“萃取”是一個被廣泛應用的實驗手法，它讓我們能對植物或其他生物體裡的化合物進行化學分析。然而，我們對於萃取的動力學研究相對缺乏。在2014年，由李三保、徐邦達和洪淑媚共同提出的 ” Modelling of isothermal chlorophyll extraction from herbaceous plants” 建立了一個描述葉綠素萃取的數學模型，而此模型能成功的描述草本植物的葉綠素萃取。在此研究，我們想擴大檢驗此模型的可用性，挑選生物結構更複雜的茶樹種(Camellia sinensis)來進行萃取，選擇茶菁與經過製茶過程的乾茶葉兩種型態的樣品，除了用有機溶劑萃取葉綠素外，我們也使用去離子水來萃取咖啡因，來觀察有機溶劑和去離子水萃取的差異。另外，我們也進行潛變測試來了解樣品的機械性質，以及量測接觸角來了解表面能的差異。而研究成果表示此模型也能在上述提到的各種不同樣品條件下使用，並和實驗數據都有高度的吻合性。藉由此模型，我們能得知樣品萃取的擴散係數、潤溼時間和鬆弛時間等和動力學相關的參數。而這個萃取模型也有潛力應用在茶葉的去咖啡因加工和高經濟價值的兒茶素萃取上。

Extraction is an experimental method wildly used in chemical analysis, but there are relatively few kinetic researches. In 2014, S. Lee, B.D. Hsu and S.M. Hung published” modelling of isothermal chloro-phyll extraction from herbaceous plants”. This model established a mathematical model to describe the kinetics of chlorophyll extraction, and had a success on herbaceous plants. In this study, we try to use this model on Camellia sinensis, which is a more complex plant, and both fresh leaves and dried leaves had been tested. We also extract caffeine, which is extracted by DI water in this study, to distinguish DI water from organic solvents. Furthermore, creep test had been accomplished to study the mechanic properties of fresh leaf, and contact angle had been executed to study surface energies of fresh and dried leaf. Finally, this model have good prediction on each condition mentioned above, and we got the diffusion coefficient, wetting time and relaxation time from extraction model. We discover that chlorophyll extraction in fresh leaves is much easier than dried leaves, but caffeine extraction is not. Rate of chlorophyll extraction depends on the polarity of solvents. The model has the potential on decaffeination and catechins extraction of tea leaf in the future.

1. D.A. Balentine, S.A. Wiseman and L.C. Bouwens, The chemistry of tea flavonoids. Critical Reviews in Food Science and Nutrition, 37, 693~704 (1997).
2. Y. Hara, S.J. Luo and R.L. Wickremashinghe V. Chemical composition of tea. Food Reviews International, 11, 435-456 (1995).
3. S.P.J.N. Senanayake , Green tea extract: Chemistry, antioxidant properties and food applications – A review. Journal of Functional Foods, 5(4), 1529~1541 (2013).
4. C. Dufresne and E. Farnworth, Tea, Kombucha, and health: a review. Food Research International, 33(6), 409~421 (2000).
5. Y. Hernández, M.G. Lobo, and M. González, Factors affecting sample extraction in the liquid chromatographic determination of organic acids in papaya and pineapple. Food Chemistry,. 114, 734~741 (2009).
6. X.Pan, G. Niu and H. Liu, Microwave-assisted extraction of tea polyphenols and tea caffeine from green tea leaves. Chemical Engineering and Processing: Process Intensification, 42(2), 129~133 (2003).
7. P.P. Rahayu, Purwadi and L.E. Radiati, Physico Chemical Properties of Whey Protein and Gelatine Biopolymer Using Tea Leaf Extract as Crosslink Materials. Current Research in Nutrition and Food Science, 3, 224~236 (2015).
8. C.J. Chang, K.L. Chiu and Y.L. Chen, Separation of catechins from green tea using carbon dioxide extraction. Food Chemistry, 68(1), 109~113 (2000).
9. T. Xia, S. Shi, and X. Wan, Impact of ultrasonic-assisted extraction on the chemical and sensory quality of tea infusion. J. Food Eng., 74, 557~560 (2006).
10. H.S. Park, H.J. Lee, M.H. Shin and K.W. Lee , Effects of cosolvents on the decaffeination of green tea by supercritical carbon dioxide. Food Chemistry, 105(3), 1011~1017 (2007).
11. X. Jun and S. Deji, Characterization of polyphenols from green tea leaves using a high hydrostatic pressure extraction. International Journal of Pharmaceutics, 382, 139~143 (2009).
12. M. Peleg, An Empirical Model for the Description of Moisture Sorption Curves. Food science, 53(4), 1216~1217 (1988).
13. R. Horanni and U. H. Engelhardt, Determination of amino acids in white, green, black, oolong, pu-erh teas and tea products. Journal of Food Composition and Analysis, 31(1), 94~100 (2013).
14. S. Jokić, D. Velić, M. Bilić and B. Kojić, Modelling of the Process of Solid-Liquid Extraction of Total Polyphenols from Soybeans. Food Science, 28, 206~212 (2010).
15. C. Lin, G. Xia, and S. Liu, Modeling and comparison of extraction kinetics of 8 catechins, gallic acid and caffeine from representative white teas. Food Science and Technology, 83, 1~9 (2017).
16. S.P.S. Herodez, M. Hadolin and M. Škerget Solvent extraction study of antioxidants from Balm (Melissa officinalis L.) leaves. Food Chemistry, 80, 275~282 (2003).
