes. But knowledge about the field of aromas is not only critically vital to the perfume industry, but also to the greater field of organic chemistry. In fact, Nobel Laureate Leopold Ruzicka once stated that "straight from the beginnings of scientific chemistry to the present day, fragrances have significantly contributed to the evolution of organic chemistry in terms of methodology, systematic classification, and theory".
The study of aromas and perfume components was a very important driver for the applied research of organic chemistry throughout the twentieth century. From all the pleasant aromas that we are able to experience, flower and fruit scents tend to stand out among the most liked ones. Almost everyone has a favorite smelling flower and can identify the different fragrances of certain fruits. The chemical landscape that surrounds the fascinating and intricate world of fruit and flower scents shows a massive amount of compounds to explore!
Plant volatiles and their function
Floral scents and fruit aromas fall into the wide category of volatile organic compounds, often abbreviated as VOCs. VOCs, in essence, refer to usually small and relatively simple organic molecules that tend to evaporate with ease. This remarkable characteristic enables many VOCs to quickly diffuse into the air and to travel in it, allowing our sense of smell to readily perceive them.
Plants can use up to 10% of the carbon they fix during photosynthesis for the production of different VOCs. That is a huge figure! But with this great cost comes an even greater benefit. These compounds play key roles in the attraction of pollinators and seed dispersers, defense against herbivores, protection against pathogens and plant to plant communication. Moreover, certain VOCs are also able to protect plants against certain abiotic stresses, such as temperature, or oxidative stress.
The composition and abundance of these VOCs in different fruit and floral scents vary widely among flowering plants. Each plant has adapted to prepare a specific concoction of these VOCs; tailor-made to its own specific requirements. The emission of certain VOCs by a plant also varies at different times of the day, usually to match the time that their pollinators or seed dispersers are the most active. For example, the snapdragon (Antirrhinum majus), a common garden flower that is mostly pollinated by bees, shows the highest emissions at noon, when bees are busy looking for nectar.
Fruit and flower esters
A particularly interesting group of VOCs are the so-called flower and fruit esters which generally possess a sweet and pleasant aroma. This family of volatiles play a rather important contribution in the final aroma of fruits and flowers in question. So much so, that they are usually the main or even only chemicals that are added to certain products to replicate certain flower and fruit scents.
Their names can get a little bit complex, but they are usually composed of two words, the first one ending with “-yl”and the second with “-ate”. Some examples of these esters in flowers can be found in gardenia and jasmine, both of them owing a great part of their scent to benzyl acetate, lavender, to linalyl acetate and lily, to methyl benzoate. There are even more examples for fruit fragrances. Grapes owe their aroma to methyl anthranilate, raspberries to isobutyl formate, apples to butyl acetate and bananas to isoamyl acetate. In the case of apples and bananas, their different esters are so important in determining fragrance that these compounds, usually solely, decide whether a perfume or even some types of sweets bear their particular aromas.
Flower and fruit esters in the perfume industry
The word perfume comes from the Latin perfumare meaning “to smoke through”; referring to the volatile nature of these preparations. This volatility is highly specialized. Classical perfumery revolves around three notes or “levels” of volatility. The first note corresponds to the scent that the perfume releases when it is first applied. The second note corresponds to the main scent of the perfume, which is the strongest and longer lasting. Finally, the third note is the “aftertaste” of the smell, which is usually less strong, but long lasting. The balance of the aforementioned notes generates a pleasant perfume. The specific components of floral perfumes were traditionally extracted from their respective plants of origin; and still are to some degree nowadays. Using the whole flower or fruit extract has the advantage of providing a more accurate aroma of the actual plant of origin, as all the different compounds present end up in the formulation. However, the relative simplicity of many floral and fruit esters enables for their mass production in industrial settings, relying on their chemical synthesis rather than in its isolation from natural sources. This is especially relevant if only the main component of the flower or fruit aroma is required and allows for a more cost-effective synthetic production.
For more interesting articles diving into the fascinating sphere of plant science, keep checking this space!
By David Alzuria Rodríguez | 27 September 2022
David Alzuria Rodrguez is a Spaniard from Barcelona. He holds a master's degree in plant biotechnology. He recently began performing plant science communication for Lab Associates in the form of short articles about plant-based cosmetics and pharmaceuticals. He has always been fascinated by nature and how it interacts with human societies. As a result, he decided to create an Instagram page, @plant_chem, dedicated to plant secondary metabolites as well as their properties and applications. He enjoys spending his spare time with friends and family, gardening, and hiking in the mountains.
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