CIESC Journal ›› 2012, Vol. 63 ›› Issue (3): 826-833.DOI: 10.3969/j.issn.0438-1157.2012.03.022

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Preparation and extraction of onion essential oil by ionic liquid and ultrasound-microwave-assisted method

CAO Hong1,DUAN Haiyan1,LI Chun1,2,XIN Na1,LI Jun1,LI Bingqi1   

  • Received:2011-08-09 Online:2012-03-05 Published:2012-03-05

离子液体超声-微波协同制取洋葱精油

曹红1,段海燕1,李春1,2,辛娜1,李军1,李炳奇1   

  1. 1石河子大学化学化工学院,新疆兵团化工绿色过程重点实验室-省部共建国家重点实验室培育基地;2北京理工大学生命学院
  • 通讯作者: 曹红

Abstract: To improve enzyme catalytic efficiency, the ionic liquid/buffer biphasic system was used as bio-catalytic medium in catalytic hydrolysis of alliin to the sulfur-containing compounds by alliinase. The results showed that the enzyme activity was higher for 25% [BMIM]PF6/ buffer biphasic system than for pure buffer system but inhibited markedly by excess amount of [BMIM]PF6,and the thermal stability of the enzyme was enhanced. Using natural alliin as substrate,the Km of 0.591 mmol·L-1 and the Vmax of 0.316 mmol·L-1·min-1 were obtained for the enzyme catalytic reaction in [BMIM]PF6/buffer biphasic system,and the Vmax/Km ratio was about 2 fold of buffer monophasic system. In addition,in order to rising yield of essential oil,a combination technique of ionic liquid [BMIM]PF6,as bio-catalytic medium and extraction agent,and ultrasound-microwave-assisted was used for preparation and extraction of onion essential oil. The optimized conditions established were as follows:[BMIM]PF6 concentration 20%(vol),enzymatic time 2 h,ratio of raw material to liquid 1∶1.5,extraction temperature and time 25℃ and 50 s,and ultrasound-microwave power 150 W.Total 22 substances were identified in the onion essential oil prepared from fresh onion and 19 kinds of them sulfur-containing compounds by GC-MS analysis.To improve enzyme catalytic efficiency, the ionic liquid/buffer biphasic system was used as bio-catalytic medium in catalytic hydrolysis of alliin to the sulfur-containing compounds by alliinase. The results showed that the enzyme activity was higher for 25% [BMIM]PF6/ buffer biphasic system than for pure buffer system but inhibited markedly by excess amount of [BMIM]PF6,and the thermal stability of the enzyme was enhanced. Using natural alliin as substrate,the Km of 0.591 mmol·L-1 and the Vmax of 0.316 mmol·L-1·min-1 were obtained for the enzyme catalytic reaction in [BMIM]PF6/buffer biphasic system,and the Vmax/Km ratio was about 2 fold of buffer monophasic system. In addition,in order to rising yield of essential oil,a combination technique of ionic liquid [BMIM]PF6,as bio-catalytic medium and extraction agent,and ultrasound-microwave-assisted was used for preparation and extraction of onion essential oil. The optimized conditions established were as follows:[BMIM]PF6 concentration 20%(vol),enzymatic time 2 h,ratio of raw material to liquid 1∶1.5,extraction temperature and time 25℃ and 50 s,and ultrasound-microwave power 150 W.Total 22 substances were identified in the onion essential oil prepared from fresh onion and 19 kinds of them sulfur-containing compounds by GC-MS analysis.

Key words: ionic liquid, [BMIM]PF6, ultrasound-microwave-assisted extraction technique, alliinase, onion essential oil

摘要: 以离子液体[BMIM〖DK〗]PF6作为生物催化介质,结果显示洋葱蒜氨酸酶在含25%[BMIM]PF6催化体系中的活性比在纯缓冲液介质中明显要高,对高温变性作用的抵抗能力也相应增强,但若离子液体浓度过高会对酶催化作用的发挥产生阻碍。以洋葱蒜氨酸为底物,测得离子液体[BMIM]PF6/缓冲液两相体系中蒜氨酸酶的米氏常数为0.591 mmol·L-1,最大反应速率为0.316 mmol·L-1·min-1Vmax/Km约为缓冲液单相体系中的两倍。实验还尝试发挥疏水性离子液体[BMIM]PF6作为生物催化介质和萃取剂的双重功能,并将其与超声-微波协同萃取技术相结合应用于洋葱精油制取的酶解和萃取过程,明显提高了酶解效率和精油得率,将制得的精油经GC-MS分析,共鉴定出22种物质,其中19种为含硫化合物。

关键词: 离子液体, [BMIM]PF6, 超声-微波, 蒜氨酸酶, 洋葱精油

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