| Litsea cubeba is known as Litsea,pheasant pepper,cubeb,etc.,widely distributed in the south of the Yangtze River region,such as Sichuan,Hunan,Fujian,Guangxi.Cubeba's whole plant contains essential oils.Under normal circumstances,Litsea cubeba oil is oil that extract from cubeba fruit.Litsea cubeba oil is a complex composition natural spices,Citral which is the main component,the content is generally between 60%to 80%,some up to 90%,its content varies with different origin,harvest,etc.Citral content is an important index to assess Litsea cubeba oil quality,citral content which is more than 97%was designated as the primary Litsea cubeba oil and available for export.Therefore,prospects of researching the extraction of high-quality citral from Litsea cubeba oil are very bright.Conventional method of extracting oil from cubeba citral are mainly steam distillation,chemical,vacuum distillation method,microwave extraction method,etc.With the development of technology in recent years,molecular distillation method is widely used in the purification of citral,compared with traditional methods,more and more reseatchers and producers paid attention to the latter because of extraction of high purity and extract citral quality advantages.In this paper,Litsea cubeba oil citral were isolated and purified by molecular distillation method,to provide a basis for industrial production,and we studied Litsea cubeba oil adulteration that appeared in current market to obtain identify methods.The main research contents are as follows:1.Litsea cubeba oil's component and component's content from Guangxi?Jiangxi?Fujian?and Hunan4 different areas were analyzed by GC-MS.It was found that four components of orngin Litsea cubeba oil varies,and the content of the same composition are also differences.Components that cubeba oil from 4 rigion are:limonene,terpinene,terpinolene,neral and geranial.2.Taking the Litsea cubeba oil of content of 80.9%citral as the research object,this experiment explored the effect of distillation temperature,distillation pressure and material flow on citral purity and the yield rate molecular distillation technology by single factor experiment firstly.On the basis,the experiment applied Lg(34)orthogonal test with the comprehensive weight score of citral content and yield rate as the indicators to determine the optimal combination of three factors,providing the basis for industrialized production and purification of high quality of citral from Litsea cubeba oil.The heavy constituent residue fractionation of Litsea cubeba oil was analyzed by gas chromatography-mass spectrometry system(GC-MS)using vanillin as an internal standard to determined quantity of citral.The experimental results showed that the optimum conditions was 400r/min scraping membrane speed,12-C cooling water temperature,55 °C distillation temperature,0.18kPa distillation pressure,15mL/min material flow with 1 L inventory.Under this condition,the purity of citral was 98%and the yield rate was 77.2%.The pilot test verified that this optimum conditions can be applied to industrial production.In order to further improve the quality of citral,we have made secondary molecular distillation.The distillation temperature is made variable single factor test,when the distillation pressure was finally determined 0.10kPa,feed rate of 15ml/min,the distillation pressure is 54 ? are the best conditions for the second molecular distillation.The purity of citral was 99.77%and the yield rate was 82.31%,citral overall yield was 63.8%by twice molecular distillation.3.We proposeda volatile oil extractor extraction,three GC-MS detection method and citral internal standard method to identify adulteration method focusing on several common cubeba oil adulteration phenomenon.After experimental verification,these methods can be effectively incorporated into the identification of non-volatile oil,volatile oil mixed with other,alternative synthetic citral,incorporation of synthetic citral cubeba oil adulteration. |
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