超声强化超临界CO2萃取人参皂苷的研究

为了探讨超声波对超临界CO₂萃取(SCE)的影响，考察了在不同萃取温度、萃取压力、萃取时间和流体流量下，有、无超声时超临界CO₂萃取人参皂苷的萃取率。试验结果发现，超声强化超临界CO₂萃取(USCE)的合适萃取温度比没加超声(SCE)时的低10℃；在各自合适的萃取压力下，USCE的皂苷萃取率是SCE的1.64倍；CO₂流体的流量大更有利于USCE。在SCE中，超声的加入能明显提高产物的萃取率和生产效率，降低生产能耗和节     

超临界CO2萃取万寿菊花中叶黄素的研究

采用超临界CO₂萃取技术,研究了从万寿菊花中萃取叶黄素的工艺条件。对影响超临界CO₂萃取叶黄素的各种因素,包括分离参数、原料含水率、粉碎粒径，超临界萃取温度、压力、流速、时间等因素进行了考察,得到较佳的萃取工艺条件为:原料含水率10.92％，粒径40目，萃取温度60℃，压力30 MPa，CO₂流速15 L/h，分离釜Ⅰ温度40℃，压力6 MPa，分离釜Ⅱ温度20℃，时间为6 h。     

超临界CO2萃取大蒜精油及油树脂的研究

研究了大蒜精油及油树脂的超临界CO₂提取工艺，探讨了粒度，萃取及分离的温度、压力和时间对各萃取率的影响，建立了萃取温度、压力与各萃取率的数学模型。确定了超临界CO₂同时提取大蒜精油及油树脂的优化工艺条件。     

超临界CO2提取分离银杏叶药用成分的工艺研究

该文从理论与实践两方面着手，研究探讨超临界CO₂提取分离银杏叶药用成分的适用性和可操作性，提出溶剂浸提与超临界流体萃取相结合的生产工艺，既可降低生产成本，保证产品质量，又可大幅度削减设备造价，为超临界流体萃取技术的实际应用创造条件。     

超临界CO2流体萃取杏仁油工艺研究

该研究以单因素试验和正交试验相结合的方法对苦杏仁脂肪油的超临界CO₂萃取工艺进行了研究。确定了超临界CO₂萃取杏仁油的最佳工艺为：萃取压力35 MPa、萃取温度50℃、CO₂流量24 L/ｈ、粒径60目、萃取时间2 h。各因素影响杏仁的得率的顺序为：粒径>时间>萃取压力>CO₂流量>萃取温度。最佳工艺验证试验的杏仁油的得率为52.98％。本研究的结果为下一步综合、无毒、高效地开发利用苦杏仁奠定了基础。     

用超临界CO2脱除绿茶浓缩液中咖啡碱的工艺研究

对绿茶浓缩液中咖啡碱的超临界CO₂萃取工艺进行了研究，通过4因素正交试验探讨了浓缩液的浓度、操作压强、操作温度、萃取时间对咖啡碱脱除率的影响。结果表明，超临界CO₂萃取技术可以有效地脱除绿茶浓缩液中大部分的咖啡碱，在此基础上完成了用超临界CO₂脱除绿茶浓缩液中咖啡碱的连续作业试验，从而获得了加工脱咖啡碱绿茶浓缩液或速溶绿茶的新工艺。     

基于超临界CO2萃取技术的廿八碳醇富集研究

对于小麦胚芽油超临界CO₂提取过程中廿八碳醇的浓缩问题进行了研究。分析了小麦胚芽油中廿八碳醇的溶解度特性,提出了通过直接的超临界CO₂萃取和使用两级分离的途径提高所得小麦胚芽油中廿八碳醇的方法,以上试验均取得了一定效果。     

超临界CO2流体萃取技术提取核桃油的研究

以新鲜的核桃仁为原料，研究了在超临界状态下物料的粉碎度、萃取压力、萃取温度、萃取时间对核桃油萃取效果的影响。结果表明，超临界CO₂流体萃取核桃油的最佳工艺条件为粉碎度30目、萃取压强30 MPa、萃取温度45℃、萃取时间5 h，此条件下核桃油的萃取率可达93.98%。     