17. C.H. Chan, R. Yusoff, and G.C. Ngoh, Modeling and kinetics study of conventional and assisted batch solvent extraction. Chemical Engineering Research and Design, 92(6), 1169~1186 (2014.)
18. S.M. Hung, B.D. Hsu, and S. Lee, Modelling of isothermal chlorophyll extraction from herbaceous plants. Journal of Food Engineering, 128, 17~23 (2014).
19. Z. Šesták, J. Catsky and P.G. Jarvis, Determination of chlorophylls a and b, Plant Photosynthetic Production: Manual of Methods, W.N.V. Junk edit., Springer, The Hague, Netherlands, 672~701 (1971).
20. H.K. Lichtenthaler, Chlorophylls and carotenoids: Pigments of photosynthetic biomembranes. Methods Enzymol, 148, 350~382 (1987).
21. R.J. Porra , W.A. Thompson, and P.E. Kriedemann, Determination of accurate extinction coefficients and simultaneous equations for assaying chlorophylls a and b extracted with four different solvents:verification of the concentration of chlorophyll standards by atomic absorption spectroscopy. Biochimica et Biophysica Acta, 975, 384~394 (1989).
22. N. Sumanta, , Choudhury Imranul Haque and Jaishee Nishika, Spectrophotometric Analysis of Chlorophylls and Carotenoids from Commonly Grown Fern Species by Using Various Extracting Solvents Research Journal of Chemical Sciences, 4, 63~69 (2014).
23. M. Edelenbos, L.P. Christensen, and K. Grevsen, HPLC Determination of Chlorophyll and Carotenoid Pigments in Processed Green Pea Cultivars (Pisum sativum L.). Food Chemistry, 49, 4768~4774 (2001).
24. M. Sanja, Milenković and Jelena B. Zvezdanović, The identification of chlorophyll and its derivatives in the pigment mixtures: HPLC-chromatography, visible and mass spectroscopy studies. Advanced technologies, 1, 16~24 (2012).
25. H. Küpper, M. Spiller, and F.C. Küpper, Photometric Method for the Quantification of Chlorophylls and Their Derivatives in Complex Mixtures:Fitting with Gauss-Peak Spectra. Analytical Biochemistry, 286, 247~256 (2000).
26. Q.V. Vuong, B. John and M.H. Nguyen , Preparation of decaffeinated and high caffeine powders from green tea. Powder Technology, 233, 169~175 (2013).
27. H. Liang, Yuerong Liang and Junjie Dong, Decaffeination of fresh green tea leaf (Camellia sinensis) by hot water treatment. Food Chemistry, 101, 1451~1456 (2007).
28. T. Shiono, Selective decaffeination of tea extracts by montmorillonite. Journal of Food Engineering, 200, 13~21 (2017).
29. D.F. Swinehart, The Beer-Lambert Law. ACS Publications, 39, 333~335 (1962).
30. M. Pflanz and M. Zude, Spectrophotometric analyses of chlorophyll and single carotenoids during fruit development of tomato (Solanum lycopersicum L.) by means of iterative multiple linear regression analysis. APPLIED OPTICS, 47, 5961~5970 (2008).
31. C.K. Liu, S. Lee, W.J. Cheng, C.J. Wu and I F. Lee, Water absorption in dried beans. Journal of the Science of Food and Agriculture, 85, 1001~1008 (2005).
32. Y.W. Huang, Mechanical properties of nylon 6 artificial muscle. Master Thesis, National Tsing Hua university, 48~50 (2016).
33. L.F. Wang, Y. Lee and J.O. Chung, Discrimination of teas with different degrees of fermentation by SPME–GC analysis of the characteristic volatile flavour compounds. Food Chemistry, 109, 196~206 (2008).
34. D.K. Owens and R.C. Wendt, Estimation of the surface free energy of polymers. Journal of Applied Polymer Science, 13, 1741~1747 (1969).
35. F.M. Fowkes, Attractive forces at interfaces. Industrial and Engineering Chemistry, 56, 40~52 (1964).
36. M. Żenkiewicz, , Methods for the calculation of surface free energy of solids. Journal of achievements in materials and manufacturing engineering, 24(1), 137~145 (2007).
37. L. Schreiber and M. Riederer, Ecophysiology of cuticular transpiration: comparative investigation of cuticular water permeability of plant species from different habitats. Ecophysiology, 107, 426~432 (1996).
38. G. Kerstiens, Cuticular water permeability and its physiological significance. Journal of Experimental Botany, 47, 1813~1832 (1996).
39. M. Riederer, Thermodynamics of the water permeability of plant cuticles: characterization of the polar pathway. Journal of Experimental Botany, 57, 2937~2942 (2006).
40. X. Jun, Caffeine extraction from green tea leaves assisted by high pressure processing. Journal of Food Engineering, 94, 105~109 (2009).
41. I.M. Smallwood, Handbook of organic solvent properties. Amold and Halsted Press an imprint of John Wdey & Sons Inc. (1996).
42. H.K. Lichtenthaler and C. Buschmann, Chlorophylls and Carotenoids: Measurement and Characterization by UV-VIS Spectroscopy. Current Protocols in Food Analytical Chemistry, , F4.3.1~F4.3.8 (2001).
43. C.Y. Lin, Mass transfer of coffee bean. Master Thesis, National Tsing Hua university, 64~65 (2016).
44. L.L. Shipman, T. M. Cotton and J. R. Norris, An analysis of the visible absorption spectrum of Chlorophyll a monomer, dimer, and oligomers in solution. Journal of the American Chemical Society, 344~346 (1976).