Document Type : Research Article
Authors
1
Department of Food Science and Technology, Science and Research Branch, Islamic Azad University, Tehran, I.R. IRAN
2
Department of Chemistry, Faculty of Chemistry, Tehran North Branch, Islamic Azad University, Tehran, I.R. IRAN
3
Department of Food Technology, College of Abouraihan, University of Tehran, Tehran, I.R. IRAN
Abstract
Miscellas of canola were obtained by mixing its crude oil with hexane solvent at 80:20 and 70:30 ratios. Then, 16.1 M of phosphoric acid and 6.92 M of sodium hydroxide were mixed with the resulting micelles at 0.3% (w/w for degumming) and 13% (w/w for neutralizing), respectively, before two sequential Membrane Filtrations (MF). The MF unit had a crossflow mode equipped with three independent variables of transmembrane pressures or TMP (at 2, 3, and 4 bar), feed velocity (at 0.5 and 1 m/s), and temperatures (at 30, 40, and 50˚C) were used to determine the efficiencies of two MF processes and find out their optimum conditions. When the crude canola oil was mixed with 20-30% solvent and passed the two stages of MF (for degumming and refining) at TMP=2 bar, feed velocity=1 m/s, and temperature = 50˚C, the final polished canola oil had < 5% soap, < 5% phosphorus, < 5% fatty acids, and < 15% wax. Membrane refining, compared to chemical refining, significantly reduced the phosphorus content (50%), free fatty acids (29%), soap (99%), and wax (72%) of refined canola oil. While the permeate flux of canola miscella with 20% solvent increased with rising TMP, feed velocity, and temperature, the ones with 30% solvent did not increase with a similar trend. The highest permeate flux of refined canola oil reached 0.03 Kg/m2, s for miscella with 20% solvent when the feed velocity, TMP, and temperature of degumming or neutralization were 1m/s, 3-4bar, and 30-40oC, respectively. The dominant fouling changed from standard to cake blocking when the crude oil was mixed with 20 or 30% solvent, and the TMP of the MF process in each stage of degumming and neutralization was > 2 bar.
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