Why is the scent of osmanthus so difficult to replicate?

This autumn, I was wrapped tightly in the fragrance of osmanthus . The rich sweet aroma made me dizzy, so much so that I asked in my circle of friends: How can there be such a flower with such an unrestrained fragrance? !

But I am afraid that not many friends have the same trouble as me. After all, the scent of osmanthus is well-loved and has long been associated with the cooler wind and the Mid-Autumn moon. Not only have many brands launched osmanthus-scented perfumes and hand creams, but in recent years, coffee shops and dessert shops have also launched osmanthus-scented autumn limited editions.

In recent years, even coffee shops have been popularizing sprinkling a handful of osmanthus flowers on their lattes in autumn｜TuChong Creative

However, there is always controversy over whether these osmanthus-flavored products are osmanthus-flavored enough. Some osmanthus-flavored perfumes are evaluated as "having nothing to do with osmanthus." Even for the same product, different people may have different opinions on whether it is osmanthus-flavored enough. Why is it so difficult to make an osmanthus-flavored product that everyone can accept?

What kind of osmanthus are you talking about?

Osmanthus fragrans, formally known as "Osmanthus fragrans" in Chinese, has four common varieties: Jingui, Yingui, Dangui and Sijigui. Although there is no obvious difference in the fragrance composition of these four varieties, they are all mainly composed of linalool and its oxides, β-ionone, ocimene and γ-decanolide; however, the proportions of various aromatic components are different, which brings subtle differences to their taste.

Four species groups: Albus on the upper left is silver osmanthus, Aurantiacus on the upper right is red osmanthus, Luteus on the lower left is golden osmanthus, and Asiaticus on the lower right is four-season osmanthus; different species in the same species group may have slightly different flower colors｜Lipeng Wu, Junyi Liu, et al. doi.org/10.1016/j.foodchem.2021.131853

Whether in appearance or aroma, golden osmanthus and silver osmanthus are usually the most difficult to distinguish, while red osmanthus and four-season osmanthus rely on flower color and phenology to differentiate themselves from the others - the flowers of red osmanthus are orange, while four-season osmanthus, as its name suggests, blooms in all seasons. Perhaps because of other characteristics, the aroma of these two varieties is relatively not so strong, so they are not suitable for pickling osmanthus candy, soaking osmanthus oil, and making various osmanthus products. The high content of linalool in red osmanthus makes it smell sweeter ; the content of linalool oxide in four-season osmanthus is higher, with a sweet woody fragrance .

Both golden osmanthus and silver osmanthus bloom in the fall, and in addition to the deeper color of the golden osmanthus than the silver osmanthus, they also have subtle differences in fragrance. The silver osmanthus has a lighter and sweeter aroma due to its high content of ocimene, a substance with a floral and grassy aroma with a hint of neroli. The golden osmanthus has a richer, woody aroma due to its high content of beta-ionone.

Golden osmanthus has the strongest flavor | Tuchong Creative

Ionones all have a strong floral scent. In October, when the osmanthus flowers are in full bloom, the overly strong aroma that bothers me comes from the golden osmanthus. As for the "light" scent of the red osmanthus and the four-season osmanthus, it is also because the content of β-ionone in their aromatic components is low.

The rich aroma of osmanthus is not only determined by chemical components, but also affected by biological factors. As a qualified plant, the release of aromatic compounds in osmanthus is naturally regulated. Studies have shown that β, D-glucosidase can hydrolyze the precursors of the aroma of osmanthus flowers and release the potential aroma components in osmanthus flowers, which makes the aroma of osmanthus more intense, so much so that people feel bothered.

Where does the osmanthus scent you bought come from?

The reason why sweet-scented osmanthus products are not sweet-scented enough may be that the osmanthus they imitate is not the type of osmanthus you are most familiar with. However, the extraction method is likely to be to blame as different extraction methods can produce different sweet-scented osmanthus flavors.

Osmanthus tea and osmanthus cake can be directly added with dried osmanthus, but osmanthus fragrance and osmanthus hand cream need to extract the aromatic substances in osmanthus.

Common osmanthus products, such as osmanthus extract and osmanthus absolute oil, are special products of China. Osmanthus hair oil and various osmanthus fragrances mostly rely on the reprocessing of osmanthus absolute oil.

Osmanthus extract is made from salted osmanthus. After desalting and dehydration, it is extracted with petroleum ether. The extract is evaporated and concentrated to recover the solvent. If the osmanthus extract is further dissolved in ethanol with slight heat, solid impurities are filtered out after cooling, and ethanol is recovered by vacuum distillation, osmanthus absolute oil is obtained. The main fragrance components in osmanthus extract are linalool oxide, p-methoxyphenylethanol, dihydro-β-ionone, β-ionol and phenylethanol, etc., and the same is true for osmanthus absolute oil.

