Effect of ethyl acetate, time and particle size on the kinetics of the oleoresin extraction process

Abstract

The kinetics of the extraction of oleoresin from ginger using ethyl acetate as the solvent was studied in this work. The effects of particle size and extraction time on oleoresin’s solvent extraction were analyzed to obtain optimization data. The temperature of the process was kept constant at 40 °C. The Ginger particle sizes ranged between 250–1200 μm at extraction times ranging between 10–70 min. Experimental data generated were fitted into an empirical model to determine the kinetic parameters. The oleoresin yield increases with increasing extraction time up to an optimum time, after which the yield remains constant and decreasing particle size. The results obtained for the kinetics studies reveal that with the introduction of the constant term accounting for the diffusion step separately (as an addition) into a single step first-order model (Patricelli’s first order model) raises from 87 % fitness of the model into becoming 99 % with the experimental data. And this improved form of Patricelli’s first-order model was found to have shown as good agreement with Patricelli’s 2-step kinetic model. These findings further confirm the oleoresin extraction process in the presence of ethyl acetate was found to be first-order kinetics involving two steps mechanism where the use of a single-step first-order model (Patricelli’s first-order kinetic model) and the choice of using ethyl acetate must have contributed to the strong resistance present in the first step of the extraction mechanism especially for the smaller particle size (250 μm). In getting the extraction yield improved, this study, therefore, recommends the use of small particle sizes (< 250 μm), higher temperatures (> 40 °C), and better alternative solvents like ethanol.