For this journal piece we wanted to delve a little deeper into the world of Aquilaria sinensis (agarwood or oud) extraction on a commercial scale and understand more about the processes involved.
We are delighted to share a discussion with our friend and collaborator Jeff Zeng from Yuzhi Oud. Yuzhi Oud have planted over 400,000 Aquilaria trees over 350 hectares in Hainan and Guangdong in China with the support of over 100 local farmers and the collaboration of local families and communities. Yuzhi are championing the sustainable production of oud oil on a commercial scale.
Jeff can you please tell us a little more about Yuzhi Oud, when did the project start and why?
Yuzhi Oud is a family oud business started by my father. He would often go to Hong Kong, Laos, Malaysia, Singapore for his work in international trade. During the time he fell in love with the scents of oud, and made friends with many oud lovers from around the world. He then started to collect wild oud from Laos, Vietnam, Malaysia and Japan.
In the 1980s, he soon realised that the extraction and use of oud was not sustainable, so he decided to dedicate his time towards protecting wild oud and developing sustainable methods to produce agarwood extracts. He started his aquilaria tree plantation project in Hainan and Guangdong and set up a distillation facility dedicated to oud oil over 20 years ago.
I grew up with the scent of oud and have been fond of this smell since I was a child, I have an indissoluble relationship with it. I am on a mission, I want to introduce the beauty of Chinese oud to friends all over the world.
What makes Hainan and Guangdong so good for growing and extracting Aquilaria?
Hainan and Guangdong are provinces in south China.
The most suitable environment for the growth of Aquilaria Trees is between 100 meters and 600 meters above sea level, but we find the higher the altitude, the purer the aroma of the Aquilaria trees. The middle and low altitude Aquilaria extracts tend to be thicker and turbid. For example, the aroma of Aquilaria tree extracts produced at higher altitude regions such as Hainan tend to be very pure and highly fragrant.
In the mountains and hills to the south in Guangdong Province there are wild Aquilaria sinensis trees, most of which grow and flourish at around 500m above sea level.
Aquilaria sinensis loves high temperature environments, with a preference for an annual average temperature of above 20 ℃ and a minimum temperature of 3 ℃ in winter. The trees can however adapt to short-term low temperature frost.
The fragrant Aquilaria oleoresin is formed in the heartwood as a defence mechanism to many types of bacteria, the types of bacterias involved depends on geography, climate, age of trees, injury, whether it has been intentionally inoculated.
At Yuzhi Oud you are inoculating, I really want to dig deeper into the inoculation process can you tell us more on your processes?
Yes the highly prized fragrant resin is produced when the tree is injured and the heartwood is infected with bacteria, this leads to the formation of the prized aroma molecules, a mixture of organic compounds and wood fibres, its chemical precipitates are mainly sesquiterpenoids and chromones.
We use a few different methods of inoculation highlighted below
We usually choose 8-10-year-old standing trees with a diameter of around 30 cm. We make cuts 1.5-2 meters from the ground. The distance between cuts are 30-40 cm, and the wound depth is 3-4 cm. After a period of time, the xylem near the wound will secrete resinous substances that gradually turn black and brown after a few years. The longer the resin is left, the better.
Semi dry method
We make incisions in the tree 1 to 2 meters above the base, the depth should be between one-third and one-half of the thickness of the tree. We then create similar incisions in the same direction at different heights at intervals of between 30 to 40 cm. After several years, the resin can be taken from the wound, again the older the better.
We drill several square holes with depth of 2-3cm, width of 3-4cm and height of 3-4cm in to the trunk 1-3m above the ground, and then we seal with mud. The xylem near the holes gradually secretes resin, and after a few years it matures and is ready to be collected. In general, this method is faster and preferred.
Organic inoculating bacteria to form fragrance
We have an expert team who worked with the National Academy of Sciences to develop a proprietary blend of agarwood inoculating bacteria. Sorry we cannot share what exactly is in there, thats a secret.
On the windward and sunny side, from the same side of the trunk from top to bottom, every 40-50 cm, we use a saw or chisel to open the incense gate in the direction perpendicular to the trunk. The depth is about 1 / 3 of the trunk, and the width of the mouth is 1-2 cm. If the weather is dry, you can wet the wound with cold water, then fill the incense door with the bacteria blend. We wrap and seal the gate to prevent the further infection of miscellaneous bacteria, the infestation of insects and ants, and maintain the moisture required by the bacteria to work effectively.
How long does this process take from inoculation to the tree producing the resin? Then when are the inoculated trees harvested?
It depends some trees take 2-3 years, others 5-10 years. The trees are normally 15-20 years of age prior to inoculation, we then wait for several more years when there is a certain amount of resin and then we harvest. So the whole process from growth to harvest to extraction can take between 15-35 years. We then grind the infected heartwood prior to extraction and then extract.
Benefits of using Supercritical fluid CO2 extraction
It can be extracted at near room temperature (35-40 ℃), effectively preventing the oxidation and escape of thermo sensitive substances. Therefore, all the components in the wood are preserved in the extract, and the substances with high boiling point, low volatility and easy pyrolysis can be extracted below their boiling point temperature.
