Rejection of Carotenoids in Oil Systems by a Nonporous Polymeric Composite Membrane

Earlier studies by the authors on crude vegetable
oils showed that color compounds are reduced to the extent of
74–80% during membrane processing. In the present study, attempts
were made to understand the rejection mechanism of
carotenoids using real and model oil systems. In case of model
systems consisting of refined high-oleic sunflower (HOSF) oil,
lecithin and β-carotene, the rejection of carotenes was low (11–
20%). This could be explained based on the differences between
the model and real systems as well as on the solution-diffusion
mechanism controlling the material transport across the
membrane. This study revealed that β-carotene did not have
affinity for the phospholipid reverse micelles present in the oil.
Xanthophylls, the major carotenoids present in the crude soybean
oil, were rejected to the extent of 60% in the model system
(HOSF oil and lutein). High-performance liquid chromatographic
analysis of crude oil revealed that there were few other
xanthophylls, which are more polar than lutein. These unidentified
xanthophylls would be rejected to a much greater extent
by the hydrophobic membrane. The extent of color reduction
would depend on the actual composition of xanthophylls present
in the crude oil and their relative polarity.