Processing vegetable oils using nonporous denser polymeric composite membranes

Membrane processing offers several advantages
over conventional processes for edible oil refining. In recent
years, processing solvent-extracted, screw-pressed, and used frying
oils using nonporous denser polymeric composite membranes
without pretreatment and addition of chemicals has been extensively
investigated. In the present review, results obtained with
real and model systems have been summarized and a comprehensive
explanation is provided on the mechanism of rejection
and differential permeation of oil constituents. Phospholipid-TG
and pigment-TG systems are construed as conventional
solute–solvent systems, and tocopherol-TG and FFA-TG systems
are treated as liquid mixtures exhibiting differential permeability.
Dense membrane theory appears more applicable than the reverse
osmosis theory in qualitatively explaining the differential
permeability of liquid constituents of the oil. Membrane processing
of oils appears to have the potential to be a one-step process,
especially for screw-pressed oils, in producing a premium-quality
product. However, the development of suitable membranes that
enable higher fluxes is necessary for industrial adoption of this
technology