Optimization of molecular distillation to concentrate ethyl esters of eicosapentaenoic (20:5 ω-3) and docosahexaenoic acids (22:6 ω-3) using simplified phenomenological modeling.

Background: Squid oil contains high concentration of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The purpose of this work was to optimize the process of separation by molecular distillation of ω-3 fatty acid ethyl esters obtained from squid oil. The separation process was conducted in two stages in a laboratory-scale molecular distiller. A mathematical model based on the mass transfer phenomena was developed. The Nelder-Mead numerical method was used to optimize the model.

Results: The ω-3 content in the output material of the stage II increased with the temperature of stage I (T¹). The amount of distillated material in stage I increased and the distillated material in the stage II decreased with the increment of T¹. That implied a decreasing of the ω-3 recovery in the distillated material in the stage II. In addition, the ω-3 recovery increased with the temperature of stage II (T²), but the temperatures should be less than 140 °C to avoid chemical changes. The optimization results showed an optimal process at T¹ = 120.5 °C and T² = 140 °C.

Conclusion: The theoretical model and the optimization give decision criteria about the operative conditions for reaching the highest yield during molecular distillation of ω-3 fatty acid ethyl esters.