Processing hexane–oil miscella using a nonporous polymeric composite membrane

Earlier studies on processing crude vegetable oils without added solvent using nonporous membranes showed excellent rejection of phospholipids and color compounds, while permeate flux needed improvement. In the present study, attempts were made to improve the permeate flux while maintaining the rejection performance of the membrane. Oil flux was increased by one order of magnitude by diluting with hexane that would offer greater productivity. The rejection of phospholipids in rice bran and soybean oils by the nonporous membrane was unaffected by dilution. The reduction of color compounds in rice bran oil was not severely affected indicating that Maillard browning products were rejected reasonably well even under dilute conditions. Rejection of carotenoids in soybean oil was sufficient for practical application up to 1:2 dilution. Nonporous membranes offer several advantages over ultrafiltration membranes for processing hexane–oil miscella, in terms of higher rejection of phospholipids, carotenoids and chlorophyll that could make the membrane process economically more attractive.