Measurement of Volatile Oil Content in Oleoresins by Gas Chromatography and Comparison to Conventional Steam Distillation
The steam distillation (DIST) method, a classical method for volatile oil extraction, has been known for being an adverse method. The process takes up to 6 or more hours and the results collected could have a relative standard deviation (RSD) up to 20 %. Consequently, a gas chromatography (GC) method was developed to replace the DIST method. The GC method was time efficient with a run time of 30 minutes and has a high precision with less than 4 % RSD. GC data were sampled and compared with pre-existing DIST data to find discrepancies in some sample results. The incongruent results were further analyzed with spiking experiments conducted on black pepper, garlic and sage. While no satisfactory explanation for the discrepancies between the two methods was found, the possibility of degradation was eliminated. Overall, GC produced comparable data to those of steam distillation and with the benefit of time efficiency and reproducibility, further research and development of the GC method to replace steam distillation is recommended.