裸大麦中生育三烯酚的超临界CO2流体萃取工艺

采用四元二次通用旋转设计研究了裸大麦中生育三烯酚的超临界CO₂流体萃取工艺。结果表明：萃取温度对生育三烯酚提取率有显著影响，乙醇添加量和萃取时间对生育三烯酚提取率有极显著影响，而萃取压力对生育三烯酚提取率无显著影响，但萃取压力和乙醇添加量的交互项对生育三烯酚提取率有显著影响；在本实验条件下，生育三烯酚最佳超临界CO₂萃取条件为：萃取温度51.8 ℃、萃取压力34.7 MPa、乙醇添加量9%、萃取时间 120 min。     

压力、温度对穿心莲内酯超临界CO2萃取-结晶的影响

以穿心莲浸膏为原料，进行了穿心莲内酯的超临界CO₂萃取结晶分离纯化。考察了单因素参数压力、温度对穿心莲内酯纯度、结晶量等的影响。结果表明：超临界CO₂萃取结晶穿心莲内酯的纯度在结晶板上呈梯度分布；在25 MPa以下，压力升高，结晶板上部晶体纯度升高，而结晶量先增后减；在结晶板下部穿心莲内酯的纯度和结晶量都是先升高后降低；温度在一定范围内能提高晶体纯度，且有利于缩短萃取结晶时间。     

超临界CO2流体技术精制栀子黄色素的研究

以市售栀子黄色素为原料,比较系统地探讨了超临界状态下萃取压力、温度、时间、ＣＯ₂流量、夹带剂对栀子黄色素ＯＤ值比率的影响。结果表明：高温、高压、添加夹带剂的条件下有利于降低栀子黄色素的ＯＤ值比率,达到精制的目的。     

不同提取方法对甘肃紫斑牡丹籽油品质的影响

为了对比冷榨法、溶剂浸出法、超临界CO₂萃取法3种提取方法所得紫斑牡丹籽油的品质,以甘肃紫斑牡丹籽为研究对象,从外观品质、出油率、理化特性及抗氧化能力方对3种方法提取的牡丹籽油品质进行观测。结果表明,采用溶剂浸提法提取的牡丹籽油得率最高,为27.27%;其次是超临界CO₂萃取法,为22.80%;冷榨法最低,为20.17%。采用超临界CO₂萃取法提取的牡丹籽油酸值和过氧化值低,抗氧化性能强,油品质量最高。采用冷榨法提取的牡丹籽油酸值低,品质较好,方法操作简单。3种提取方法各有特点,生产中可根据具体需求选择适用。     

不同参数超临界CO2处理对乳酸菌活性的影响

为了研究超临界CO₂作为非水相介质在生化反应工程中的作用，有必要考察超临界CO₂处理对微生物活性的影响。本文以乳酸杆菌为试验菌种，进行了该菌在不同参数超临界CO₂处理对菌体生长曲线、耐渗透压能力、耐酸能力、抑菌能力、降解胆固醇能力等活性指标影响的研究。结果表明：当提高超临界CO₂压强或延长超临界CO₂处理时间，乳酸杆菌的活性指标会发生如下变化：生长曲线的最大菌体浓度降低，但菌体的生长速率差异不大；菌体的耐渗透能力、耐酸能力降低；所得的抑菌圈比较明显，但抑菌圈直径减小；平均胆固醇降解率降低，而且长时间处理对降解效果的影响比高压强处理的明显。因此，在工程应用中需要研究一定的弥补措施。     

