| Supercritical fluid extraction is a newly developed technology, which shows excellent properties in extraction of functional components of medicinal plants and spices. It is widely used in food and medicine industries. Supercritical CO2 (FC-CO2) extraction was used in decaffeination of green tea and extraction of tea catechins, tea seed oil and volatile compounds of tea, Chrysanthemum indicum flower and Chrysanthemum Morifolium flower in the present paper.Cosolvent, particle size of tea, extraction temperature and extraction time had significant effect on decaffeination of green tea. When water and aqueous ethanol solution were used as cosolvents during decaffeination of green tea, a high percentage of catechins was removed. It suggests that water and aqueous ethanol were not suitable cosolvents used in decaffeination of green tea. When pure ethanol was used as cosolvent, caffeine was specifically extracted from green tea. Orthogonal array design tests showed that the effects of the above four factors followed the sequence of particle size> extraction temperature> ethanol cosolvent volume> extraction time. The optimal protocol for green tea decaffeination was screened as 10 g of 0.2-0.6 mm particle size green tea being extracted using 15 ml ethanol cosolvent at 80℃for 120 min at SC-CO2 flow rate 1.5 L/min and pressure 30MPa. In this case,70.2%caffeine was removed, with 93.8%catechins being remained in the decaffeinated green tea.When the decaffeinated green tea was used as material to prepare catechins, water could be used as cosolvent. The influences of extracting pressure, extracting temperature, extracting time, particle size of tea and cosolvent volume on extraction of catechins was investigated. The optimal extraction conditions were as follows:10 g 0.2-0.6 mm particle size tea being extracted using 40 mL water cosolvent, for 3 h at 80℃and 40 MPa. However, this method had no significant advantage over method of hot water extraction. It is recommended that green tea was decaffeinated by SC-CO2 extraction and then extracted in hot water so as to prepare decaffeinated catechins.Orthogonal array design with factors of extraction temperature, extraction pressure and extraction time showed that optimum conditions for SC-CO2 extraction of volatiles from green tea were as follows:extraction temperature 50℃, extraction time 90min, pressure 20 MPa. In this case, the yield of flavor components was 28.5 g per one kg green tea. The composition of the volatiles were compared with those extracted by simultaneous distillation extraction (SDE) and solid phase micro extraction (SPME). Gas chromatography and mass spectrometry (GC-MS) showed that 41 compounds were identified in volatiles extracted by SC-CO2, with abundant components n-hexadecanoic acid, octadecanoic acid, phytol and tetradecanoic acid.49 compounds were identified in volatiles extracted by SDE, similar as that of SC-CO2.39 components were identified in volatiles extracted by SPME, in which the abundant components were 3,7-dimethyl-1,6-octadien-3-ol,3-buten-2-one,4-(2,6,6-trimethyl-l-cyclohexen-1-yl)-alph a-farnesene, and 3,7-dimethyl-1,5,7-octatrien-3-ol.28 compounds were simultaneously detected in the three volatile extracts.SC-CO2 extraction was used in extraction of oil from tea seeds of different tea cultivars. The optimal conditions for SC-CO2 extraction of tea seed oil were that dry tea seed with particle size 0.25-0.38mm was extracted at 40 MPa and 45℃for 120 min. The oil yield was up to 293.4 g/kg. The quality indicators of tea seed oil extracted by SC-CO2, such as oil color, turbidity, iodine value, acid value and peroxide index, were better than those extracted by other. It is considered that SC-CO2 extraction is a promising method to extract tea seed oil.Volatiles and flavonoids in Chrysanthemum Morifolium Ramat flower and Chrysanthemum indicum flower were determined by respectively. The major volatile compounds were 2,6,6-trimethyl-bicyclo[3.1.1]hept-2-en-4-ol, 2-(2,4-hexadiynylidene)-1,6-dioxaspiro[4.4]non-3-ene, germacrene D, a-neoclovene, eucalyptol in Chrysanthemum indicum flower.β-Humulene was the most abundant volatile and ledene oxide-(I) the next abundant in Chrysanthemum Morifolium Ramat flower.The flavonoid compositions of Chrysanthemum indicum flower and Chrysanthemum Morifolium Ramat flower were compared in this study. Luteolin-7-glucoside and quercitrin were the most abundant flavonoids in Chrysanthemum Morifolium Ramat flower, but quercitrin, myricetin and luteolin-7-glucoside were abundant flavonoids in Chrysanthemum indicum flower. It is considered that the difference in physiological functions of the two flowers might be related to their difference in flavonoid compositions. |
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