Abstract:In this study, pomelo peel essential oil was prepared by cold pressing, steam distillation and mechanical dermabrasion. The effects of direct injection and solid phase microextraction (SPME) on the type and amount of volatile components of pomelo peel essential oil were compared. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were applied to analyze the volatile components in essential oils extracted from the three methods and identify the characteristic volatile compounds. The results showed that totally 69 compounds were identified by the approach involving direct injection combined with GC-MS, and 51 compounds by SPME combined with GC-MS, with the direct injection approach showing the volatile profile of essential oil more comprehensively than SPME. For the volatile profiles obtained by the direct injection method, PCA analysis can distinguish the three kinds of pomelo peel essential oils with those derived from cold pressing and mechanical dermabrasion being more similar. PLS-DA analysis revealed that the characteristic volatile components in the three essential oils can be distinguished: Sabinene, D-limonene, α-terpineol, β-myrcene, α-pinene,and 4-terpineol in cold pressed oil; Linalool, (R)-limonene oxide and 8,9-dihydroneisoxylene in steam distillation oil; Nootkatone, n-palmitic acid, and (Z,Z)-9,12-octadienoic acid in dermabrasion oil. Among them, the characteristic volatile compound limonene oxide (5.19%) in steam distillation oil exhibited an irritating odor. The volatile components with a retention index greater than 2000 was higher (4.61%) in dermabrasion oil, which affected the clarity and stability of essential oils. Based on the above analyses, the quality of the pomelo peel oil prepared by cold pressing was better.
