Study On Antioxidant Activities And Microencapsulation Of Lemon Grass Essential Oil

Lemon grass, a Gramineae Cymbopogon herb, has a cultivation history of more than thousands of years all over the country. It mainly grow in the tropical and subtropical regions, and in China, it is mainly cultivated in guangdong, fujian, guangxi, yunnan province. Related studies have shown that lemon grass essential oil not only can be used as seasoning spices, medicine, cosmetics and other fields used for flavoring, but also has good anti-oxidation, anti-tumor, antibacterial and insecticidal and other biological activity. In this paper, lemon grass oil extraction method, antioxidant activity of essential oils and molecular microencapsulation were studied.The researches about volatile oils of lemon grass in this thesis included three aspects:(1) Essential oil was extracted from the leaves by hydrodistillation (HD) and Microwave-assisted hydrodistillation (MAE), and optimal extraction conditions were achieved as follows: by HD, the ratio of bark powder to water 1:15 (w/v), distilling 2 hours by vapour,and the extraction rate of three lemon grass is up to 2.61 %, 2.5 %, 1.26%, respectively; by MAE, the best condition of Cymbopogon citratus is power 800W, radiant time 5 minute; the best condition of C.winterianus is power 600W, radiant time 6 minute; the best condition of C.nardus is power 800W, radiant time 4 minute; and the ratio of bark powder to water 1:15 (w/v),distilling 90 min by 200W, and the extraction rate is up to 2.77 %, 2.67 %, 1.37 %, respectively. Essential oils extracted by two methods were analyzed by GC-MS. The main component of C.citratus is citral, and so is citronellal in C. winterianus, and nerol in C. nardus.(2) The anti-oxidative activities of lemon grass were evaluated based on hydroxyl radical, superoxide anion scavenging activities and phosphomolybdenum complex. The results revealed that lemon grass has notable anti-oxidative activity.(3) The inclusion of volatile oil of lemon grass withβ-cyclodextrins was prepared by saturated aqueous solution and the optimal conditions were ascertained: the interaction temperature is 20°C, the interaction time is 20 minute. The inclusion interactions of oils withβ-CD were determined by infrared spectrometry and microscope. The stability of essential oil in the microcapsules was obviously improved.