CO2 emissions from subtropical arable soils of China

CO₂ efflux plays a key role in carbon exchange between the biosphere and atmosphere, but our understanding of the mechanism controlling its temporal and spatial variations is limited. The purpose of this study is to determine annual soil CO₂ flux and assess its variations in arable subtropical soils of China in relation to soil temperature, moisture, rainfall, microbial biomass carbon (MBC) and dissolved organic carbon (DOC) using the closed chamber method. Soils were derived from three parent materials including granite (G), tertiary red sandstone (T) and quaternary red clay (Q). The experiment was conducted at the Ecological Station of Red Soil, The Chinese Academy of Sciences, in a subtropical region of China. The results showed that soil CO₂ flux had clear seasonal fluctuations with the maximum value in summer, the minimum in winter and intermediate in spring and autumn. Further, significant differences in soil CO₂ flux were found among the three red soils, generally in the order of G>T>Q. The average annual fluxes were estimated as 2.84, 2.13 and 1.41 kg CO₂ m⁻² year⁻¹ for red soils derived from G, T and Q, respectively. Soil temperature strongly affects the seasonal variability of soil CO₂ flux (85.0-88.5% of the variability), followed by DOC (55.8-84.4%) and rainfall (43.0-55.8%). The differences in soil CO₂ flux among the three red soils were partly explained by MBC (33.7-58.9% of the variability) and DOC (23.8-33.6%).     

Sources of CO2 efflux from soil and review of partitioning methods

Five main biogenic sources of CO₂ efflux from soils have been distinguished and described according to their turnover rates and the mean residence time of carbon. They are root respiration, rhizomicrobial respiration, decomposition of plant residues, the priming effect induced by root exudation or by addition of plant residues, and basal respiration by microbial decomposition of soil organic matter (SOM). These sources can be grouped in several combinations to summarize CO₂ efflux from the soil including: root-derived CO₂, plant-derived CO₂, SOM-derived CO₂, rhizosphere respiration, heterotrophic microbial respiration (respiration by heterotrophs), and respiration by autotrophs. These distinctions are important because without separation of SOM-derived CO₂ from plant-derived CO₂, measurements of total soil respiration have very limited value for evaluation of the soil as a source or sink of atmospheric CO₂ and for interpreting the sources of CO₂ and the fate of carbon within soils and ecosystems. Additionally, the processes linked to the five sources of CO₂ efflux from soil have various responses to environmental variables and consequently to global warming. This review describes the basic principles and assumptions of the following methods which allow SOM-derived and root-derived CO₂ efflux to be separated under laboratory and field conditions: root exclusion techniques, shading and clipping, tree girdling, regression, component integration, excised roots and insitu root respiration; continuous and pulse labeling, ¹³C natural abundance and FACE, and radiocarbon dating and bomb-¹⁴C. A short sections cover the separation of the respiration of autotrophs and that of heterotrophs, i.e. the separation of actual root respiration from microbial respiration, as well as methods allowing the amount of CO₂ evolved by decomposition of plant residues and by priming effects to be estimated. All these methods have been evaluated according to their inherent disturbance of the ecosystem and C fluxes, and their versatility under various conditions. The shortfalls of existing approaches and the need for further development and standardization of methods are highlighted.     

Soil CO2 efflux vs. soil respiration: Implications for flux models

In the long term, all CO₂ produced in the soil must be emitted by the surface and soil CO₂ efflux (FCO₂) must correspond to soil respiration (R_soil). In the short term, however, the efflux can deviate from the instantaneous soil respiration, if the amount of CO₂ stored in the soil pore-space (SCO₂) is changing. We measured FCO₂ continuously for one year using an automated chamber system. Simultaneously, vertical soil profiles of CO₂ concentration, moisture, and temperature were measured in order to assess the changes in the amount of CO₂ stored in the soil. R_soil was calculated as the sum of the rate of change of the CO₂ storage over time and FCO₂. The experiment was split into a warm and a cold season. The dependency of soil respiration and soil efflux on soil temperature and on soil moisture was analyzed separately. Only the moisture-driven model of the warm season was significantly different for FCO₂ and R_soil. At our site, a moisture-driven soil-respiration model derived from CO₂ efflux data would underestimate the importance of soil moisture. This effect can be attributed to a temporary storage of CO₂ in the soil pore-space after rainfalls where up to 40% of the respired CO₂ were stored.