| The pomelo peel essential oil has the unique graceful fragrance, it will cause the human to produce one kind freshly and pleasant sensation. It was unable to chemical synthesis by using chemistry method until now and also can′t use other citrus fruits essence to replace. The domestic and foreign market's demand increases at a rate of 18% every year. It has been widely used in food and cosmetics industry, such as drink, jam, cakes and so on. The thesis emphasis on the steam distillation combined with the simultaneous distillation techniques to extract essential oil from the peel of Citrus grandis (L.) Osbeck. cv . guanxi miyou, high quality products were acquired, the composition of essential oil were analyzed by gas chromatography–mass spectrum. The various factors that had effects on the microencapsulation of essential oil including selection of wall materials, formulation of compound wall materials, proportion of core-material and wall-material, inlet concentration of emulsion, homogenizing pressure, and temperature of entering wind and out wind were systematically studied by means of spray drying technique. The formulation of the microencapsulated products and the technology conditions were optimized by quadratic general rotary unitized design experiments. The outer structures of the microcapsules were observed by Scanning Electron Microscopy (SEM). The result showed that: 1 Through the single factor experiment determined the effects on the extraction rate of pomelo peel oil, such as the soaking time, distillation time, stock-water ratio and the degree of fragmentation and so on. The optimum extraction technological conditions according to orthogonal tests are as follows. Dry peel: Distillation-soaking for 9h, distilling for 6h, solution ratio of 12 ml/g, seed fragmentation degree of 20 mesh. Frozen peel: Distillation-soaking for 3h, distilling for 5h, solution ratio of 5ml/g. Under the optimum conditions, the essential oil rate is respectively 0.55% and 1.96%.2 Through the single factor experiment determined the effects on the extraction rate of pomelo peel oil, such as the soaking time, distillation time, stock-water ratio and the degree of fragmentation and so on. The optimum extraction technological conditions according to orthogonal tests are as follows. Dry peel: Distillation-soaking for 12h, distilling for 4h, solution ratio of 15 ml/g, seed fragmentation degree of 20 mesh. Frozen peel: Distillation-soaking for 4h, distilling for 5h, solution ratio of 4ml/g. Under the optimum conditions, the essential oil rate is respectively 1.14% and 2.32%.3 The physics and chemistry index of essential oil were detected: the oil was yellow clarification liquid, has the fresh pomelo peel characteristic fragrance, relative density:0.8530-0.8560, refractive index:1.4720-1.4740;acid value<2;ester value10-11; 1 volume essential oil dissolves in 5-6 time of ethyl alcohol. The components of oil from distillation and simultaneous distillation had no large difference, both of them have high quality.4 The composition of essential oil were analyzed by GC-MS, the results showed that: the dominating compositions were d-Limonene,β-Myrcene, Nootkatone, Germacrene, Geraniol etc. In the oil of fresh peel, the highest content is d-limonene,52.37%, secondly isβ-Myrcene,26.07%. The distillation oil has more components than SDE oil, but the content of Nootkatone in SDE oil is more than a time in distillation oil.5 Using simplex centroid design determined the optimum formulation of products: Arabic gum22.7%, Dextrin35.2%, High fructose cornsyru42.1%. Through orthogonal experiment and quadratic general rotary unitized design, the optimum technological were determined also. Monoglycerides and sucrose esters weight ratio is 1:9, emulsifier content 0.8%, proportion of core-material and wall-material is 1:2, inlet concentration of emulsion20%, homogenizing pressure 30Mpa, temperature of entering wind183℃, feed rate 16 mL·min-1, stream pressure0.09 MPa, Under the optimum conditions, the encapsulation rate of product is 86.1%.6 The final products had a good appearance, properties and characteristics. They have acceptable taste and smell,dry, spherical and good fluidity. The content of water was 2.87%, density 0.43g/cm3, solubility 90.5%. The granularity was 15um, has hollow slightly in the pellet surface.
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