This is the second part in the series of ‘The bitter orange tree: bigarade, petitgrain, orange leaf, neroli, and orange blossom’.
The main extracts from bitter orange leaves are petitgrain oil and orange leaf absolute.
Petitgrain oil is produced by steam distillation of leaves and twigs of the bitter orange tree (Citrus aurantium subspecies amara). The video below shows a traditional petitgrain oil production in Paraguay. Traditionally, the branches are harvested manually with machetes and transferred to the on-site distillery. The wood still is filled with the harvested leaves and branches before it is covered with a lid and sealed with wet clay. The resulting petitgrain oil is immiscible and forms a layer on top of water. Usually, 500 to 600 kg of leaves and twigs yield 1 kg of petitgrain oil.
The oil is intensely bittersweet, woody, fresh floral, and with a green undertone. It is mainly produced in Paraguay from October to March, but a higher-grade oil comes in small quantities from France, Southern Italy, Morocco, and Tunisia in June and July. Petitgrain oil from Paraguay has a characteristic bitter green note with a slight floral touch of neroli oil. Tunisian variety possesses also a bitter green note, but is the most floral amongst the origins of petitgrain oil.
Sometimes, the leaves are solvent-extracted, and around 500 kg of leaves yield 1 kg of orange leaf absolute. It has a powerful bitter green note, but is a step down from petitgrain oil; its dry down is soft and with a marine facet. Interestingly, even the water by-product from the steam distillation of the leaves and twigs can be further solvent-extracted. It takes up to 3300 kg of leaves and twigs to produce just 1 kg of orange leaf water absolute that has a deep bitter green note precisely recalling plucked leaves. It is also slightly smoky and long-lasting. In any case, I imagine these two types of absolute to be incredibly expensive!
In terms of composition, petitgrain oil can comprise up to 80% of the 2:1 mixture of linalyl acetate and linalool. There are also geranyl acetate, neryl acetate, and α-terpinyl acetate that are important. Petitgrain oil also contains geraniol, nerol, α-terpineol, nerolidol, as well as the woody spathulenol and isospathulenol — both of which are constituents of clary sage oil. Interestingly, small amounts of high-impact compounds like the violet-smelling β-ionone and rose-smelling β-damascenone can be found in petitgrain oil. Certain aldehydes, present in minor quantities, also contribute to the character of petitgrain oil. Some aldehydes impart strong, exotic, spicy odours. 3-ethyl-benzaldehyde, on the other hand, possesses a benzaldehyde-like odour with a mimosa undertone. Yet, another aldehyde confers a fresh peel note. There is also a galbanum-reminiscent green note of 2-isopropyl-3-methoxypyrazine. And though extracted from a citrus plant, nootkatone and other typical components of citrus oils are not found in petitgrain oil. Such is the complexity of a deceptively simple perfumery material that is petitgrain oil.
Petitgrain in Perfumes
As with many citrus ingredients, petitgrain oil is classically related to the eau de cologne genre. For example, Original Eau de Cologne (Farina, 1709) by Johann Maria Farina contains 20% petitgrain oil. The classic 4711 Echt Kölnisch Wasser (Mülhens, 1792) by Wilhelm Mülhens features 11.3% petitgrain oil. However, petitgrain oil can also provide natural brightness to the aldehydic floral genre, and the iconic Chanel N°5 (1921) in the original formula is one such prime example that contains 1% petitgrain oil. Moreover, petitgrain oil is used to brighten oriental or floral compositions, but it is rarely dosed more than 2% in modern times. Such a relatively high dose of 2% is found in Habit Rouge (Guerlain, 1965), Eau Sauvage (Dior, 1966), and Eau d’Hadrien (Annick Goutal, 1993).
Beyond these, petitgrain oil is also used as a substitute for the more expensive neroli oil in functional products. This is because of its relatively inexpensive price and good performance even in bases such as air fresheners and soaps. Still, the high content of linalyl acetate makes petitgrain oil unstable in strong detergent.
Sources: biolandes.com, Scent and Chemistry The Molecular World of Odors
- Zarzo M.Sensors (Basel, Switzerland). What is a Fresh Scent in Perfumery? Perceptual Freshness is Correlated with Substantivity. 2013;13(1):463-483.