A new approach for removal of caffeine from coffee using sunflower oil

Conventional decaffeination processes are capable of removing caffeine present in the coffee, but it also removes the flavouring/aromatic components to some extent and in many cases use toxic solvents. In this article a simple extraction method is presented using sunflower oil, a much less toxic solvent with good process and environmental benefits. Equilibrium experiments were carried out to examine the distribution ratio of caffeine, first in the solvent only (physical extraction) and then with a carrier-solvent organic phase (reactive extraction). The effects of caffeine concentration, carrier concentration, pH and type of solvent on the distribution coefficient were determined. It was observed that the distribution coefficient in sunflower oil increases with the increase of caffeine concentration and pH values. The value of the distribution coefficient was not affected greatly with the addition of Amberlite - LA2 (an amine carrier) in the solvent. The use of pure solvents like oleic acid has proven to be less effective compared to sunflower oil although equilibrium experiment showed otherwise. The process was applied to a small pilot-scale hollow-fibre membrane (HFM) contactor with the aim to apply this new and sustainable approach to remove caffeine molecules without affecting the natural flavour and aroma in the coffee. In the HFM approach using a single stage it was possible to extract 50-55% of caffeine with the addition of Amberlite - LA2 as a carrier, compared to 45-50% in physical extraction. Thus the proposed approach with sunflower oil (considered to be a "green" solvent) in hollow fibre membrane module can be recommended as an alternative process as it is environmentally benign, operator friendly and provide good process performance.