| Cymbopogon citratus(DC.)Stapf contains rich oil,which main ingredients are citral(geranial and neral)and β-pinene.Cymbopogon citratus(DC.)Stapf oil is widely used in food additives,health products,cosmetics,perfumes,and other fields.With today increasing emphasis on food safety,natural food additives are more and more welcomed by people.Compared with conventional artificial chemical food additives,Cymbopogon citratus(DC.)Stapf extract is much safer,comfortable,and enjoy a promising future as a natural food additive.Aiming at the demand to develop and utilize Cymbopogon citratus(DC.)Stapf oil,the paper carried out exaction process of Cymbopogon citratus(DC.)Stapf oil and conducted research on the chemical composition of different growth stages and antimicrobial activity.The main results obtained are as follows:(1)The optimum conditions was studied to extract Cymbopogon citratus(DC.)Stapf oil by steam distillation.Cymbopogon citratus(DC.)Stapf was taken as raw materials and steam distillation was used to extract the essential oil of Cymbopogon citratus(DC.)Stapf.Single factor and orthogonal experiment used to explore the effect on the extraction rate from different parts,extraction time,solid-liquid radio and the addition quantity of NaCl,determining that the optimal distillation conditions were:extraction time 180 min,solid-liquid radio 1:45,9%of the NaCl addition.The Cymbopogon citratus(DC.)Stapf oil yielding rate under this condition was(2.51±0.03)%.(2)The chemical composition analysis of Cymbopogon citratus(DC.)Stapf essential oil in different growth stages conducted from May to November with seven sampling,once per month.Then the paper calculated the yielding rate through steam distillation extraction.The Cymbopogon citratus(DC.)Stapf grass oil and Cymbopogon citratus(DC.)Stapf stems oil reached the highest yield in July,which were(2.51±0.03)%and(1.23±0.06)%respectively,the lowest yielding rate was in November.The research used gas chromatography-mass spectrometry(GC-MS)qualitative to analyze its chemical composition.The main composition of Cymbopogon citratus(DC.)Stapf essential oil was citral(geranial and neral),β-pinene,geraniol,cis-verbenol and citronellol.In addition,there were a variety of aldehydes,alcohols,lipids,terpenes and ketones and other compounds in the Cymbopogon citratus(DC.)Stapf oil.Test results shown that the sample component was detected with the lowest components in November with only 17 kinds of ingredients separated.In July,we detected the highest isolated sample components,and identified 32 compounds,in May,June,August,September and October with 23 kinds,22 kinds,30 kinds,26 kinds and 23 kinds of components respectively.Quantitative analysis of the main component of Cymbopogon citratus(DC.)Stapf oil,citral(geranial and neral)enjoyed the highest essential oil ingredients among the seven samples,of which the highest value reached 279.286 mg·mL-1 in August and the lowest value appeared in October of 115.366 mg·mL-1;Followed byβ-pinene,which the highest value appeared in August to 40.129 mg·mL-1 and the lowest value appeared in June to 22.861 mg·mL-1;The next was geraniol,its content highest value in August was 40.675 mg·mL-1 while lowest in November to 4.284 mg·mL-1.The containing of P-caryophyllene was rather low,which had shown small amount of detecting results at the beginning of May to July in the sampling.Its highest value was 2.955 mg·mL-1 in August and was found not exist in the samples in November.(3)The research on the biological activity for Cymbopogon citratus(DC.)Stapf oil shown obvious antimicrobial activity against Staphylococcus aureus,Bacillus subtilis,Escherichia coli,Penicillium citrinum,Yeast,Mucor sufu;Wherein,the minimum inhibitory concentration(MIC)were 0.005,0.005,0.01,0.02,0.02,0.02 mL/mL for Staphylococcus aureus,Bacillus subtilis,Escherichia coli,Penicillium,Yeasts and Mucor sufu.Minimum bactericidal concentrations(MBC)were 0.01,0.01,0.02,0.1,0.1,0.1 mL/mL.In the complex inhibitory activity of Cymbopogon citratus(DC.)Stapf essential oil,the Cymbopogon citratus(DC.)Stapf oil mixed with Cunninghamia Lanceolata(Lamb)Hook oil and Cupressus funebris Endl oil in the rate of 1:1.The result had shown that the antibacterial effect of the composite oil was not good as that of Cymbopogon citratus(DC.)Stapf oil.Inhibitory effect of Cymbopogon citratus(DC.)Stapf oil and Cunninghamia Lanceolata(Lamb)Hook oil on Mucor sufu was similar to that of Cymbopogon citratus(DC.)Stapf oil,but other bacteria had been weakened.Inhibitory effect of Cymbopogon citratus(DC.)Stapf oil and Cunninghamia Lanceolata(Lamb)Hook oil was better than that of Cymbopogon citratus(DC.)Stapf oil mixed with Cupressus funebris Endl oil. |
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