Gaharu bears a wide range of qualities. A grading system is being developed by the board of Indonesian Standarization System (Badan Standarisasi Nasional) for gaharu quality based on a set of characters. Today, aromatic sense and color are of the most important characters for grading gaharu quality. Currently, there are two methods frequently used for grading gaharu quality as follows:
To assess gaharu quality from the scent is a bit difficult, since there are many factors may inluence the quality of gaharu products, such as the species, georaphical location, habitat, microorganism and purity of the products. The age of infection may also influence both quantity and the quality of gaharu. Conventionally, the quality of gaharu is primarily determined from its scent, not the type of the wood. However, the pricing does not always follow and equal to the quality since the price is decided by both seller and buyer.
Other method to standarize the quality is based a image processing. Some researchs are being conducted to determine the quality of gaharu using image processing technique. Detail on the method can be downloaded here.
Using Z- score Technique
Classification of the quality of agarwood oils from Malaysia has been introduced using Z-score technique. Six agarwood oil samples named as MU, MUS, MN, MNS, R5 and HD are analyzed by GC-MS to examine their chemical profiles. The extraction showed that at least forty three volatile compounds are found. The Z-score technique is proposed to identify the significant chemical compounds of the agarwood oils. It is found that six chemical compounds are recognized. They are β-agarofuran, α-agarofuran, 10-epi-□-eudesmol, α-eudesmol, dihydrocollumellarin and □-eudesmol. These volatile compounds have different abundances pattern responsible to the different qualities of agarwood oil such as high and low. The Z-score applied in this study give a promising result in discriminating agarwood oil to high and low quality. It is important and useful in solving the grading agarwood oil system which is currently done manually. See more detail in “Classification of the quality of agarwood oils from Malaysia using Z-score technique” by Ismail, N. ; Fac. of Electr. Eng., UiTM Shah Alam, Shah Alam, Malaysia ; Rahiman, M.H.F. ; Taib, M.N. ; Ali, N.A.M.
The agarwood oil has been sold in various qualities based on its physical appearance such as color and odor. Consumer perception and high fixative properties also give marks in qualifying the agarwood oil thus affect its price in the market. However this conventional technique makes the price of agarwood oil fluctuates and not standardize in the market. A standard is needed to ensure that the agarwood oil can be qualified according to its chemical properties so that accuracy can be trusted . Therefore, as part of an on-going research in grading the agarwood oil quality, the application of ANN is proposed to analyze agarwood oil quality using its chemical profiles. The chemical profiles refer to the complex mixtures of sesquiterpene and its chromone derivatives in agarwood oil.
Artificial Neural Network (ANN)
An artifical neural network (ANN) has been modeled for the classification of Agarwood region. The target regions were from Melaka, Pagoh, Super Pagoh, Ulu Tembeling and Indonesia. The data analysis using Principal Component Analysis (PCA) was done to find significant input selection from 32 sensors of the E-nose and to recognize pattern variations from different number of Agarwood samples as inputs to ANN training. The network developed based on three layers feed forward network and the back propagation learning algorithm was used in executing the network training. Five input neurons, two hidden layer sizes and one output neurons were found to be the optimized combination for the network. The experimental results reveal that the proposed method is effective and significant to the classification of Agarwood region. See detail in “Classification of Agarwood using ANN M. S. Najib, N. A. Mohd Ali, M. N. Mat Arip, M. Abd Jalil and M. N. Taib, Member, IEEE”
Grading of Gaharu Quality in Trade
Gaharu is known in various product, its product possess different characteristics. Therefore, the product is classified according to various grading systems that may differ to each traded product and the country. The grade of gaharu, and also the its derivatives, such as oil is determined by many factors including the country; the fragrance strength and longevity; wood density; product purity; resin content; colour; and size or quantitiy of the product.
The type and number of gaharu grades vary widely from country to country. Flakes or chips may be devided into three to five grades (Singapore). Each grade may have different chemical components and portion. Each consumer has different priority for assessing the quality of gaharu, which is related to its intended use, such as fragrance (Middle East consumers), odors which is used for perfumery (India), composition of resinous materials (Consumers from Taiwan), dryness and sortiment of chips (Indonesia), water sinking-floating and so on. Gaharu oil is mostly graded based on the quality of raw materials, the method of distillation and the skill used in processing. Purity is also used, eventhough it is still impossible to find high purity gaharu oil. Traders have quoted prices for grade one -pure agarwood oil as high as USD30 000/kg, such oil only being made to order. Grade-two oil costs approximately USD15 000/kg, but generally oil prices are between USD5000/kg and USD10 000/kg. Few traders nowadays, if any, can assess oil quality or purity, but it is hardly possible to have consistent results between oil batches. Only one large gaharu-trading company appears to be capable of testing oil purity using gas chromatography and high performance liquid chromatography.