The yield and quality of gaharu oil (aquilaria malaccensis) extracted by three methods

Abstract

Gaharu (Aquilaria malaccensis) oil and resin are among the most valuable products from forest. The essential oil and resinous wood of gaharu are widely used for their aromatic, fumigator and medicinal properties. Currently, the main problems in the production of gaharu oil were the issues of the various extraction methods which were not uniform and the lack of establishment of gaharu standard to evaluate its quality. The prices as well as the quality of gaharu oil are arbitrarily determined by traders and clients due to no established standard that can be referred. Therefore, the aim of this research was to study the appropriate extraction methods for the production of gaharu oil. The work focused on the performance of three different extraction methods i.e. Soxhlet extraction, hydro distillation and Accelerated Solvent Extraction (ASE). The results showed that the yield of gaharu oil increased with the increasing of extraction temperature, duration and solvent volume. The ASE method yielded higher percentage (2.28% ± 0.02) of gaharu oil than Soxhlet extraction (1.67% ± 0.01) and hydro distillation (0.18% ± 0.01). Moreover, the colour of ASE oil at elevated temperature was dark brown in comparison to oil from Soxhlet (brownish) and hydro distillation (dark green). Analysis of chemical compounds of the oils extracted via different methods showed a similar pattern of chemical profile but significant difference in the percentage of specific chemical compounds. ASE method was selected for further study, hence the gaharu oil extracted via Soxhlet was used as benchmark in relation to the presence of all expected chemical compound detectable in the gaharu oil at appreciated percentage. ASE method was optimized at the extraction temperature of below 150 ˚C because increased extraction temperature promoted the degradation of chemical components in the gaharu oil. The optimal parameters of ASE (ASE OPT) were found to be at temperature of 141 ˚C, duration of 90 min, and solvent volume of 90%. The yield from ASE OPT was 1.74%. Gas chromatopgraphy-mass spectrometer (GC-MS) was used to identify the specific chemical compounds of ASE OPT gaharu oil. The data was highly comparable with Soxhlet extraction result in which the percentage of most of the chemical compounds were significantly higher in the ASE OPT oil i.e. 3phenyl-2-butanone (1.59%), α-agarofuran (0.97%), 10-epi-γ-eudesmol (10.20%) and agarospirol (6.72%) than Soxhlet extraction (0.25, 0.22, 0.72 and 5.49% respectively). However α-guaiene (2.64%) were found slightly lower in the ASE OPT gaharu oil compared to gaharu oil of Soxhlet extraction (2.83%). The ASE OPT gaharu oil was categorized under viscous essential oil and it also tends to have heavier aromatic compounds.