Water-free two-phase systems: phase equilibria and partitioning of vitamins from tomatoes (Solanum lycopersicum)

BACKGROUND: The present work provides diagrams for water-free two-phase systems based on polypropylene glycol 2000 (PPG 2000) + [C(2)mim][OAc] + alcohols (primary: methanol, ethanol, 1-propanol and 1-butanol; secondary: 2-propanol and 2-butanol; and tertiary: 2-methyl-2-propanol) at 298.15 +/- 1.00 K and 0.10 +/- 0.01 MPa. As a proof of concept, the systems were applied to study the selective partitioning of vitamins, namely beta-carotene and alpha-tocopherol.RESULTS: The hydrophilic/hydrophobic balance is the driving force for phase separation. The more hydrophilic alcohols are responsible for the wider biphasic area, and branching increases hydrophilicity and the biphasic area compared to linear alcohols. Additionally, it was verified that the mathematical determination of the tie-lines satisfactorily describes the positioning in the phase diagram when compared with the analytical determination. In the proposed systems, pure biomolecules partitioned selectively: alpha-tocopherol migrated to the PPG 2000 phase (top phase) while beta-carotene to the [C(2)mim][OAc] phase (bottom phase). For the study with real biomolecules, solid-liquid extraction was performed using 1-butanol (more selective alcohol) in a solid-liquid ratio of 1:10 at 200 rpm for 60 min. The partitioning trend followed the behavior of systems using pure biomolecules. The highest selectivity (5.3) was observed for the system composed of PPG 2000 + [C(2)mim][OAc] + 1-butanol or 2-butanol. The partition system did not impair the antioxidant potential expressed as DPPH inhibition.CONCLUSIONS: Water-free two-phase systems can be formed and applied to partitioning vitamins from tomatoes.(c) 2023 Society of Chemical Industry (SCI).