Author photo: Robert Taylor

Bitter orange

The bitter orange tree, Citrus aurantium subspecies amara, has been cultivated for its fragrance products for many years – as we have already learned how its blossoms yield neroli, the leaves and twigs yield petitgrain (meaning ‘little seed; look for the suffix ‘fol.’ to indicate that it is derived from leaves), also an important constituent of colognes, and the small fruits (suffix ‘fruct.’) yield bitter orange oil from their peel.

These fruits have a long history of culinary and medicinal uses. The liqueur, Curacao, is flavoured with the unripe fruits. The tree is native to Asia; and so its flowers and fruits form part of Oriental medicine – mainly as remedies for the myriad of disorders of the digestive system, as a cardiac tonic and for anxiety.

So, unlike the other aromatics in this short series, we turn exclusively to perfumery to discover bitter orange’s tradition of use. The citrus oils are some of the most volatile of raw materials of perfumery – they form the top notes – the ones that reach the nose first. Bitter orange oil has indeed a citrus odour, but in contrast with its close relation sweet orange, it is subtle, fresh, with a fairly tenacious floral undertone, and is considered by artisan perfumers to be more interesting. In perfumery, bitter orange is used in eaux de cologne (like its close botanical relatives neroli and petitgrain), but it is also is important in many other categories of fragrance. It gives a light, green-floral citrus freshness to the top notes of a composition; however like all of the citrus oils, this is short-lived and rapidly disappears as the fragrance heart develops. The tenacity and persistence of the citrus oils is poor in contrast to most of the other natural aroma materials.

However, in aromatherapy this tenacity issue is much less of a problem. The carrier oil used for massage will help slow down the rapid evaporation of the citrus oil in the prescription, and the scent is strong enough to be noticeable when first presented to a client. There have been several studies investigating the impact of citrus scents on mood, and it could be reasonably assumed that some of the mood benefits identified would apply to bitter orange. Citrus peel oils can decrease autonomic nervous system arousal (characteristic of stress) and promote feelings of cheerfulness and vigour, so the use of citrus oils to alleviate depression and stress is now a well-established aromatherapy practice.

The only caution regarding bitter orange, and some other citrus oils, is that they are phototoxic. This means that they should not be applied to skin that will be exposed to ultraviolet (UV) light, because burning can result. Phototoxic compounds in citrus peel oils are present because they are obtained by an expression process (literally squeezing the volatile oil out of the peel) rather than distillation. These molecules are quite large in comparison to the small ones found in essential oils, and they are not volatile (that is, they don’t evaporate) so they cannot be distilled. The phototoxic molecules can also be absorbed in to the top layer of the skin, and stay there for a few hours. If the skin is then exposed to sunlight, the molecules can absorb the UV light and store it before releasing it into the skin in a quick burst. The IFRA (International Fragrance Research Association) issue safety guidelines regarding the levels of such oils in products; the maximum limit for bitter orange oil in fragrance is 1.4%, at time of writing.

When you smell bitter orange, the top notes will appear fast and fleeting – citrus zest first, then the green notes, the floral notes will appear, and the heart is sweeter and slightly fruity. It is difficult not to smile and feel more at ease when bitter orange starts to make its impact, frustration and anger can diminish, making space for clarity of thought and the energy for creativity and innovation, or simply leaving the negative behind and making a fresh start.

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