绿茶中咖啡因在超临界二氧化碳中的溶解度：理论与实证方法
Solubility of caffeine from green tea in supercritical CO2: a theoretical and empirical approach.
作者信息
Gadkari Pravin Vasantrao, Balaraman Manohar
机构信息
Department of Food Engineering, CSIR (Council of Scientific and Industrial Research, India) - Central Food Technological Research Institute, Mysore, 570 020 India ; Academy of Scientific and Innovative Research, CSIR-CFTRI, Mysore, India.
出版信息
J Food Sci Technol. 2015 Dec;52(12):8004-13. doi: 10.1007/s13197-015-1946-5. Epub 2015 Aug 1.
Decaffeination of fresh green tea was carried out with supercritical CO2 in the presence of ethanol as co-solvent. The solubility of caffeine in supercritical CO2 varied from 44.19 × 10(-6) to 149.55 × 10(-6) (mole fraction) over a pressure and temperature range of 15 to 35 MPa and 313 to 333 K, respectively. The maximum solubility of caffeine was obtained at 25 MPa and 323 K. Experimental solubility data were correlated with the theoretical equation of state models Peng-Robinson (PR), Soave Redlich-Kwong (SRK), and Redlich-Kwong (RK). The RK model had regressed experimental data with 15.52 % average absolute relative deviation (AARD). In contrast, Gordillo empirical model regressed the best to experimental data with only 0.96 % AARD. Under supercritical conditions, solubility of caffeine in tea matrix was lower than the solubility of pure caffeine. Further, solubility of caffeine in supercritical CO2 was compared with solubility of pure caffeine in conventional solvents and a maximum solubility 90 × 10(-3) mol fraction was obtained with chloroform.
在乙醇作为共溶剂的存在下，采用超临界CO₂对新鲜绿茶进行脱咖啡因处理。在压力范围为15至35MPa、温度范围为313至333K时，咖啡因在超临界CO₂中的溶解度分别从44.19×10⁻⁶变化到149.55×10⁻⁶（摩尔分数）。咖啡因的最大溶解度在25MPa和323K时获得。实验溶解度数据与状态方程理论模型彭-罗宾逊（PR）、索阿韦-雷德利希-邝（SRK）和雷德利希-邝（RK）进行了关联。RK模型对实验数据的回归平均绝对相对偏差（AARD）为15.52%。相比之下，戈尔迪略经验模型对实验数据的回归效果最佳，AARD仅为0.96%。在超临界条件下，咖啡因在茶叶基质中的溶解度低于纯咖啡因的溶解度。此外，将咖啡因在超临界CO₂中的溶解度与纯咖啡因在传统溶剂中的溶解度进行了比较，用氯仿获得的最大溶解度为90×10⁻³摩尔分数。
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