Membrane degumming and dewaxing of rice bran oil and its refining

A review on membrane technology application for vegetable oil purification processes

In current paper, a comprehensive review to contribute the present insight an implementations and the recent improvements through the diverse endeavor made by the researchers utilizing a membrane technique for degumming, deacidifying, dewaxing and discoloration edible vegetable oils with and without solvent availability and also the solvent recovery has been evaluated. Endeavors made with NF, UF, MF and non-porous membranes, have shown the capability of these membranes to predicate vegetable oil treatment. A membrane technique is noticeably simple and potentially provides many usefulness in vegetable oil purification. It appears that oils treatment with membranes, which carried out at low temperatures that provides saving energy, with real cancellation of stages, provides a promising alternate to conventional procedure, towards the accomplishment of eco-friendly and cost-effective operations that are technically sophisticated. Generally, the solvent (hexane-dilution) technique enhances the membrane oil flux. For dewaxing undiluted vegetable oils, the effective membrane was MF, whereas in dewaxing solvent-diluted oils process UF membranes were more energetic.

Membrane Technology in Degumming, Dewaxing, Deacidifying, and Decolorizing Edible Oils

A membrane process offers several advantages over the conventional method of oil refining. Conceptually, membranes could be used in almost all stages of processing. In the present review, various attempts made by the researchers towards degumming, dewaxing, deacidifying, and decolorizing edible oils using membrane technology with and without using solvents have been discussed. Attempts made with UF and nonporous membranes have demonstrated the ability of these membranes to separate phospholipids from undiluted and hexane-diluted oils and a high oil flux was obtained with UF membranes in hexane-diluted oils. MF membranes were very effective for dewaxing undiluted oils while UF membranes were effective in dewaxing hexane-diluted oils without a precooling step. Deacidification was successful only with either addition of an alkali followed by membrane filtration or by following an indirect route of selective solvent extraction of FFA followed by membrane separation. Consistent color reduction in terms of pigments (chlorophyll and xanthophylls) and other instrumental measurements (Lovibond and visible spectra) could be achieved only with nonporous membranes. Interestingly, these membranes did not have selectivity for alpha-and beta-carotenes. UF membranes are best suited for degumming and dewaxing applications, while nonporous membranes appear to be a better choice for achieving simultaneous degumming, dewaxing, and decolorization of oils. Hexane-dilution improved the oil flux of nonporous membranes by one order of magnitude, but further improvement is desirable for industrial adoption.