Study On Extraction And Component Of Oil From Seeds And Leaves Of Onion(Allium Cepa L.)

Onion(Allium cepa L.) is one of the most popular vegetables all over the world,and it is also used as a drug herb in Asia.The main biologically active things are sulfur-containing compounds in onion oil as known.Onion oil are all extracted from the bable by now,while onion-seeds and onion-leaves are not be researched now.In this dissertation supercritical carbon dioxide extraction(SFE),steam distillation(SD), and solvent extraction were used to extract onion oil from onion-seeds and onion-leaves respectively.The optimal parameters were studied and the compounds were identified by GC-MS.The results were summarized as follows:1,Methods for qualitative and quantitative analysis of onion-seeds oil by GC-MS and GC were established.Compounds in onion-seeds oil were successfully separated.And 16 compounds were identified of which the main compounds were 9,12-octadecadienoic, 9-octadecenoic acid and hexadecanoic acid.2,Methods for qualitative and quantitative analysis of onion-leaves oil by GC-MS and GC were established.Compounds in onion-leaves oil were successfully separated.And 24 compounds were identified of which 16 compounds were sulfur-containing compounds.3,The parameters of supercritical carbon dioxide extraction(SFE) for onion seeds oil were optimized.Effects of dehydration,particle size,extracting pressure,extracting time, extracting temperature and the volume of co-solvent on the yield of onion seeds oil were studied.The results of orthogonal experiment showed that the optimal parameters were particle size 0.45～0.90mm;extracting pressure 24.5MPa;extracting temperature 43.7℃; extracting time 72min.Under the above condition the yield of onion seeds oil reached 12.08%.The products had pleasant aroma characteristics of fresh onion seeds.4,The parameters of supercritical carbon dioxide extraction(SFE) for onion leaves oil were optimized.The results of orthogonal experiment showed that the optimal parameters were particle size 0.90～1.18mm;extracting pressure 27.5MPa;extracting temperature 37.35℃;extracting time 57.9min.Under the above condition the yield of onion leaves oil reached 3.30～3.42‰.The products had pleasant aroma characteristics of fresh onions.