| Citrus peels essential oils has fresh and pleasant aroma. Because it is a low boiling point volatile substances, some of the components will volatilize at room temperature or below room temperature conditions with poor stability,short fragrant time. The highest essential oil content of olefins terpene oils substance not only has small contribution but also it is easy to oxide and deteriorate, leading to decline in the quality and aroma of essential oils,as a result,affecting the quality and use of essential oils.In order to improve the stability of citrus peels essential oil, this paper optimized the technology of separating limonene from citrus peels essential oils by vacuum distillation at first;Then removed terpene from citrus peels essential oil and analyzed the changes of main chemical ingredient content at different storage conditions;Finally studied the effects of different embedded conditions on the citrus peels essential oil microcapsules preparated by (3-cyclodextrin, and optimized the technical condition with single factor experiment and response surface methodology,and analyzed the structure of the microcapsules with scanning electron technology.The main research content methods and results were as follows:(1) Compared the effect of vacuum distillation and steam distillation separation limonene, reduced vacuum distillation separation effect is better.The limonene from citrus peels essential oils were separated by vacuum distillation, and identified the separated product through the refractive index, the specific rotation and the relative density. Then by the Gas chromatography-mass spectrometry technology, The effects of distillation time, temperature on limonene separation were discussed, The results showed that under vacuum0.1MPa,the optimal separating process for limonene was170℃,and l0min. Under this condition the terpene separate rate was about92.38%, the specific rotation of terpene separate Citrus peels essential oils was+32.3°.(2)It focused on terpene separate Citrus peels essential oils and took non terpene separate Citrus peels essential oils as a comparison, using using different manner of packing(transparent,light avoiding),different temperature(l0℃,20℃,30℃),different time(ld,60d,120d,180d)storage terpene separate and non terpene separate Citrus peels essential oils,GC-MS measured the changes of main chemical ingredient content at different storage conditions. The results showed that:both storage at transparent and light avoiding package, at transparent package essential oils have a larger effect on the changes of contents after180d storage,but in light avoiding package essential oils have a little changes, light avoiding was a good way to packing;during storage in brown glass bottle at different temperature, terpene separate Citrus peels essential oils storage at10℃and20℃the content of each component and color values in terpene separate Citrus peels essential oils changed slightly, storage at30℃, the olefins, alcohols, aldehydes,phenols increased, esters,ketones decreased, but non terpene separate Citrus peels essential oils olefins,aldehydes,phenols decreased,others content increased and color deepened. Terpene separate Citrus peels essential oils suitable storaged at10℃～20℃, non terpene separate Citrus peels essential oils are not suitable for storaged at10℃～30℃.(3)The diffrent inclusion conditions on the preparation of non terpene separate citrus peels essential oil microcapsules were investigated.After the single factor experiment, response surface methodology was employed to optimize conditions for affecting the microencapsulation by using citrus peels essential oils as core materials and β-cyclodextrin as wall materials. The effect of wall-to-core material ratio, inclusion temperature,essential ethanol-to-essential oil ratio, inclusion time and β-cyclodextrin-to-water addition ratio on microencapsulation were investigated. The optimal reaction conditions were found to be: inclusion at52℃for2h with wall-to-core material ratio of5.8:1(g/mL), ethanol-to-essential oil ratio of19:1and water addition-to-β-cyclodextrin ratio of8:1(mL/g), resulting in a microcapsules retention rate of65.97%and the embedding rate of90.26%. |
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