David villanueva

9th Green Chemistry Conference. AN INTERNATIONAL EVENT Extraction of caffeine from green coffee beans using ethyl lactate
David Villanueva1, Pilar Luna1, Marina Manic2, Vesna Najdanovic–Visak2 and Tiziana Fornari1 1 Instituto de Investigación en Ciencias de la Alimentación CIAL (CSIC-UAM), Madrid, Spain –[email protected] 2 REQUIMTE, Departamento de Química, Universidade Nova de Lisboa, Caparica, Portugal Keywords: caffeine, ethyl lactate, accelerated solvent extraction.

Coffee decaffeination is an area in which there Different extraction temperatures and particle sizes has been an extraordinary commercialization of were employed, and extraction yield and caffeine supercritical CO2 extraction technology, actuality concentration in the extracts were determined. well recognized as a new emerging clean and Green coffee beans (Coffee Arabica variety) environmental friendly technology, particularly for were ground in a manual mill using liquid nitrogen; particle sizes were classified into two different On the other side, traditionally methods to types: the entire green bean (SP1) and particles in extract caffeine from coffee use water or organic To perform the extractions an ASE 350 system acetate, etc.). Although water is a green solvent, its from Dionex Corporation (Sunnyvale, CA, USA) selectivity is very low and main constitutes of coffee was used, which was equipped with a solvent flavor are considerably co-extracted. Chlorinated controller unit. Figure 1 show a scheme of the solvents are more selectively but are dangerous to experimental device employed. Extractions were handle and the major disadvantage is their toxicity. performed at three different extraction temperatures Among other organic solvents, ethyl acetate is the (100, 150 and 200 ºC) during 10 minutes. most accepted, since this substance is present in several fruits and vegetables. Decaffeination of green coffee beans using ethyl acetate is often called “natural decaffeination”, despite the fact that the solvent employed in the decaffeination process is obtained from synthesis and not from natural sources. Ethyl lactate (ethyl 2-hydroxypropanoate) is a green and economically viable alternative to traditional solvents. It has been recognized as GRAS (general recognized as safe), is fully biodegradable, braking down into carbon dioxide and water, non- Fig. 1 – Scheme of the ASE experimental device. depleting. These attractive characteristics, together with its low volatility, broad liquid temperature The caffeine quantification in the extracts was range, low viscosity and high specific solvent accomplished with a Varian ProStar Analytical abilities, have recently increased the attention to the use of ethyl lactate as a green solvent for several California, USA). The column utilized was Microsorb-MV100 column C-18, 5 µm (250 x 4.6 Moreover, ethyl lactate has been approved by the mm). Based in the method of Sharma et al.8, the U.S. Food and Drug Administration (FDA) as mobile phase, solvent A (acetonitrile) and solvent B pharmaceutical and food additive. Thus, it has also (0.1% ortho-phosphoric acid in water (w/v)), was become the focus of new applications in the food used under binary linear gradient conditions as and pharmacy field. With respect to food follows: t = 0, 10% A; t = 15 min, 30% A; t = 20 applications, main reported potential uses are related min, 35% A; t = 22 min, 20% A; t = 25 min, 10% A. with lipids4, 5 and with the extraction of carotenoids The flow rate was set at 0.8 mL/min and the column temperature was kept at 35 ºC using a column oven. In this work, the potential use of ethyl lactate to Table 1 shows the yields obtained in the remove caffeine from plant matrix is studied for extraction of SP1 (entire) and SP2 (ground) green the first time. Specifically, Accelerated Solvent coffee beans, at the different temperatures studied. Extraction (ASE) was accomplished using ethyl As expected, extraction yield increase with lactate as the high temperature pressurized liquid temperature. Furthermore, as is usual the case, solvent to remove caffeine from green coffee beans. considerable higher extraction yields were obtained As conclusion, it can be established that ethyl when processing the ground beans than when lactate is a potential green solvent to be applied in the decaffeination of green coffee beans and other caffeine plant matrix (green tea leaves, guaraná and cocoa seeds, etc.). Further studies related with the Table 1 – Extraction yield (mass of extract / mass of beans caffeine solubility in liquid ethyl lactate and in x 100) obtained in the ASE of green coffee beans using ethyl lactate. SP1: entire beans; SP2: ground beans. The authors gratefully acknowledge the financial support from the Ministerio de Ciencia e Innovación of Spain (joined project Spain-Portugal, PT2009- 0010). P. Luna acknowledges the postdoctoral Figure 2 show a typical chromatogram obtained contract (JAE), given by the Consejo Superior de at the three studied extraction temperatures (100, Investigaciones Científicas (CSIC), Spain. 1 K. Zosel, Praktische Anwendungen der Stofftrennung Caffeine
mit überkritischen Gasen Angew, Chemie, 1978, 90,
748.
2 H. Peker, M.P. Srinvasan, J.M. Smith, B.J. McCoy, AIChE Journal, 1992, 38, 761.
3 N.L. Rozzi, R.K. Singh, Comprehensive reviews in Tª= 200ºC
Food Science and Food Safety, 2002, 1, 33.
4 E.J. Hernández, P. Luna, R.P. Stateva, V. Najdanovic- Tª= 150ºC
Visak, G. Reglero, T. Fornari, J. Chem. Eng. Data,
2011, 56 (5), 2148.
Tª= 100ºC
5 G. Vicente, A. Paiva, T. Fornari, V. Najdanovic- Visak, Chem. Eng. J. (submitted). 6 B.K. Ishida, M.H. Chapman, J. Agric. Food Chem., Fig. 2 – HPLC chromatogram obtained at 100,150 and 2009, 57, 1051.
200 °C for the ASE of entire coffee beans (SP1) using ethyl 7 I.F. Strati, V. Oreopoulou. Int. J. Food Sci. Tech., 2011, 46, 23.
8 V. Sharma, A. Gulati, S.D. Ravindranath, V. Kumar, J. Food Compos. Anal., 2005, 18, 583.
Caffeine content was determined from the HPLC analysis using caffeine standard. As can be observed in Table 2, the higher concentrations were obtained at 150 °C. Also, slightly larger caffeine contents were obtained with SP2 than with SP1 samples. Taking into account that the content of caffeine in green coffee beans is around 2-3 % weight, it can be estimated that the recovery of caffeine (caffeine in the extract / caffeine in coffee bean sample) was in the range of 50-90% at 150 °C. Table 2 – ASE of green coffee beans: caffeine content (% weight) in the extracts. SP1: entire beans; SP2: ground beans.

Source: http://www.iuct.net/oldweb/pdf/David%20Villanueva.pdf