Experimental and modeling studies on extraction of catechin hydrate and epicatechin from indian green tea leaves

Abstract

A systematic investigation of effect of various parameters, for example, temperature, speed of agitation, particle size, and solid loading, on the percentage extraction of catechin hydrate (CH) and epicatechin (EP) was conducted. The extraction was performed with water, methanol, and ethanol. Water was found to be the best solvent for both. Percentage extraction of CH was found to decrease with temperature beyond 46°C; however, this is not the case for epicatechin. The thermal stability analysis of both the compounds was performed to ensure decomposition. This supported the experimental observation ofbatch extraction. Size ofparticle has little eect on percentage extraction ofEP, but it increases for CH with decrease in particle size, which is probably because of decrease in diffusion path length. Assuming flat geometry of the particles, the process is modelled and compared with experimental data at different experimental conditions. The experimental data fitted well with the model proposed by Wongkittipong. The effective diffusion coefficients through the solid matrix of Indian green tea leaves for CH and EP estimated from the diffusion model were found to be in the range 1.29×10-13 to 3.40×10-13 m2/s and 1.20×10-13 m2/s to 3.38×10-13 m2/s, respectively. The effect of temperature on diffusion coefficient of CH and EP was determined using the model. The energy of activation required for diffusion was found to be 32.78 and 30.28kJ/kmol, respectively for CH and EP. © 2010 Canadian Society for Chemical Engineering.