Method for evaluation of agarwood essential oil quality
….. at the end of this Ouducation … at least you should be able to determine an appropriate man-made inoculant confidently ….
Conventionally, the agarwood oil was graded according to its colour, aroma and fixative based on human’s sense. However, it was difficult to standardise it’s quality from the aroma due to human nose cannot smell many samples continuously. There were also limitation in terms of subjectivity, poor reproducibility and time consumption.
Different country has its own way to grade/classify the agarwood oil. Agarwood oil is traded on the basis of qualities; high and low but there are some countries prefer grades. In Malaysia, agarwood oil is classified according to the grade of A, B, C and D. In India, they use grades too; A, B, C and D but were based on the color of agarwood oil. In Japan, agarwood oil is categorized as high and low quality where Kanankoh is the highest quality and Jinkoh is low quality. Therefore, no standard available for this highly price oil.
GC-MS analysis is one of the common laboratory technique carried out to grade agarwood oil by analysing the chemical profiles of the oil. After making GC-MS analysis on Agarwood essential oil obtained from hydrodistillation we have a data set of volatile organic compounds (VOCs). From VOCs we should pay attention to the so-called Key compounds and Dominant compounds which are defined as follows:
Key compound is the term that includes:
Sesquiterpenes (having a common molecular formula C15H24)
Sesquiterpenoids (having a common molecular formula C15H24O)
Sesquiterpene alcohols (having a common molecular formula C15H26O)
in which Sesquiterpenoids and Sesquiterpene alcohols are called Dominant compound.
Practical experiences: The higher content of dominant compound ( b + c ) the better aromatic scent and therapeutic effects of agarwood essential oil. In other words, key compouds and dominant compounds are very important for controlling the odor of fragrances and show a wide range of biological activities (antibacterial, antivirus, antifungal, immune inhibition, plant growth regulation, benefits to health,…).
Let a be the content of all Sesquiterpenes (molecular formula C15H24)
Let b be the content of all Sesquiterpenoids (molecular formula C15H24O)
Let c be the content of all Sesquiterpene alcohols (molecular formula C15H26O)
Let d be the total content of all volatile aromatic compounds and their derivatives
Let e be the total content of all fatty acids and their derivatives
Let f be the total content of all allergens
Let g be the total content of all toxins
Let S be the total content of all VOCs listed in the GC-MS Test Report
Definition of x and y:
x=a + b + c ; y = x/a
S ≥ 70%
d ≥ 2%
e ≤ 15%
f = g = 0
An agarwood essential oil is evaluated in very good quality if: x ≥ 65% and y ≥ 6.25,
the bigger the value x and y the better quality of agarwood essential oil.
Note 1: If we want to set up a possible compromise between x and y then we should choose two positive numbers ℽ and µ, (ℽ+ µ= 1), for forming the function z = ℽ* x + µ*y. So, the bigger z the better quality of agarwood essential oil.
Note 2: Easily seen y = 1 + α in which α was mentioned in http://springjournals.net/full-articles/springjournals.netijarrarti…
So if y ≥ 6.25 then α ≥ 5.25
List of C15H24, their common name Sesquiterpene …”click here”
List of C15H24O, their common name Sesquiterpenoids …”click here”
List of C15H26O, their common name Sesquiterpene alcohols …”click here“
Realizing the important parameters in determine quality of agarwood oil, and the man-made inoculant impacts directly to the quality of cultivated agarwood. Agarwood cultivators are advised to verify if the so-called inoculant ….. provided by the service provider will fulfill the above-mentioned requirements??
Case study … example of good quality cultivated oil
Another interesting topic to explore … from the GC-MS data in Master’s thesis of Dang Nam Nam submitted in 2009 at the University of Natural Sciences (National University of HCMC) (see Evolution trend of chemical compounds in agarwood inducement process), we find:
- The Key compounds have an increase in the agglutinating time
- Fatty acids and aldehydes have a decrease in the amount of agglutination
So, quality of cultivated agarwood oil can be improved by prolong the inducement time prior to harvest, lessor contents of Volatile Fatty Acids, lessor the pungent smell of oil.OMG !! You may wonder, what causes the Key compound to reduce? It sounds ridiculous. As a thumb of rule, longer the better to keep the agarwood in the living trees. I do believe some trees are healthy enough to undergo “RECOVERY”, where the wounded tissue reinstates by itself inevitably.
…when external attack is introduced into tree’s tissue, it provides stress to the tree tissue, causing a long period of WAR between tree’s defence mechanism and stress in the wounded tissue. Formation of agarwood is a process in nature through the dynamic interaction of trees and continuous stress. Layer of resinous wood is formed gradually, and this agarwood formation becomes thicker if PERFECT environment is matched. If the tree is very healthy, where the TUG-of-WAR is won by the tree’s defence mechanism, than most probably the treated tissue will end up in white tissue, where the wounded tissue has recovered. On the other hand, if the treated tree is rather weak, external stress may seriously damage to the said tree, even causing fatality…
My humble request to local inoculant service provider, pls furnish your GC-MS data to your customer, your data will speak for the inoculant. GC-MS report is NOT a private-and-confidential data, it is a powerful tool to promote your inoculant. A responsible inoculant service provider will be very proud and keen to present you the report instead of singing you the grandma story, “this la , that la, i show to my existing customers only la” … which i should bless him “Bakayaro”. If you are NOT the sleeping consumers, than the possible reasons by them, could be …
- don’t know what his inoculant is doing, as long as the result is black in color
- his inoculant is simply a scrap, just to get profit by selling them
- new inoculant service provider without proven sale in bulk
In Malaysia, some of them possess good inoculant, some of them NOT, “click here to explore”
Source : Vietnamese Agarwood Products