Great question @Rasoul. I’m afraid I can’t give you any hard facts, but thought I’d share my view on the matter because it can be quite a contentious issue - to science or not to science?
I’m of the old ‘small-leaf-big-leaf’ school. I don’t know much about linalool, mycrene or pinene, but that doesn’t mean I don’t know lavender relieves my headache, citrus uplifts, white bread gives me brain fog. And that’s how we approach distillation as well. Maroke + yield = nightmare, despite doing what current publications have offered to change the equation.
We once had a colleague draft a compilation of scientific findings on things like which species dominate where, which compounds dominate in which species, etc. We intended to publish it as an article, but ended not doing so because, well, it just looked like bad science for the most part.
For example, it’s even been posted on another forum with great authority how fermentation has been scientifically proven to increase the yield. Many distillers continue to soak their wood primarily based on this belief, not because they especially enjoy the barn. We’ve done side-by-side runs to check such claims (using different species and different setups) and found no difference, or even contradictory results. (That doesn’t mean fermentation doesn’t increase the yield, but as the saying goes: it depends…)
One guy I know, who often wonders about the way we do things, always says: '…but professor so-and-so from the university of such-and-such says you should do it this way.' Except, professor so-and-so clearly never had any hands-on experience.
A respected scientist used to write me with details debunking a great deal of the scientific details published by a respected member in the community, annoyed at how people could take it serious.
I’ve seen two people look at the same GCMS report and derive completely different interpretations from it.
For decades the Heart Foundation heavily endorsed trans fat while the US government blacklisted anything saturated.
I think we all remember the recent incident where they retested 100 scientific studies whose results have become accepted in the mainstream. Only 39 could be replicated. I’m pretty sure many if not most studies into agarwood will suffer a similar fate. It’s such a niche field of study, there’s hardly any incentive for throughly peer-reviewed, repeated studies. Not to mention, most of agarwood distillation has remained unchanged, so even existing studies about distillation have only looked at one or two kinds of traditional methods. I’m sure none of them have accounted for all the cold, hot, hybrid soaking going on these days.
A molecular analysis will no doubt be useful. If you find which terpenes acts how in which concentration will give you an indication of what to expect… given you also know how those interact with other factors. My mood’s been affected differently using oud from the same region. Some Indian ouds soothes my sleep, or at least relaxes the nerves. Others don’t. I’ve found some Hindi distillations as uplifting as the most playful Thai oils.
If you fry an orange, grind and dry lavender, crush cannabis, eat turmeric with garlic or black pepper, it all influences the way these substances get absorbed and processed… and how they make you feel. I guess it's the way with oud oils, where there are different temperatures involved, different interactions with different types of minerals at different intervals.
There’s no doubt that doing lab reports for each and every oil would be illuminating, but practically/financially it’s a challenge. And I’m not sure if it’ll really be worth it – I don’t foresee people looking to these reports for certain terpenes to help them decide which oils to get. Experience does the job well enough. Or, if distillers will choose to invest a lot of money to chase after certain compounds, only to discover that factor X flushed your expectations down the drain.
That doesn’t mean we haven’t pursued distillation scientifically. Of course, the blue-green aquatic notes in our New Guinea distills reflect a certain organic composition. We might not know what those opponents are called in biology class, but we know that gyrinops distilled in a unique way will get you that smell.
I know caffeine will usually mess with my sleep and make me grumpy soon after it made me feel great. But when you drink coffee infused with certain mushroom extracts, the comedown hardly ever hits; prepared a certain way with certain beans, I can pass out just like that. Some Thai oils are super playful and uplifting, but then you also get an oddball like Adikuto X which is all serious and mellow. The artist might not know the molecular makeup of the paint he loves to work with most - all he/she knows is that the viscosity is perfect, the hue just right. The greatest leather tanners don’t know exactly how hibiscus interacts with the hide, but they know which conditions affect the look and feel and if it’ll be suitable for bookbinding or not.
Taha has mentioned how some compounds are found more in certain species and I think he has based some of his distillations on that model, so here’s an instance of it being used towards a specific end - say, to capture more vanilla. And that’s great.
So, I’m not making a case against scientific research into agarwood here, but wanted to mention why we don’t rely much on what's currently available, even though some people seem to attach a greater degree of trust to a distillers who quote scientific literature to back up their claims.
The upshot: By the time scientific literature catches up, there probably won’t be enough of wood left to double test the findings with.