Khmer agarwood identification technology: from sensory evaluation to precise identification of molecular fingerprints

Khmer agarwood, due to its unique origin and excellent quality, has a market price 2-3 times higher than ordinary agarwood. However, the proliferation of fake and substandard products (such as oil soaked with white wood incense, artificial synthetic essence) has seriously damaged the rights and interests of consumers. How to achieve precise identification through technological means has become an urgent problem to be solved in the industry. This article analyzes the technical system of identifying Cambodian agarwood from three aspects: sensory evaluation, chemical analysis, and genetic testing.

1、 Sensory Evaluation: The Scientification of Traditional Experience

Sensory evaluation is the foundation of agarwood identification, and the quality is preliminarily judged through the four step method of "looking, smelling, asking, and cutting":

Observation: Observe the color and texture of agarwood. Khmer agarwood is mainly dark brown or black in color, with evenly distributed oil and texture in the form of "oil lines" or "patches".

Smell: Smell and distinguish the layers of fragrance. The aroma of Khmer agarwood is unique. The top note is sweet honey, the middle note is mellow frankincense, and the end note is slightly floral and fruity, and the aroma lasts for more than 8 hours after combustion.

Question: Inquire about the place of origin and the method of aroma production. Wild Cambodian agarwood has a longer growth cycle and a more complex aroma; Artificial fragrance results in a more monotonous aroma.

Cut: Touch texture and density. Khmer agarwood has a high oil content and a heavy texture (density>0.8g/cm 3), and sinks immediately upon entering water.

However, sensory evaluation relies on expert experience and is highly subjective. For standardization, the industry has formulated the "Sensory Evaluation Standards for Agarwood" (GB/T 39014-2020), which divides the aroma into five levels: "clear, sweet, cool, mellow, and strong", and quantifies the fragrance retention time and density indicators.

2、 Chemical analysis: from component fingerprinting to traceability identification

Chemical analysis achieves precise identification and origin tracing by detecting characteristic components in agarwood

Gas chromatography-mass spectrometry (GC-MS)

Analyzing the components of the volatile oil in agarwood, the characteristic components of Cambodian agarwood are β - agarfuran (content>15%), chromogenic ketones (such as 6-methoxy-2- (2-phenylethyl) chromone), and aromatic compounds (such as benzoic acid and cinnamic acid). By comparing the component spectra, it is possible to distinguish Cambodian agarwood from agarwood from other origins.

High performance liquid chromatography (HPLC)

Detecting non-volatile components (such as flavonoids and polysaccharides), the content of flavonoids such as quercetin and kaempferol in Cambodian agarwood is significantly higher than in other production areas, and can be used as a marker for production areas.

Stable Isotope Ratio Analysis (IRMS)

By detecting the isotopic ratios of carbon (δ 13 C), hydrogen (δ 2 H), and oxygen (δ 1⁸ O), combined with climate data from the production area, the growth environment of agarwood can be traced. For example, the δ 1 3 C value range of Cambodian agarwood is -28 ‰ to -26 ‰, which is clearly distinguished from other production areas.

3、 Genetic testing: from species identification to individual tracing

Genetic testing technology provides molecular level evidence for the identification of agarwood:

species identification

PCR amplification of the ITS sequence (ribosomal transcriptional spacer) of Aquilaria crassna was performed, and the gene database was compared to confirm whether it is Aquilaria crassna. This method can distinguish closely related species (such as Aquilaria malaccense) with an accuracy of 99%.

Individual traceability

Using single nucleotide polymorphism (SNP) markers to establish a "genetic identity card" for Cambodian agarwood trees. For example, the Cambodian Ministry of Agriculture, Forestry and Fisheries has established SNP files for 1000 wild agarwood trees, which can trace the origin and fragrance history of individual agarwood trees.

Research on the mechanism of fragrance formation

Through transcriptome sequencing analysis of gene expression changes before and after fruiting, it was found that the expression level of agarwood alcohol synthase (ASS) gene in Khmer agarwood tree was three times higher than that in other varieties, explaining the molecular basis of its high oil content.

4、 Technology Fusion and Future Directions

In the future, agarwood identification will develop towards "multi technology integration" and "portability":

Portable detection equipment: Develop handheld identification devices based on near-infrared spectroscopy (NIR) or Raman spectroscopy to achieve rapid on-site screening (results within 30 seconds).

Blockchain traceability system: By combining chemical analysis and genetic data, a platform for tracing the entire lifecycle of agarwood is established. Consumers can scan the code to view information such as origin, fragrance production method, and testing reports.

AI assisted identification: Train deep learning models to automatically identify the origin and quality level of agarwood by analyzing images and spectral data, reducing human error.