Phosphatidylcholine/vegetable oil pseudo-binary mixtures at the air–water interface: Predictive formulation of oil blends with selected surface behavior

The present work is an attempt to define how to formulate oil blends with an expected surface behavior using easily accessible data such as chemical compositions. Hence, we determined average surface properties of triglycerides (TG) from olive (O), soybean (S), and walnut (W) oils self-organized in Langmuir films alone or in pseudo-binary mixtures with phosphatidylcholines (PC).

Collapse pressure (π_c), compressibility modulus (K) and molecular area at the closest packing (A_min) were determined from π-mean molecular area (Mma) isotherms. The π_c-composition phase diagrams of TG–PC mixtures provided information about oils solubility limit with PCs in the monolayer phase. A thermodynamic equilibrium model was fitted to the line joining points of monolayer–TG_{liquid phase} coexistence and allowed to obtain interaction parameters, ω, which consistently with those of excess surface energy (ΔG_ex) and Mma deviations from ideality, contributed to describe interfacial intermolecular interactions. Oil molar fractions (x_TG) for TGs–PCs self-assembling into vesicles were estimated from x_TG values at π_c  30 mN/m (equilibrium π of bilayers), which resulted higher in egg PC (0.15, 0.2, 0.15 for O, S and W, respectively) than in dipalmitoyl-PC (0.125, 0.075, 0.1).

Principal component analysis performed on surface parameters, grouped S and W separated from O. This result was mainly influenced by variables estimating the effect of unsaturation degrees of fatty acids sterified at TGs, A_min and π_c.

Peanut oils surface data interpolated in π_c-C16/C18 and A_min–DBI correlation lines obtained with O–S mixtures (TG_mix) and with TG_mix–PC supported C16/C18 ratio and DBI as predictors to formulate oil blends with selected surface behavior.