Mathematical modeling for simultaneous extraction and fractionation process of coffee beans with supercritical CO2 and water

Mathematical modeling of extraction and fractionation of caffeine from coffee beans using SCCO2 and water was developed. Simulation of the extraction and fractionation process was conducted using a model based on mass transfer balances to estimate recovery of caffeine as non-polar compound both in CO2 and water phases. The model was developed regarding extraction and fractionation systems including batch and counter-current configurations in our previous work. Even though polar compound of chlorogenic acid from coffee beans was extracted in water phase, the simulation was focused on the extraction and fractionation of caffeine because chlorogenic acid was not fractionated but only extracted by water. Effective diffusivity of caffeine in water phase was used as fitting parameter to compare the simulation and experimental results. The value of effective diffusivity used for simulation in batch system was 3 × 10−12, 7 × 10−12 and 1 × 10−11 m2/s; and the value used in counter-current system was 1 × 10−12 m2/s. The simulation results were compared with the previous experimental results [3] at various temperatures, pressures, CO2 flow rates, non-polar recovery section heights and ratios of coffee and water mass. The simulation could describe experimental results almost for all extraction conditions. The model just had lack agreement with the experimental result for the ratio of coffee and water mass in water phase.

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► Mathematical modeling based on mass transfer balance was successfully developed to describe extraction and fractionation of caffeine from coffee beans using supercritical CO2 and water.
► Predicted effective diffusivities of solute in water used for fitting parameter in the simulation of batch and counter-current semi-continuous process were 3 × 10−12 to 1 × 10−11 m2/s and 1 × 10−12 m2/s, respectively.
► The mathematical model could simulate concentration of fractionated caffeine both in supercritical CO2 and water phase satisfactorily.