Simultaneous degumming, dewaxing and decolorizing crude rice bran oil using nonporous membranes

Abstract

Efficacy of nonporous membrane has been evaluated for simultaneous degumming, decolorizing and dewaxing crude rice bran oil (CRBO). Membrane processing of CRBO showed that phospholipids (PL) were almost completely rejected (>99%) by nonporous membranes in both industrial and laboratory-prepared samples. Phosphorus levels in the membrane processed rice bran oil (RBO) samples were very low (<2 ppm) which indicated that both hydratable as well as nonhydratable PL were effectively rejected by the membrane. Further phosphoglycolipids were absent in the permeate (processed oil) whose presence in degummed RBO affects the color in the subsequent processing, posing problem in producing an acceptable quality final product. The color reduction measured in terms of area under the visible spectra (350–550 nm) was to the extent of 50–55%. The membrane process also reduced the wax content to the extent of 40–50%. Hexane-dilution improved the oil flux by one order of magnitude without affecting the selectivity to a greater extent. The results revealed that processing using nonporous membranes could be an effective pretreatment step for achieving the techno-economical benefits of physical refining of CRBO.