SFE is a clean extraction method, because there is no organic solvent in the whole process, so there is no residual solvent in the extract. At the same time, it also prevents the toxicity of the extraction process to human body and environmental pollution, and is 100% natural.
SFE has high extraction efficiency with less energy consumption, its better for the environment and less expensive (once you have invested in the equipment).
CO2 is an inert gas and non combustible gas, its tasteless, odourless and toxicity and safety is good.
CO2 is inexpensive, high purity, easy to obtain, and recycled in the production process, so it is more cost effective.
Both pressure and temperature can be used to regulate the extraction process, so we can get real consistency with our extracts. The purpose of extraction can be achieved by changing the temperature or pressure. When the pressure is fixed and the temperature is changed, the substance can be separated; On the contrary, the temperature is fixed and the pressure is reduced to separate the extract, so the process is simple and easy to master, and the extraction process is fast.
CO2 extraction produces clean, cost effective and sustainable agarwood extracts. We still extract by hydro distillation and it s great to be able to offer our clients the different expressions.
The popularity of oud continues to rise, can you tell us a little more on the future for Yuzhi Oud
The history of agarwood in China can be traced back to the Tang Dynasty (A.D.618-907). We have used agarwood since ancient times as a medicine, incense, religion, royal activities and so on. Through the propaganda of many experts, perfume brands and due to its dynamic scent more and more people are engaging with agarwood. Internationally, many people only know this fragrance from countries like Thailand, Vietnam, India but are not aware of the long history and relationship China has with these tree's. We really want to champion and celebrate Chinese agarwood production and introduce our work to new friends around the world.
We have formulated two products using Yuzhi Ouds CO2 extracted Aquilaria oils, our incredibly moisturising Agarwood & Labdanum cream and our nourishing Agarwood & Sandal Face Oil
Complex and dynamic this is a celebration of scents infused in a deeply moisturizing cream for face, hands and body. Our favourite aromatics have gone into one jar - an elegant and fragrant unfermented pure oud oil (agarwood) from sustainable agarwood forests in Hainan China in combination with sensuous Indonesian sandalwood; the finest aromatic Indian Ruh Khus (vetiver), deep resinous notes of labdanum resin and fresh Himalayan cedarwood. Ultrasonically emulsified and whipped into a base of hydrating argan and hemp seed oils, coconut oil and aloe vera, this is a cream like no other.
How best to enjoy
Massage into skin post washing or bathing
Aquilaria sinensis (Agarwood / Oud): We use a rich and highly fragrant sustainable supercritical CO2 extracted oil from the heartwood of Aquilaria sinensis trees from sustainable forests in Hainan & Guangdong, China. A total number of 400,000 Aquilaria trees have been planted over 350 hectares with the support of over 100 local farmers and the collaboration of local families and communities. For every tree harvested, 2 saplings are planted, the trees are rotated to infect and inoculate with bacteria, the response of the trees to inoculation is to produce a rich highly aromatic anti-bacterial resin. The inoculated trees are then harvested between 15-20 years old, processed and extracted for this stunning fragrance.
Santalum album (Sandalwood): Direct from our friends in Indonesia who are championing sustainability in sandalwood production across the country. With the unmistakable notes of aged Santalum album heartwood, this oil interacts deliciously on the skin - a truly wonderful expression of sandalwood.
This particular heartwood is over 30 years old and grown and harvested in Gunung kidul, Java Island, distilled by Didik Budy Andayani and produced in very limited quantities.
Ruh Khus (Vetiveria zizanoides): A phenomenal traditional hydro-distillation of wild-harvested vetiver rhizomes from one of India’s most celebrated distillers. The vetiver rhizomes were harvested and distilled between February – March 2020 in Hasayan and Kannauj in Uttar Pradesh. The oil of Ruh Khus is a startling emerald green due to its conversation with the copper still.
Cistus ladaniferus (labdanum): The bushy Cistus ladaniferus trees grow in the sun-drenched rocky terroir of the Isfahan Province near Kashan, Iran. Labdanum is a member of the rock rose family it produces a beguiling, pungent and highly aromatic resin that forms on the branches and buds of the young Cistus trees, this highly aromatic resin is collected by hand by the local communities before being cleaned and extracted.
Cedrus deodora (Himalayan Cedar): A sensual, woody balsamic oil produced by our friend Bharat in Himachal Pradesh, North India from sustainable cedar forests. Cedrus deodora is a cedar species native to the Himalayas, growing at altitudes of 1,650-2,400 metres. Steam distilled from the roots and stumps of mature cedar trees from 2019, each harvested tree is replaced with seeds to rejuvenate the cedarwood forests.
Aqua, Cannabis sativa oil, Argania spinosa oil, Cetearyl wheat straw glycosides and Cetearyl alcohol, Glycerin, Cocos nucifera, Aloe barbadensis, Aquilaria sinensis, Cistus ladaniferus, Vetiveria zizanoides, Santalum album, Cedrus deodora, Xanthan gum, Tocopherol, Sodium benzoate & Potassium sorbate. Naturally occurring Limonene, Linalool & Geraniol.