Another common extraction method is distillation extraction, which can produce osmanthus essential oil and by-product osmanthus hydrosol . Their main aroma components are linalool and its oxides, γ-decanoic acid lactone, β-ionone, geraniol, etc.

As osmanthus fragrances have become more and more popular in recent years, the simulation of the fragrance will become more and more accurate｜Pixabay

The main components of the top notes of osmanthus are monoterpenoids, and there are quite a lot of low-boiling oxygen-containing compounds. Therefore, when we approach a living osmanthus tree, the first breath of natural fragrance we inhale is balanced, mild, sweet and pleasant, but the complex extraction method will lose some temperature-sensitive components in the natural fragrance.

According to literature descriptions, there are currently about 120 aromatic compounds that can be detected and identified in fresh osmanthus petals, but the aromatic compounds in these osmanthus products are greatly reduced - there are about 60 kinds of aromatic compounds in osmanthus extract, only 46 kinds of aromatic compounds in osmanthus pure water, and only more than 30 kinds of aromatic compounds in osmanthus absolute oil.

At the same time, osmanthus has so many aromatic compounds that it is not possible to completely simulate the fragrance of osmanthus by artificial synthesis. However, as the fragrance of osmanthus has become more and more popular in recent years, the extraction and synthesis processes should also improve accordingly. Of course, purification is not all bad - although purification will lead to the loss of aromatic compounds, it also makes the fragrance rich and long-lasting , easy to preserve and memorable, just like a yellowed old photo.

This laurel is not that laurel

Speaking of "Osmanthus", what confuses people are not only the four varieties of Osmanthus fragrans, but also the osmanthus of the Lauraceae family.

According to some scholars, the ancients confused the cinnamon of Lauraceae with the cinnamon of Oleaceae for a long time. For example, in the sentence "堤桂酒兮椒浆", "桂" is the opposite of "椒", which is a spice with a spicy aroma, so it is more likely to refer to the cinnamon of Lauraceae.

Cinnamon from Lauraceae｜Forest and Kim Starr

In fact, everyone is familiar with the cinnamon of the Lauraceae family. Spices such as cinnamon bark, cassia bark, and cinnamon are all in this category.

Cinnamon (Cinnamomum cassia) is made into spices and essential oils because of its special aroma. Cinnamon bark is dried and becomes cinnamon bark . Its main aromatic components include cinnamaldehyde, γ-pinene, α-selinene, etc. Cinnamaldehyde has a spicy smell, while γ-pinene and α-selinene have citrus and sweet smells and clove and earthy smells, respectively. Cinnamon oil extracted from cinnamon bark, branches and leaves has cinnamaldehyde, α-pinene, etc. as the main aromatic components. The smell of α-pinene is sweeter and closer to woody fragrance. The combination of the two creates the special aroma of cinnamon, which is spicy, sweet, mellow and warm. I believe everyone has seen it when stewing meat.

Cinnamon, thick | Yakeu Woangibar 3005 / Wikimedia Commons

The "cinnamon" commonly seen in desserts and fragrances is Ceylon cinnamon (C. verum), whose main fragrance components are cinnamaldehyde, eugenol, cinnamyl acetate, etc. Eugenol has a mild spicy aroma, and cinnamyl acetate has a mild floral and peppery aroma. The cinnamaldehyde content in Ceylon cinnamon is slightly lower, so the aroma is sweet and rich, and the spicy feeling is reduced, which is more suitable for various desserts . If you really can't imagine the aroma of cinnamon, Starbucks has cinnamon powder, and it's not a crime to smell it lightly.

Ceylon cinnamon bark, powder, and dried flowers | Simon A. Eugster / Wikimedia Commons

Essential oil extracted from Ceylon cinnamon leaves also has warm floral and fruity aromas. Some big-name perfumes, such as Gucci's Alchemist Garden series Nightfall and Serge Lutens' Five O'Clock Ginger, are dominated by cinnamon scents. The famous Serge Lutens's Forest Charm also has the scent of cinnamon. In addition, cinnamon is often seen in fougere notes, food notes, and fragrances that focus on spicy, sweet, and warm fragrances.

But as I write this, I am thinking that when we think of the taste of cinnamon, we often associate it with hot and fragrant stew. The fragrance itself is often difficult to separate from the scene, which may be the reason why we feel that various osmanthus-flavored products are like osmanthus but not osmanthus enough - the missing charm may be autumn itself.

Perfumes featuring cinnamon remind people of warm things, while perfumes featuring osmanthus may essentially be about putting autumn into a bottle and preserving it forever｜Laitr Keiows / Wikimedia Commons

Author: 媗媗

Editor: Mai Mai

Cover image source: Laitr Keiows / Wikimedia Commons

This article comes from GuokrNature (ID: GuokrNature)