Effects of Different Extraction Methods on the Composition and Properties of Jinggangshan Pomelo Peel Essential Oil

Taking Jinggangshan pomelo peel essential oil (JPPEO) as the research object, two methods of steam distillation and low-temperature continuous phase transition were used for extraction. Orthogonal test was used to study the effects of extraction temperature, extraction pressure and extraction time on the yield of essential oil of Jinggangshan pomelo peel. At the same time, the physicochemical properties and chemical composition of essential oil were analysed. The results showed that the optimum extraction process of essential oil extracted by low-temperature continuous phase transition（L-JPPEO）was obtained as follows: particle size 30 mesh, extraction temperature 55 ℃, extraction pressure 0.6 MPa, extraction time was 60 min, and the analysis temperature was 70 ℃. At this time, the extraction rate was 10.99‰, the yield of L-JPPEO was 2.88 times higher than that extracted by steam distillation (H-JPPEO). The physicochemical properties of the essential oil of JPPEO extracted by low-temperature continuous phase transition showed that the content of unsaturated fat acid was higher, the content of free fatty acid was lower, the content of esters was lower. FTIR identified L-JPPEO and H-JPPEO containing terpenes, alcohols, phenols, aldehydes and carbonyl compounds. GC-MS technology identified 23 and 32 compounds from H-JPPEO and L-JPPEO samples, respectively. Among which 15 compounds were detected in both essential oils, the relative content of D-limonene was the highest, the relative content in L-JPPEO was 4.75±0.16 μg/mL, while the relative content in H-JPPEO was 640.93±44.47 μg/mL. HS-GC-IMS identified 71 compounds from both extraction methods of essential oils. Compared with steam distillation, low-temperature continuous phase change extraction technology extracted more terpenes (45.75%), ketones (7.68%), esters (15.85%), and acids (5.62%).