To reveal the extraction regularity of volatile oil from galangal by GC-MS analysis. The volatile oil in galangal was extracted by steam distillation. The extract was collected every 30 min, the oil part and the water part were separated. GC-MS was used to analyze the extraction liquid collected at different time periods. A total of 140 volatile components were obtained by GC-MS analysis. Among them, the main components were eucalyptus oil alcohol, alpha-pine oil alcohol and 4-terpene alcohol; 22 special components were dissolved in water, 77 special components were dissolved in oil and 41 components were dissolved in both oil and water. With the increase of specific components in water, the content of Eucalyptus in water increased in a linear manner. The increase of eucalyptus oil further promoted the dissolution or dispersion of alpha PN in water, and the change of specific components in oil was positively correlated with the content of Eucalyptus and alpha-terpilenol in oil. The results of principal component analysis show that the physical and chemical properties of the compounds were important factors affecting the distribution of components. PC1 (molecular weight, melting point, boiling point positive correlation), PC2 (negative correlation of refractive index) and PC3 (positive correlation of water solubility) were the main components that lead to the differences in composition distribution. The process of extracting volatile oil from galangal through steam distillation was affected by the physical and chemical properties of volatile components. Some components were specifically distributed in the fragrance and volatile oil system. The endemic components of aromatic water increased the content of the main components in the water system, which may lead to the "emulsification", reduction of the yield and low quality of the volatile oil.
Keywords: GC-MS; double internal standard method; extraction kinetics; galangal; volatile components.
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