Molecular distillation of olive pomace oil ─ Multiobjective optimization for tocopherol and squalene

Olive pomace oil was distilled using a laboratory scale molecular distillation unit aiming a successful separation of squalene. Pressures were 0.02, 0.1 and 0.5 mbar, and temperatures ranged from 160 to 240 °C. Changes in total tocopherol and squalene concentrations of distilled olive pomace oils were monitored. Initial squalene concentration of 10613.1 mg kg−1 was succesfully reduced to 54.58 mg kg−1 at 0.02 mbar and 240 °C which corresponds to a reduction of 99.49% of initial. However, total tocopherol concentration also reduced to 20.2 mg kg−1 from an initial of 204.93 mg kg−1 at the same conditions. Similarly, an unfortunate loss of tocopherols with 90.14% at T = 240 °C and P = 0.02 mbar was observed. As being important antioxidants, tocopherols are desired to remain in oil; therefore, a multiobjective optimization (MOO) was performed to keep tocopherols in the oil at maximum, while minimizing squalene concentration. With an interactive MOO method, namely NIMBUS, 20 different alternative conditions could be generated. 9 of 20 paths could be considered as feasible and applicable for executing both objectives. One of the optimized conditions was 160 °C and 0.072 mbar where the highest tocopherol concentration of 204.721 mg kg−1 was obtained while squalene concentration was reduced to 3741.586 mg kg−1 in oil.