洋葱精油的亚临界水提取

Subcritical Water Extraction of Onion Essential Oil

为获得提取洋葱精油的新技术，采用自行设计的适合工业化应用的2L亚临界水提取装置提取了具有岭南特色的红葱头精油，考察了提取方式、提取时间、温度、压力对洋葱精油的提取得率及含硫化合物含量的影响，并对液-液萃取中溶剂的种类和萃取次数进行了研究．所得洋葱精油亚临界水提取的最佳工艺条件为：静态提取，提取时间30min，压力5MPa，100～150℃的连续程序升温，石油醚为萃取溶剂，萃取2次；此条件下洋葱精油的得率为0．362％，含硫化合物含量为97．36g/kg．与传统水蒸气蒸馏法和超声波辅助提取法相比，亚临界水提取法具有提取时间短、效率高、能耗低、产品质量高等优点．所设计的2L亚临界水提取装置自动化程度高，操作简便．

In order to develop a new technology to extract onion essential oil, a 2-L equipment of subcritical water extraction （SWE） suitable for industrial production was designed and used to extract the essential oil from the red onion peculiar in Lingnan. The effects of extraction mode, extraction time, temperature and pressure on the yield and the sulphur compounds content were then analyzed, and different extraction solvents and extraction times were investigated in the liquid-liquid extraction procedure. The optimal conditions of subcritical water extraction of onion essential oil were finally determined as follows ： a static extraction at 5 MPa for 30min, with a sequential programed temperature increasing from 100 to 150℃, and with petroleum ether as the extraction solvent for two extractions successively. The results indicate that （ 1 ） in the optimal conditions, the extraction yield of onion essential oil and the content of sulphur compounds respectively reach 0. 362% and 97.36g/kg; （2） as compared with the conventional steam distillation and ultrasonic-assisted extraction, the subcritical water extraction costs less extraction time, and possesses high efficiency, low energy consumption and high product quality, etc. ; and （3） the designed 2-L equipment of SWE is highly automatic and is convenient to operate.